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Evaluating the potential of plant growth promoting cyanobacteria as inoculants for wheat
Abstract
Diazotrophic heterocystous cyanobacteria are known to possess the ability to form associations with vascular/non-vascular plants and produce growth-promoting substances. Most of the work on cyanobacterial inoculants has been focused on rice and other crops have received little attention. Our investigation was directed towards evaluating the potential of three cyanobacterial isolates from the rhizosphere of wheat, with emphasis on their plant growth promoting activity in pot culture experiments. All treatments were taken up in sterile soil, under controlled conditions of National Phytotron Facility, IARI and in the Glasshouse, using unsterile soil. The treatments in which all the three-cyanobacterial isolates were applied along with 1/3 N + P + K gave statistically equivalent results as compared to application of with full dose of chemical fertilizers in terms of grain yields. Significant enhancement in microbial biomass carbon in the treatments was observed at mid-crop and harvest stage, over uninoculated controls. Field level evaluation of these strains and testing under different agro-climatic conditions will help to further evaluate their agronomic efficiency and utility in integrated nutrient management of wheat crop.
... h -1 atmospheric nitrogen (7). Despite being suited for fully independent existence, cyanobacteria possess a unique ability to form associations with some plant species and promote their growth and productivity in variety of agricultural and ecological situations (10). In recent years, the use of cyanobacteria in agriculture has received increased attention, due to their ability to produce various biologically active compounds and biostimulants including phytohormones (auxins, gibberellins and cytokinins), amino acids and vitamins (vitamin B group) (11)(12). ...
... Furthermore, it has been well-documented that the production of phytohormones and other growthstimulating substances such as proteins, vitamins, carbohydrates, and amino acids by cyanobacteria are among the most important factors influencing plant growth (33). In addition, cyanobacteria enhance plant growth through the improvement of soil structure by secretion of mucilage compounds and exopolysaccharides (EPS) (10). The EPS increases soil water holding capacity through the aggregation of soil particles and accumulation of organic matter in the soil (34). ...
... The biosynthesis of peppermint EOs takes place in highly specialized epidermal oil glands. The biosynthesis process of EOs begins with the ionization and cyclization of geranyl diphosphate (C 10 (26). In the present study, the expression of LS gene significantly increased in response to both cyanobacteria inoculation. ...
Background: Mentha piperita L. is one of the most important aromatic crops and is cultivated worldwide for essential oils (EOs).
Objectives: The aim of the present study was to investigate the potential of two cyanobacteria, Anabaena vaginicola ISB42
and Nostoc spongiaeforme var. tenue ISB65, as biological-elicitors to improve the growth and essential oil production of
M. piperita.
Materials and Methods: In this experiment, inoculation of M. piperita with cyanobacteria was performed by adding
1% cyanobacterial suspension to the soil of treated pots on the first time of planting and every 20 days thereafter. The
experiment was performed in a randomized complete block design in an experimental greenhouse condition. After 90 days
planting, the vegetative growth factors, the content of photosynthetic pigments, as well as the quantity and quality of EOs
of treated and control plants were evaluated. Also, quantitative changes in the expression of some menthol biosynthesis-
related genes were investigated.
Results: Cyanobacterial application led to significant increases in M. piperita growth indices including root and shoot
biomass, leaf number, leaf area, node number and ramification, as well as photosynthetic pigments content. The statistical
analysis showed a 41-75 % increase in some of these growth indices, especially in Nostoc-treated plants. A. vaginicola and
N. spongiaeforme var. tenue inoculation led to a 13% and 25% increase in the EOs content of M. piperita, respectively.
The EOs components were also affected by cyanobacterial treatments. According to the statistical analysis, Nostoc-treated
plants showed the highest amount of (-)-menthone and (-)-limonene, with a 2.36 and 1.87-fold increase compared to the
control. A. vaginicola and N. spongiaeforme var. tenue inoculation also led to 40% and 98% increase in transcript level of
(-)-limonene synthase gene, respectively. The expression of the (-)-menthone reductase gene, was also increased by 65%
and 55% in response to A. vaginicola and N. spongiaeforme var. tenue application, respectively.
Conclusions: Our data demonstrated that in addition to growth enhancement, these two heterocystous cyanobacteria
improved the quantity and quality of EOs by up-regulating the key genes involved in the menthol biosynthetic pathway.
Based on our results, these cyanobacteria can be considered valuable candidates in the formulation of low-cost and
environmentally friendly biofertilizers in sustainable peppermint production.
... Bu nedenle çalışmamızda her iki mikroalg ayrı ayrı izole edilmiş ve çalışmamızda eşit oranda karıştırılarak kullanılmıştır. Denemede kullanılan iki mikroalgin karışık kültürlerinin tek tek uygulanmasından daha etkili olduğu ise yapılan literatür taramalarında da rapor edilmiştir (Karthikeyan et al., 2007;Pereira et al., 2009;Osman et al., 2010;Renuka et al., 2017). Saksı denemesinde kullanılan toprakların pH'ı 7.71 olarak belirlenmiştir. ...
... %2'lik uygulama dozunun uygulanması aşırı kimyasal gübre kullanımını önleyerek bitki boyunda artışa da neden olmaktadır. Elde ettiğimiz sonuçlarımızı; buğdayda (Mohiuddin et al., 2000;Karthikeyan et al., 2007), Lupinus termis (Haroun & Hussein, 2003), bezelye (Osman et al., 2010), çeltikte (Saadatnia & Riahi, 2009;Begum et al., 2011), arpa, fiğ ve nohutta (Sezen & Küçük 2021) mikroalg aşılamaları sonucu elde edilen bulgular da desteklemektedir. ...
... Mercimek ve mısırda kök ve bitki boyundaki artışın mikroalglerin sitokinler (Hussain et al., 2013), oksinler (Prasanna et al., 2010) gibi bitki gelişimini arttıran substratların bir veya daha fazlasının aktivitesinden kaynaklandığı düşünülmektedir. Siyanobakterilerin fitostimülatör potansiyellerinin, birliktelik kurdukları bitkilerde atmosferik azot fiksasyonunu kullanılabilir hale getirdiği yapılan çalışmada bildirilmiştir (Karthikeyan et al., 2007). Kök uzunluğu ve buna bağlı olarak yüzey alanındaki artış, topraktan su ve besin alımının stimülasyonu tarafından bitkinin gelişimini de desteklemektedir (Dineshkumar et al., 2019). ...
Bu çalışmada Mısır (Zea mays L.) ve mercimek (Lens culinaris Medik) gelişimi üzerine etkilerini belirlemek amacıyla, Bazı Şanlıurfa baraj göllerinde yoğun olarak bulunan Microcystis viridis ve Aphanizomenon gracile ’in karışık kültürünün farklı dozlarının etkisi araştırılmıştır. Siyanobakteri karışımından hazırlanan dozlar, topraklara püskürtülerek uygulanmıştır. Kök uzunluğu bakımından mercimekte % 2’lik doz ve mısırda % 1 uygulama dozu sırasıyla %92 ve %60 daha etkili bulunmuştur. Siyanobakteri karışımının % 2’lik uygulama dozu bitki boyu artışında kontrole göre % 70 ve %42 daha etkili görülmüştür. Yeşil aksam ağırlıkları bakımından, % 2’lik doz uygulanan mısır ve mercimek, kontrole göre %164 ve %30 daha etkili bulunmuştur. Kök kuru ağırlığında ise % 2’lik uygulama dozu her iki bitkinin kontrole göre % 680 ve % 139 daha etkili okluğu tespit edilmiştir.
... The entire setup was kept in a growth chamber, maintained at 27 ± 2 °C and illumination of 50 µmol photons m -2 s -1 in a 12 h light-dark cycle (Nilsson et al. 2002). After 10 days incubation, morphometric parameters including root length, shoot length, total seedling length, leaf length, lateral root numbers, fresh and dry weight and responses of the seedlings were determined (Karthikeyan et al. 2007). ...
... The set ups were incubated as mentioned in section "Preparation of cyanobacterial extracellular product (CEP) and biomass wet extract (BWE)". After 10 days of incubation, morphometric parameters including root length, shoot length, leaf length, lateral root numbers and fresh weight of seedlings were determined (Karthikeyan et al. 2007). The web tool ClustV and CIMminer is used to generate the heat map for both length and weight of the seedlings respectively. ...
Cyanobacteria are essential in paddy fields, aiding soil fertility. Soil pollution, caused by excessive chemical fertilizers and pesticides, poses a global crisis. To use cyanobacterial biofertilizers effectively, strains need to tolerate and break down these agrochemicals, including herbicides. This study examined the ability of potential plant growth promoting cyanobacterial strains Nostoc commune MBDU 101 and Scytonema bohneri MBDU 104 to tolerate salinity - NaCl (100 mM) and chlorpyrifos (5 mg L⁻¹) stress of Oryza sativa L. grown under hydroponic conditions, both individually and in combination with each other. These cyanobacterial strains have already been proven for their ability to produce phytohormones and are now assessed for their salinity and insecticide tolerance through growth parameters, including chlorophyll, carotenoids, and protein content, over 24 days under test conditions. Those treatments that demonstrated optimal cyanobacterial growth were subsequently tested for their impact on O. sativa L. under hydroponic conditions along with a control group. Notably, N. commune MBU101 under chlorpyrifos stress showed distinctive positive effects on plant growth, with a shoot length of 3.18 cm, seedling length of 6.68 cm, 13 lateral roots, and a leaf length of 6.73 cm. Scytonema bohneri MBDU 104 (SB104) exposed to NaCl stress exhibited the highest seedling weight among all treatments and the control. GC-MS analysis of N. commune revealed the presence of 3,5,6-trichloro-2-methoxypyridine (TMP) and 3,5,6-trichloro-2-pyridinol (TCP) as degradation products of chlorpyrifos. These findings emphasize the potential of these cyanobacterial strains in enhancing soil health and crop growth while mitigating the environmental impact of agrochemicals.
... Earlier reports on cyanobacteria exhibited the decisive aspect of accumulating the soil N content and other essential nutrients, which are known to have a wide range of effects on plant growth and ion uptake [21,22]. Besides, cyanobacteria are natural creators of phytohormone synthesis, including IAA and IBA [22,23]. ...
... It involves physiological aspects like germination, stem elongation, division, and delaying the senescence in plants [41]. Various cyanobacteria species were reported for indolic compound production [21,75]. Among these, auxin is involved in early flowering, root length, fresh weight, pigments, and sugars in plants [61]. ...
Cyanobacteria stand out as prospective candidate among various biostimulant microbes due to their ability to produce phytohormone-related substances that stimulate plant growth. In this research line, the bio-stimulatory potential of Nostoc sp. MJU 001 and Scytonemabohneri MBDU 104 on Trigonella foenum-graecum L. seeds was explored. The plant growth-promoting traits of cyanobacteria were evaluated through pot experiments and morphometric growth analysis. Pot experiments were conducted using a 1% biomass extract and the cell suspension of Nostoc sp. MJU 001 and Scytonemabohneri MBDU 104. After 20 days, the growth development profile of Trigonella foenum-graecum L. was assessed through morphometric growth factors. In addition, the quantitative analysis of biochemical characters, including chlorophyll content, total proteins, total soluble phenol, flavonoids, α-amylase activity, and polyphenol activity, was estimated. Moreover, these parameters play a crucial part in the overall health and vitality of the plant. Based on the growth stimulatory potential, the crude extract of the Nostoc sp. MJU 001 was purified by preparative–HPLC and explored through UPLC-MS to identify possible plant growth promoters. The enterprising approach of cyanobacteria biostimulants holds tremendous promise in future agricultural practices. Through their ability to produce phytohormones-related substances, cyanobacteria can stimulate the growth and development of plants, as evidenced by their biostimulatory response to fenugreek. By utilizing cyanobacteria strains like Nostoc sp. MJU 001 and Scytonemabohneri MBDU 104, we can achieve sustainable agriculture while reducing our reliance on synthetic inputs. This research opens avenues for further exploration and implementation of nature-friendly plant nutrition and cultivation solutions.
Graphical abstract
Cyanobacteria bio-stimulant model for crop improvement and productivity on Trigonella foenum-graecum L.
... Bón phân vi sinh hoặc chế phẩm sinh học chứa tảo lam được nhìn nhận là biện pháp kỹ thuật nâng cao sinh khối vi sinh vật trong đất trồng trọt như: sinh khối tảo lam trong đất canh tác lúa mì [35], [36] và đất canh tác đậu xanh [37]; hỗn hợp tảo lam với các vi sinh vật có ích khác trong đất trồng bông [38], đất trồng đậu bắp [39] và đất trồng hoa cúc [40]. Hỗn hợp tảo lục và tảo lam dạng khô cũng có hiệu quả trong tăng sinh khối vi sinh trong đất trồng lúa mì [41]. ...
... Bột tảo lam khô được coi là một loại phân bón hữu cơ (tan chậm) [42], [43] chứa một số chất kích thích sinh trưởng đối với cây trồng [44]. Do đó, việc sử dụng tảo lam rất có hiệu quả trong cải thiện sự sinh trưởng, phát triển, năng suất và chất lượng cây trồng như ngô, lúa mì và lúa gạo [35], [45]- [47], đậu và củ cải đường [48] và một số loại rau [49]. ...
Đất nông nghiệp ở nước ta không những đang suy giảm về diện tích mà còn đối mặt với tình trạng suy thoái về chất lượng do nhiều nguyên nhân thuộc cả về điều kiện tự nhiên và kinh tế - xã hội. Các vật liệu cải tạo đất truyền thống, điển hình là phân hữu cơ, đang ngày càng cạn kiệt về số lượng và khó kiểm soát về chất lượng. Gần đây, vai trò và tiềm năng ứng dụng của các loại vi tảo nói chung và tảo lam nói riêng trong nông nghiệp nhận được nhiều quan tâm của các nhà nghiên cứu. Mục tiêu của bài tổng quan là khái quát những lợi ích mang lại khi sử dụng tảo lam trong nâng cao độ phì đất cũng như cải thiện năng suất và chất lượng nông sản. Tác giả đã tiếp cận và cập nhật các kết quả nghiên cứu mới về ứng dụng của tảo lam trên thế giới và các nghiên cứu về sự phân bố, thành phần loài và điều kiện nuôi trồng ở Việt Nam. Theo đó, hiệu quả của sử dụng tảo lam trong cải tạo đất đã được chỉ ra một cách có hệ thống và điều kiện của Việt Nam hoàn toàn phù hợp cho việc nuôi trồng loại vi sinh này. Các nghiên cứu sâu hơn cần được thực hiện để khắc phục những trở ngại trong sử dụng và nuôi trồng vi tảo ở nước ta.
... Zinc application positively affected nitrogen content Shivay et al. (2015), and higher Zn application was found to be more effective for Zn accumulation in grains (Gomez-Coronado et al. 2017). Microbial inoculation as seed treatment or seedling dip has been shown to increase wheat yield and nutrient uptake (Karthikeyan et al. 2007;Prasanna et al. 2012;Rana et al. 2012). In the present study, inoculation of aqueous suspension was used as a foliar spray, which demonstrated a better influence on both soil and crop growth parameters. ...
Nano-fertilizers possess a substantial promise in modern agriculture for nutrient utilization efficiency and minimizing environmental impact. However, limited information exists regarding the relative performance of nano-urea, and urea with nano-zinc or other zinc (Zn) fertilization strategies. A two-year (winter seasons of 2021-22 and 2022-23) field experiment was carried out through a split-plot design to evaluate the efficacy of combined effects of nitrogen (N) sources: urea ± nano-urea, microbial inoculation and Zn fertilization, particularly, nano-urea and zinc in terms of growth, yield, nitrogen uptake, and use efficiencies of wheat. In 2021-22 and 2022-23, the application of N 130 kg ha −1 increased wheat grain yield by 23.2% and 33.1%, respectively compared to the control plot. In contrast, employing 97.5 kg ha −1 and 65 kg ha −1 of N along with two foliar sprays of nano-urea at the rate of 2.5 l ha −1 reduced yields by 3.4-7.8%, 6.8-12.4% in both years of the study in comparison to N 130 kg ha −1. Foliar spray of 0.1% nano-ZnO at maximum tillering, anthesis, and grain filling stages enhanced yield by 3.7-4.5% when compared to no Zn. Among N sources, the application of N 130 kg ha −1 has resulted in improved yields, N content and uptake. Within Zn fertilization, the application of 0.1% nano-ZnO foliar spray resulted in increased wheat yields and nitrogen uptake. In conclusion, it is recommended to apply 130 kg N ha −1 in three splits along with 0.1% foliar sprays of nano-Zn oxide during the maximum tillering, anthesis, and grain filling stages for enhancing grain and straw yields, as well as improving nitrogen content, uptake and its efficiency.
... The application of cyanobacteria as a biofertilizer in row crops, such as rice, wheat, soybean, cotton, and maize, has been well documented [6,7]. However, most of these studies have been conducted either directly in the field (such as a paddy rice field) or used cyanobacteria inoculants for their experiments. ...
Cyanobacteria, an important addition to biofertilizers, are gaining popularity for their multifaceted benefits in sustainable agriculture and ecosystem restoration. However, harmful algal blooms (HABs) in freshwater, predominantly caused by cyanobacteria, prevent sunlight penetration into the water and develop hypoxic and anoxic conditions. We collected cyanobacteria slurry from Lake Jesup (Central Florida, USA), repurposed it as a biofertilizer, and incorporated it in a typical South Florida calcite soil for high-value okra (Abelmoschus esculentus; var: Clemson spineless) production. Experiments were conducted at the Organic Garden Shade House and Greenhouse located inside the main campus of the Florida International University (FIU), FL, USA. A two-year experiment with four different treatments was conducted, namely, (a) control (C; no fertilizer applied), (b) total synthetic (TS), (c) total biofertilizer (TB; only cyanobacteria biofertilizer was applied), and (d) half and half (HH; 50% biofertilizer + 50% synthetic fertilizer), which were arranged in a randomized complete block design (RCBD) with six replications for each treatment. Our results indicate that TB and TS produced about 29 to 33% higher SPAD (soil plant analytical development) readings than the control. The absence of interveinal chlorosis (yellowing of leaves) in the TB and HH treatments suggests that the cyanobacteria-based biofertilizer had a role in supplying one of the critical micronutrients, iron (Fe). Analysis of the biofertilizer indicated 2000 ppm Fe content, which directly supports our observation. Similarly, average plant height (61 cm), yield (130 gm per pot), and crop biomass (67 gm) productions were significantly higher in TB than in the control. Overall, this study documents the potential of cyanobacteria biofertilizers as a viable option compared to synthetic fertilizers for sustainable crop production and soil health improvement.
... Moreover, Jagannath et al. (2002) in his study BGA was found to enhance all the morphological characters and biomass of the chickpea. The growth promoting activity of Cyanobacteria as inoculants of wheat was also observe by Nanjappan et al. (2007) and Basavaraja (2019). The data on seedling viogur as influenced by different BGA concentrations in various crops are presented in Table 2&3. ...
An experiment was conducted to know the influence of different concentrations of Spirulina platensis extract on seed germination and seedling vigor of various crops. The experiment involved eight different crops, and five concentrations of the algal extract were applied. The parameters evaluated included seed germination percentage, seedling vigor index-I and II. The results indicated significant variations in seed germination and seedling vigor among different crops and concentrations of Spirulina platensis extract. Among different concentrations of Spirulina platensissignificantly higher (85.75 %) seed germination was recorded in BGA @100 % concentration in all the crops selected for study. This study provides valuable insights into the potential use of algal extracts for enhancing crop growth and productivity.
... This nitrogen fixing bacteria have been demonstrated to improve wheat production, dry weight, and growth of root and branches (Chittora et al., 2020). Crop traits such as plant height, dry weight, grain number, and bio-carbon content are all improved in wheat crops that have had cyanobacterial inoculation (Karthikeyan et al., 2007). Its inoculation can enhance the germination and growth characteristics of rice seeds (Jhala et al., 2017). ...
In the ever-evolving landscape of sustainable agriculture, cyanobacterium has emerged as a viable option to offer
multifaceted benefits to both crops and the environment. This comprehensive review navigates the contributions
of cyanobacteria in agriculture and begins with an insightful exploration of their fundamental role in sustainable
agricultural systems. This review article explains the mechanisms through which cyanobacterium may foster plant growth and demonstrates their ability to boost crop yields and optimize nutrient utilization. Their capacity to alleviate stresses in plants in drought to salinity conditions, unveils a remarkable feature. Beyond the fields, this bacterium plays a crucial role in protecting our environmental as well as help through phytoremediation by
addressing soil pollution and effectively removing heavy metals and organic contaminants. In the context of sustainable agriculture, it represents an environmentally friendly alternative to chemical fertilizers and can be seamlessly integrated into organic farming. Looking forward, this review peers into the future of its applications in agriculture, pragmatically addressing the hurdles of commercialization, regulatory compliance, and public
perception. In conclusion, this review consolidates the pivotal contributions of this bacterium to sustainable agriculture, underscoring the imperative of ongoing research and innovation in harnessing their transformative potential for a greener and more productive agricultural practices in future.
... The Linear Discriminant Analysis Effect Size (LEfSe) method confirmed these findings (Fig. 2D). Various taxa affiliated with these phyla are known for their prominent roles in (a) nutrient cycling and mobilization (Liu et al., 2016;Begmatov et al., 2021); (b) carbon sequestration (Muñoz-Rojas et al., 2018); (c) soil stability and fertility (Chamizo et al., 2018;Gonçalves, 2021); (d) suppression of abiotic and biotic stressors (Poveda, 2021;Zhang et al., 2021a); (e) and release of plant growth-promoting substances (Karthikeyan et al., 2007;Gonçalves, 2021). Therefore, MCs may disrupt and alter the plantmicrobiota homeostasis in agroecosystems in a way that affects soil quality and crop performance. ...
... Ever increasing prices of Nitrogen fertilizers and risk of environmental pollution and groundwater corruption, warn for their careful and well-organized use. Many cyanobacteria species have been previously tested for their ability to be used as biofertilizer (Karthikeyan et al., 2007). Field trials of cyanobacteria as biofertilizer are being carried out for a long time for different crops (Vaishampayan et al., 2001;Abd-Alla et al., 1994). ...
Wheat is rich in carbohydrates, Protein and essential Vitamins and Minerals such Vitamins B and E, Calcium and Iron, as well as fibre. Wheat is an important cereal crop in achieving global Food security. It is cultivated worldwide and is second highest in production. Wheat production is affected mainly by biotic and abiotic stresses all over the world. Maximum yield of wheat can be attained over balanced consumption of all plant nutrient resources. In recent past due to increased cost of chemical fertilizer and with moto of tumbling environmental pollution, creation of amplified awareness on the use of organic sources with bio-fertilizers which are the sources of macro, micro and secondary nutrients to endure both the soil fertility and productivity. The combined nutrient supply contemplates to collective use of inorganic and organic sources of plant nutrient and bio-fertilizers for crop productivity apart from keeping up inspiring soil health. Since past few years, bio-fertilizers like Azotobacter, PSB, (Phosphate solubilizing bacteria). Azospirillum and liquid bio-fertilizers have shown fabulous potential to improve yield of wheat as these are eco-friendly and low-cost agriculture inputs. Managing Nitrogen inputs in wheat production systems is a significant issue in order to attain maximum profitable production, and minimum negative environmental influence. Wheat production can be enhanced to two to three fold by implementing the cyanobacteria based bio fertilizer. Current study indicates a boost in crop growth, height, thickness of stem, increase in number of grain pods and quantity.
... L'inoculazione di microalghe nelle colture promuove le piante per generare enzimi di difesa, trasportatori e agenti chelanti tra le altre sostanze che aumentano la crescita, la resa delle colture e l'immunità delle piante ai patogeni (Gupta et al., 2013). Inoltre, aumenta la qualità dei frutti, le caratteristiche nutrizionali, la resa dei cereali (Coppens et al., 2015) e migliora le interazioni microbiche degli organismi presenti nel suolo (Karthikeyan et al., 2007). I diversi tipi di alghe più studiati per le loro applicazioni come biofertilizzanti in varie colture sono dettagliati nella Tabella 1. Sebbene inizialmente l'applicazione di alghe marine vive essiccate fosse la più comune, oggi la ricerca ha aperto una nuova possibilità di ricerca nelle alghe d'acqua dolce (Nain et al., 2010). ...
Riassunto I biofertilizzanti a base di estratti di microalghe rappresentano un'alternativa ecologicamente sostenibile per potenziare la produzione agricola e proteggere le colture. Questo campo è uno dei più promettenti ambiti della biotecnologia e della bioingegneria, ricco di potenzialità da scoprire. Le microalghe sono organismi microscopici multifunzionali, capaci di effettuare la fotosintesi e di fornire alle piante azoto in forme prontamente assimilabili, oltre a migliorarne lo sviluppo tramite l'azione di fitormoni come auxine, gibberelline e citochine, nonché fornendo loro macro e micronutrienti essenziali. Per crescere, questi organismi fotosintetici hanno bisogno di condizioni simili a quelle delle piante: luce, temperatura (compresa tra i 18 e i 28 gradi Celsius), pH (tra 6 e 9) e nutrienti provenienti da fonti organiche come compost, letame di vario genere, oppure inorganiche come agrochimici. Possono essere coltivati sia su larga scala all'aperto, in sistemi ad atmosfera aperta, che in condizioni controllate, all'interno di fotobioreattori. Nella nostra sintesi, mettiamo a confronto i vari tipi di biofertilizzanti, le diverse colture di microalghe e la loro produzione su vasta scala, offrendo una panoramica sulla situazione mondiale di questi prodotti e analizzando le principali sfide da affrontare, come il costo di produzione, la selezione e l'ottimizzazione delle tecniche di isolamento dei ceppi e la progettazione dei bioreattori. INTRODUZIONE: Uno dei problemi più significativi che il mondo affronta nell'ambito agricolo è dato dall'abuso indiscriminato di prodotti chimici agricoli o fertilizzanti artificiali. Questi prodotti, non solo non hanno portato ad un aumento delle rese nella produzione delle colture ma hanno invece causato diversi effetti negativi sull'ambiente e sulla salute umana. Tra i problemi ambientali causati si annoverano il degrado ecologico che ha creato zone marine morte, l'eutrofizzazione, l'infertilità del suolo e la perdita di biodiversità (Kohler e Triebskorn, 2013). Da un punto di vista della salute umana, è stato dimostrato che l'utilizzo di tali prodotti nel tempo colpisce sia gli agricoltori che li applicano sia le persone che vivono nelle vicinanze delle aree di applicazione (Vargas, 2015). Inoltre, i prezzi dei fertilizzanti azotati hanno avuto un aumento sul mercato, portando ad un incremento dei costi di produzione e una diminuzione della redditività delle colture. Un'alternativa per ridurre l'uso di sostanze chimiche è l'uso totale o parziale di biofertilizzanti (Aghiliet al., 2014), definiti come prodotti contenenti microrganismi vivi o componenti derivati da organismi come batteri, funghi e alghe che promuovono le proprietà chimiche e biologiche del suolo, oltre a ripristinare la sua fertilità e stimolare la crescita delle piante (Abdel-Raouf et al., 2012). Inoltre, forniscono un passo importante nell'agricoltura sostenibile (Lauriano-Barajas e Vega-Frutis, 2018), essendo rispettosi dell'ambiente e accettati dalla società (Mamani de Marchese Filippone, 2018).
... also improved the quality of flowers (Rosa spp.) (Tripathi et al., 2008). Some other study looked into how rice (Oryza sativa L.) growth was impacted by Aulosira fertilissima (Karthikeyan et al., 2007). The authors claimed that auxins, cytokinins, and gibberellic acid-rootpromoting hormones-increased the growth of rice seedlings. ...
Microalgae are microscopic organisms that have a broad range of applications, from wastewater treatment, CO2 mitigation to therapeutic proteins, and pharmaceuticals. Recently, the combination of wastewater treatment-based microalgae and the use of the obtained biomass as biofertilizers/stimulants/pesticides have been highly emphasized for their use in the agriculture field. Biofertilizers are a need of today’s agriculture practices due to the increasing demand for food to feed a hungry planet while avoiding chemical contamination by the over-application of synthetic fertilizers. There is a constant need for modern techniques for the use of microalgae in a sustainable manner to harness their products to their full extent. Various types of bioreactors are available on the market, each with its own advantages and disadvantages, which, based on their efficiency, can be used for microalgae cultivation. This review aims at reporting recent developments in microalgae biotechnology, especially related to CO2 mitigation, wastewater purification, biofuel, feedstock, future food, therapeutic proteins, pharmaceuticals, and biofertilizers, highlighting some of the current research in this field and future development priorities.
... Certain cyanobacteria (free-living blue-green algae) can efficiently transform atmospheric nitrogen (N 2 ) into organic nitrogen forms, which is one of the vital nutrients for plant growth (Dey et al. 2017;Gonçalves 2021;Renuka et al. 2018). Cyanobacteria has specialized cells known as heterocysts, that can fix atmospheric nitrogen and, as a result, are able to meet the needs of soil macro and micro fauna as well as flora and plants (Babu et al. 2015;Karthikeyan et al. Brevundimonas sp. ...
Abstract
Agriculture is undergoing a paradigm shift as it moves away from relying only on agrochemicals toward natural-based
product to enhance plant growth and productivity while sustainably maintaining soil quality and productivity. In this
sense, microalgae and bacteria offer a unique potential due to the growing use of novel and eco-friendly products such as
biofertilizers, biostimulants, and biopesticides. Microalgae improve crop growth and health by fixing nitrogen, releasing
soil trace elements, solubilizing potassium, and phosphorus, producing exopolysaccharides, and converting organic matter into utilizable nutrients. They also release bioactive substances including, carbohydrates, proteins, enzymes, vitamins,
and hormones, to promote plant growth, control pests, and mitigate plant stress responses. Even though it has long been
known that microalgae produce various bioactive and signaling molecules (like phytohormones, polysaccharides, lipids,
carotenoids, phycobilins, and amino acids) which are effective in crop production, the targeted applications of these
molecules in plant science are still in the very early stages of development. Microalgae are beneficial to bacteria because
they produce oxygen and extracellular chemicals, and bacteria, in turn, provide microalgae with carbon dioxide, vitamins,
and other nutrients in exchange. This review discusses the possible role of microalgae in increasing crop yield, protecting
crops, and maintaining soil fertility and stability, and it points out that interactions of microalgae and bacteria may have
a better enhancement of crop production in a sustainable way than using either of them alone.
... In particular, nitrogen fixation by cyanobacteria has been widely used. Karthikeyan et al. (2007) reported that Calothrix ghosei promoted wheat growth by producing somatotropin and fixing atmospheric nitrogen. Microalgae have also received more attention for their role in the remediation of saline-alkali soil. ...
Soil salinization is a serious ecological problem. Bacteria and cyanobacteria both have great potential for saline-alkali soil improvement. However, the effect of co-applying bacteria and cyanobacteria on soil improvement and crop growth promotion in saline-alkali soil remains unclear. In this study, the effects of Paenibacillus sabinae (potassium-solubilizing bacteria) and Leptolyngbya sp. RBD05 (cyanobacteria), produced in brewery wastewater, on soil properties, wheat growth, and wheat stress tolerance were studied by applying them to saline-alkali soil alone or in combination. The study indicated that P. sabinae and Leptolyngbya sp. RBD05 have important roles in increasing wheat growth, N:P ratio, K:Na ratio, proline content, and superoxide dismutase activity, as well as in slowing the decline of soil nutrient content caused by wheat absorption. Compared to the control group, the co-application had the best effect on soil available K content, wheat dry weight, and wheat root length (increased by 26%, 85%, and 70%, respectively); and it was more conducive to promoting the wheat K:Na ratio (increased by 41%), which would better improve the wheat’s saline-alkali stress tolerance. This study provided a new and clean strategy to improve saline-alkali soil quality and promote crop growth by the bacteria and cyanobacteria produced from wastewater treatment.
... In this study, development in wheat growth and yield under the increasing nitrogen rates were reported by Stirk et al. (2002). The same effect of cyanobacteria this result is like those reported by Karthikeyan et al. (2007) and El-Zemrany (2017), who reported the effects of inoculant with cyanobacterial strains on wheat showed differences in terms of the appearance of plants. This was in plant height, dry weight, and grain yield of wheat crop. ...
... Cyanobacteria are an important group of gram-negative photo autotrophic bacteria (significant nitrogen-fixing bacteria) in various agricultural soils (Vargas & Novelo, 2007). Additionally, have an ever-evolving photosynthetic mechanism that produces oxygen (Prabina et al., 2004), develop growth-promoting compounds that significantly increase pigment content, and increase the activities of nitrate reductase, and photosynthetic efficiency (Nanjappan-Karthikeyan et al., 2007). Cyanobacteria can assimilate N 2 and transform into an accessible type of ammonia (vitamins and hormones) needed for plant growth (Priyadarshani & Rath, 2012). ...
... Cyanobacteria have the ability to increase root and stem growth, dry weight, and yield in wheat [ 8 , 20 ]. The cyanobacteria used in wheat cultivation showed effective results on the appearance of plants in terms of increasing plant height, dry weight, and a number of grains of the wheat crop, in addition to some important positive changes in increasing the bio-carbon content of the beneficial microbial mass [ 22 ]. The effects of cyanobacteria on rice crop growth have demonstrated that cyanobacterial inoculation can improve rice seed germination and growth parameters [ 23 ]. ...
Cyanobacteria are bioactive photosynthetic prokaryotes that have a superior ability to fix atmospheric nitrogen and are highly competitive in the microflora community. They also improve the physical and chemical properties of the soil and increase its water-holding capacity. Therefore, cyanobacteria are used as biofertilizers in agriculture. Cyanobacteria are able to promote plant growth by providing nutrients and producing many highly effective chemical compounds, such as enzymes and hormones, in the plant rhizosphere, giving the plant a highly competitive ability. In addition to activating plant defense responses against soil-borne pathogens, they have an effective strategy as a biocide against bacteria, fungi, and nematodes that attack plants. With multiple beneficial biological roles, the environmentally friendly cyano-bacteria occupied the role of the maestro in sustainable agriculture.
... Song et al. [47] demonstrated that biofertilizers of nitrogen-fixing cyanobacteria (NFC) have a great potential in improving fertility of the soil and increment yield of rice paddy. Furthermore, Karthikeyan et al., [48] mentioned to promising cyanobacterial strains; Calothrix ghosei, Hapalosiphon intricatus and Nostoc sp. Which enhanced wheat yield and its components. ...
Increasing wheat output while decreasing the usage of chemical fertilizers is a significant policy considering the current economic conditions the world is going through. Thus, there is necessity for encourage eco-friendly techniques to add benefits to wheat growth and productivity while also reducing chemical fertilizers requisite. The current study was carried out to evaluate the impact of a potent strain (Nostoc calcicola), its extract, and compost tea solely or in combination on growth and productivity of wheat plants. The results support our hypothesis that the combined treatment significantly enhanced wheat growth, nutrients uptake, photosynthetic pigments, yield, and its components as well as the nutritional value of wheat grains and straw by using 50% dose of the required quantity of chemical fertilizers. Our findings suggested that combining cyanobacteria and compost tea to improve wheat plant growth, productivity and yield quality attributes might be a simple and cost-effective strategy.
... The highest increase was obtained with C75TNANEAE (N 75% + compost tea + Nostoc calicola, Anabaena cylindrica soil and extract) treatments. Additionally, using cyanobacteria strain found an increase yield component, this result is similar to those repoted by Karthikeyan et al. (2007) and El-Zemrany (2017) who reported the effects of inoculant cyanobacteria strains on wheat involving (single or in combination) showed visible differences in terms of the appearance of plants. This was accompanied by enhancement in plant height, dry weight and grain yield of wheat crop. ...
... Cyanobacteria are known to produce sugars, amino acids, auxins, vitamins, and phytohormones, which helps in stimulating plant growth (Karthikeyan et al., 2007;Misra and Kaushik, 1989;Obana et al., 2007;Rastogi and Sinha, 2009). In agriculture, cyanobacteria and cyanobacteria-based formulations are known to have several benefits as they improve soil stability (Peng and Bruns, 2019;Prasanna et al., 2021a), fix atmospheric nitrogen (Pereira et al., 2009;Singh, 1961;Venkataraman, 1972), provide protection against pests and diseases (Bao et al., 2021;Mahawar et al., 2020;Wiegand and Pflugmacher, 2005) , play an important role in the alleviation of salinity and drought (Sneha et al., 2021) and biofortification of plant parts, including produce (Nishanth et al., 2021a;Rana et al., 2012;Shivay et al., 2022). ...
Cyanobacteria and their biofilms are used as biofertilizing options to improve plant growth, soil fertility, and grain quality in various crops, however, the nature of metabolites involved in such interactions is less explored. The present investigation compared the metabolite profiles of cyanobacterial biofilms: Anabaena torulosa- Trichoderma viride (An-Tr) and A. torulosa- Providencia sp. (An-PW5) against the individual culture of A. torulosa (An) using untargeted gas chromatography-mass spectroscopy. Metabolites were identified using the NIST mass spectral library and the relative peak area of cultures analysed, after normalization with an internal standard, ribitol. An-Tr biofilm recorded approximately 66.85% sugars, with increased quantity and numbers of sugars and their conjugates, which included maltose, lactose, and D-mannitol, but decreased amino acids concentrations, attributable to the effect of Tr as partner. Heat map and cluster analysis illustrated that An-Tr biofilm possessed a unique cluster of metabolites. Partial least square-discriminate analysis (PLS-DA) and pathway analyses showed distinct modulation in terms of metabolites and underlying biochemical routes in the biofilms, with both the partners- PW5 and Tr eliciting a marked influence on the metabolite profiles of An, leading to novel cyanobacterial biofilms. In the An-PW5 biofilm, the ratios of sugars, lactose, mannitol, maltose, mannose, and amino acids serine, ornithine, leucine and 5-hydroxy indole acetic acid were significantly higher than An culture. Such metabolites are known to play an important role as chemoattractants, facilitating robust plant -microbe interactions. This represents a first-time study on the metabolite profiles of cyanobacterial biofilms, which provides valuable information related to their significance as inoculants in agriculture.
... Many detailed studies examining the effects of eukaryotic microalgae on soil in terms of impact on some hydrolytic enzymes show that inorganic P concentrations are increased due to increased phytase activity (Zhu and Wakisaka 2020). Microalgae have the ability to fertilize soil through polysaccharides and mucilage's secretions, which serve as C source (Karthikeyan et al. 2007;Kholssi et al. 2018;Ortiz-moreno et al. 2019). The application of microalgae leads to increased plant growth, reduces effects of saline stress on plants, and increases crop production (Chanda et al. 2019;Elarroussi et al. 2016). ...
depends to a great degree on soil characteristics — soil is the substrate which when managed properly can support
plant growth, but when abused requires additional inputs. Research is increasingly focused on the development of new
non-synthetic and non-fossil-based products having less impact on the environment and health. In this context, the use
of algae biomass (macro and micro) has been widely researched as a fertilizer for agricultural production as a “green
economy” alternative product. Currently, the production of marine algae far outstrips the production of microalgae and
its main use is for food consumption and some industrial applications. The cost of production is also variable, as marine
algae are usually cultivated in integrated multitrophic aquaculture systems. The production of microalgae involves
many variables, among them the species, the culture medium, obtaining process, final application, etc. and, based on
these, its production cost is estimated. Some researchers point out that the use of simplified technology and increased
production capacity tend to reduce operating costs within the ideal photosynthetic yield. This review sought to highlight
the importance of algae and their extracts as natural biofertilizers and biostimulants, as well as the mechanisms of action
and the possible relationship of these organisms with cultivated plants.
... Co-inoculation of plant growth promoting rhizobacteria along with cyanobacteria has also been reported to increase in plant growth and grain yield significantly [22]. Karthikeyan et al. [23] investigated potential of cyanobacteria on wheat along with different dose of chemical fertilizers, interestingly; all treatments showed enhanced plant growth and yield parameters. A study with Anabaena and Trichoderma viride biofilm showed 12-25% increase in yield of soybean as well as enhanced microbial activity. ...
Cyanobacteria are photosynthetic microorganisms and produce large number of diverse bioactive compounds. In the present study plant growth promotion and antifungal activities of fourteen cyanobacteria strains have been studied against selected phytopathogens. Among screened isolates highest production of IAA was found in Chroococcidiopsis cubana HC1 (102.9 µg/ml) when supplemented with 0.3 mg/mL tryptophan. Co-inoculation of C. cubana (HC1) and Tolypothrix sp. (RC1) were evaluated for plant growth promoting potential on rice (Rajendra Sweta) plant which showed enhanced root (20.7±1.0 cm) and shoot length (11.4±1.3 cm) as well as increased number of forks (36.0±1.0) as compared to control seedlings. Among fourteen isolates eight cyanobacterial isolates showed zone of inhibition against selected phytopathogens. Tolypothrix sp RC1 and Nostoc sp. SK1 showed highest rate of inhibition (50%) against Ralstonia solanaceram while Pseudoanabaena sp. RD1 showed highest inhibition rate (52%) against Sclerotium rolfsi. Nostoc sp. HC2 found to be highest inhibition (61%) against Fusarium oxysporum. The cyanobacteria reported in this study have immense potential for biocontrol against fungal plant pathogens and plant growth promoting ability which enhances crop growth. Cyanobacterial isolates obtained from the study could be worthy in sustainable agriculture due to dual advantages of biocontrol as well as plant growth promotion.
... In this regard, it is imperative to employ ecologically friendly techniques to lessen the negative impact of agro-chemicals, using microbebased products [3,4] . Numerous microorganisms are known to synthesize and secret growth-promoting chemicals that improve plant health through a variety of methods in addition to balancing mineral nutrition and naturally fertilizing the soils [5] . It is well known that in plants, pathological illnesses are brought by microbial pathogens or physiological disorders by abiotic stressors typically include damaging free radicalmediated oxidative degradation of biomolecules [6] . ...
Cyanobacteria are first oxygen evolving prokaryotic photosynthetic organisms used as biofertilizer in several crop fields and play a crucial role to increase crop yields. They were isolated and screened for several plant growth promoting activities like indole acetic acid (IAA) production, phosphate solubilization, exopolysaccharide (EPS) production and their impact on seed germination, vigour index and root/shoot ratio (R/S ratio) of paddy plant. Isolated cyanobacteria Nostoc calcicola, N. punctiforme, N. linckia and Anabaena oryzae was identified using standard monographs. Paddy seeds were treated with different cyanofilterats in which N. punctiforme showed highest 97.33% seed germination while N. calcicola showed 90.66% and control (soaked in DDW) showed only 88% seed germination. Maximum vigour index was showed by N. linkia i.e., 988.26. IAA production was found 0.88 µg/ml in case of N. calcicolawhile phosphate solubilization 94.3 µm in diameter was maximum in N. punctiforme followed by 75 µm, 47.9 µm, 30.7µm in N. calcicola, N. linckia and A. Oryzae, respectively. EPS production was highest in A. oryzae i.e., 0.205 µl/ml and minimum in N. linckia which is 0.108 µl/ml. The data of our study showed that inoculation of these cyanobacterial species to paddy seedlings appear a potential candidate to promote seed germination, vigour index and R/S ratio of paddy plant. These results encourage use of A. oryzae, N. calcicola, N. linckia and N. punctiforme as biofertilizer for rice crop to enhancing growth without using harmful chemical fertilizers.
... In line with this, improvements in wheat yield and its components under the acceptable increasing N rates were reported by Sticksel et al. (2000). As for the effect of cyanobacteria, this result is similar to those repotted by Karthikeyan et al. (2007) and El-Zemrany (2017) who reported the effects of inoculant cyanobacterial strains on wheat involving (single or in combination) showed visible differences in terms of the appearance of plants. This was accompanied by enhancement in plant height, dry weight and grain yield of wheat crop. ...
... Many detailed studies examining the effects of eukaryotic microalgae on soil in terms of impact on some hydrolytic enzymes show that inorganic P concentrations are increased due to increased phytase activity (Zhu and Wakisaka 2020). Microalgae have the ability to fertilize soil through polysaccharides and mucilage's secretions, which serve as C source (Karthikeyan et al. 2007;Kholssi et al. 2018;Ortiz-moreno et al. 2019). The application of microalgae leads to increased plant growth, reduces effects of saline stress on plants, and increases crop production (Chanda et al. 2019;Elarroussi et al. 2016). ...
Due to intensive agricultural practices, agricultural lands are subject to continuous degradation. Agricultural productivity depends to a great degree on soil characteristics. Soil is the substrate which when managed properly can support plant growth, but when abused requires additional inputs. Research is increasingly focused on the development of new non-synthetic and non-fossil-based products having less impact on the environment and health. In this context, the use of algae biomass (macro and micro) has been widely researched as a fertilizer for agricultural production as a "green economy" alternative product. Currently, the production of marine algae far outstrips the production of microalgae and its main use is for food consumption and some industrial applications. The cost of production is also variable, as marine algae are usually cultivated in integrated multitrophic aquaculture systems. The production of microalgae involves many variables, among them the species, the culture medium, obtaining process, final application, etc. and, based on these, its production cost is estimated. Some researchers point out that the use of simplified technology and increased production capacity tend to reduce operating costs within the ideal photosynthetic yield. This review sought to highlight the importance of algae and their extracts as natural biofertilizers and biostimulants, as well as the mechanisms of action and the possible relationship of these organisms with cultivated plants
... Cyanobacterial inoculation helps to increase rice crop yields (grain yields) to the extent of 10-24% in diverse locations in the world, especially in South Asia [44]. ...
After the green revolution, there has been a substantial increase in the productivity of food crops. But the nutritional aspect of crops could not keep pace with the growing demand of the population. This has led to a rise in malnutrition problems, especially in developing countries, due to a lack of balanced nutrition. Agronomic biofortifica-tion, the process of increasing micronutrient content in food crops through agronomic approaches, is seen as an important process to improve the status of malnutrition in the world. It is seen as a quick, safe, and cost-friendly approach to provide iron, zinc, and other micronutrients in our everyday diet. Unlike molecular/genetic approaches, agro-nomic biofortification is done on existing crops and varieties and hence the product is easily accepted by the consumers. Approaches like integrated nutrient management (INM) based on soil test values, microbial application, foliar spray of nutrients, can substantially increase the level of micronutrients, vitamins, folic acid, etc. in our food. With sufficient research interventions and awareness programs, agronomic biofortifi-cation can serve as a tool to improve the nutritional status of the world.
... Though, in rice ecosystem the importance of cyanobacteria for succouring the fertility and productivity is beyond words as these cultures scale down the dose of fertilisers in input intensive rice based cropping system and making it more eco-friendly and profitable. Other than, NUE or fertiliser saving cyanobacteria secretes indole-3 acetic acid stimulates the microbial folk in soil particularly in rhizosphere aiding the roots to forage N form the soil (Karthikeyan et al., 2007;Spaepen et al., 2007). ...
... The role of photosynthetic microbes for CO 2 sequestration is of emerging interest as they are autotrophs and use sunlight and CO 2 . Among them, diazotrophic cyanobacteria help in savings of nitrogenous fertilizers, and also improve plant growth and soil fertility [26,47]. As they utilize CO 2 for photosynthesis and evolve oxygen it can be a potential sink for atmospheric CO 2 [48]. ...
Climate change affects nitrogen dynamics in crops and diazotrophic microorganisms with carbon dioxide (CO2) sequestering potential such as cyanobacteria can be promising options. The interactions of three cyanobacterial formulations (Anabaena laxa, Calothrix elenkinii and Anabaena torulosa–Bradyrhizobium japonicum biofilm) on plant and soil nitrogen in soybean, were investigated under elevated CO2 and temperature conditions. Soybean plants were grown inside Open Top Chambers under ambient and elevated (550 ± 25 ppm) CO2 concentrations and elevated temperature (+2.5–2.8°C). Interactive effect of elevated CO2 and cyanobacterial inoculation through A. laxa and Anabaena torulosa–B. japonicum biofilm led to improved growth, yield, nodulation, nitrogen fixation, and seed N in soybean crop. Nitrogenase activity in nodules increased in A. laxa and biofilm treatments, with an increase of 55% and 72%, respectively, over no cyanobacterial inoculation treatment. Although high temperature alone reduced soil microbial biomass carbon, dehydrogenase activity, and soil available N, the combined effect of CO2 and temperature were stimulatory; cyanobacterial inoculation further led to an increase under all the conditions. The highest seed N uptake (758 mg plant−1) was recorded with cyanobacterial biofilm inoculation under elevated CO2 with control temperature conditions. The positive interactions of elevated CO2 and cyanobacterial inoculation, particularly through A. laxa and A. torulosa–B. japonicum biofilm inoculation highlights their potential in counteracting the negative impact of changing climate along with enhancing plant and soil N in soybean.
... Though, in rice ecosystem the importance of cyanobacteria for succouring the fertility and productivity is beyond words as these cultures scale down the dose of fertilisers in input intensive rice based cropping system and making it more eco-friendly and profitable. Other than, NUE or fertiliser saving cyanobacteria secretes indole-3 acetic acid stimulates the microbial folk in soil particularly in rhizosphere aiding the roots to forage N form the soil (Karthikeyan et al., 2007;Spaepen et al., 2007). ...
Soil fertility management has two requirements: establishing and maintaining the soil pH and essential plant nutrient elemental content within their desired ranges for that soil type and crop or cropping sequence, with its associated cultural management practices. It is obvious that none of the soil fertility management systems will meet all these requirements. However, there are basic principles that do apply, requiring moderate modification to suit the specifications of soil type, crop species, and climatic/weather characteristics. Management requirements for achieving a moderate yield and average product quality, require fewer inputs and skill requirements than those required for achieving maximum yield and highest product quality, the latter not allowing for errors in procedural practices. For most cropping situations, the maximum biological yield potential based on the combination of soil and plant parameters is unknown. It is also not possible to advance quickly from a moderate soil fertility/plant nutrition status to one that results in high yield or quality product achievement. Those management practices applied to one set of soil, plant, or climatic conditions are not applicable to all ranges of conditions. Hence, this chapter tends to discuss the problems of soil fertility and productivity, nutrients and mining and imbalance, and inadequate plant nutrients supply in Nigeria’s agriculture, as well as the problems affecting the use of chemical fertilizers, the types, and role of organic sources of plant nutrients. Finally, a case will be made for integrated nutrient supply that combines chemical fertilizers with biological and organic sources.
... The contribution of algae in agriculture is untold as they are the biological promoters of crop growth. Specifically, microalgae promote the growth of beneficial bacteria, improve soil organic carbon contents, make atmospheric nitrogen available to the soil, produce growth hormones, and prevent plant diseases (Fogg 1949;Karthikeyan et al. 2007;Swain et al. 2017). The photosynthetic rates of algae are ideal for trapping CO 2 , thereby removing the excess CO 2 from the atmosphere. ...
Algae are photosynthetic prokaryotic or eukaryotic ubiquitously found group of organisms. Their enormous potentiality in coping up with various environmental crises has been well documented. Algae have proven to be ideal for biomonitoring of water pollution and help in removing the pollutants with their process of bioremediation apart from the production of eco-friendly sources of energy. Industries like food and pharmaceuticals are exploiting algae for producing several value-added products. The agricultural sector is also highly benefited from microalgae, as they are the good promoters of crop growth. The CO2-removing potential of algae proves to be an asset in fighting climate change. Moreover, the relatively easy and inexpensive methods of sampling and culturing of algae make them more popular. In this paper, we review the sustainable application aspects of algae in various areas like pollution control, energy production, agriculture, and fighting climate change. Critical discussions have been made on the recent trends and advances of algal technologies indicating future prospects.
Microphytes incorporate several characteristics that are becoming increasingly important in a complex farming setting and the process of land reclamation. Microalgae/microphytes boost soil productivity and structure by adding minerals and improving microbial soil quality metrics and nutrient cycling. Protecting
plants from disease, producing phytohormones and other bioactive compounds, and associating with plant roots are the ways through which microalgae contribute to plant development. These results are significant as they could lead to further
advancements in the discovery of substances that can boost growth or the development of crops that do not need nitrogen. Microalgae have massive untapped capabilities as natural assets in agriculture and as sustainable answers for agricultural
production, plant macro- and micronutrient enrichment, and soil preservation and regeneration due to their extensive range of available forms and functions. Future farming viability relies heavily on ecosystem functions like soil fertility, nutrient cycling, and controlling erosion. All these can be controlled by using
microalgal resources. Microphytes not only improve soil and plant characteristics but also decrease the resulting waste supplied to the soil and plants. This involves implementing environmentally friendly and socially responsible practices to ensure long-term agricultural productivity and ecosystem health. These practices
contribute to achieving the UN Goals of Sustainability by promoting sustainable agriculture, ensuring food security, reducing environmental impacts, and supporting the well-being of both present and future generations.
Due to the global increase in the world population, it is not possible to ensure a sufficient food supply without additional nitrogen input into the soil. About 30–50% of agricultural yields are due to the use of chemical fertilizers in modern times. However, overfertilization threatens biodiversity, such as nitrogen-loving, fast-growing species overgrow others. The production of artificial fertilizers produces nitrogen oxides, which act as greenhouse gases. In addition, overfertilization of fields also releases ammonia, which damages surface waters through acidification and eutrophication. Diazotrophic cyanobacteria, which usually form a natural, stable biofilm, can fix nitrogen from the atmosphere and release it into the environment. Thus, they could provide an alternative to artificial fertilizers. In addition to this, biofilms stabilize soils and thus protect against soil erosion and desiccation. This chapter deals with the potential of cyanobacteria as the use of natural fertilizer is described. Possible partners such as plants and callus cells and the advantages of artificial co-cultivation will be discussed later. In addition, different cultivation systems for studying artificial co-cultures will be presented. Finally, the potential of artificial co-cultures in the agar industry will be discussed.
The continuous growth of the world population has imposed major challenges on agriculture. Consequently, farmers generalized the overuse of synthetic fertilizers and pesticides to meet the global food demand. Although these products have helped many developing countries increase their crop yield, they have simultaneously resulted in many issues, mainly the decline of soil fertility and degradation of local ecosystems due to soil, water, and air contamination, combined with their non-renewable nature and increased costs. For agriculture to become more sustainable, the use of alternative biological products, with recognized beneficial effects on plant yield and health, must be expanded. In this context, microalgae and cyanobacteria are rich sources of nutrients and bioactive metabolites, which have been gaining attention from researchers and companies for their ability to improve plant nutrition, growth, and tolerance to stress. This review gives an overview of the research work that has been done in the last two decades, regarding the use of microalgae and cyanobacteria (blue-green algae) as biofertilizers, biostimulants, and biopesticides. This work identified trends and challenges and highlights the use of microalgae to recycle the nutrients from wastewater to improve plant productivity while reducing the fertilizer and water footprint for more sustainable agriculture practices.
Many microorganisms live in the form of a biofilm. Although they are feared in the medical sector, biofilms that are composed of non-pathogenic organisms can be highly beneficial in many applications, including the production of bulk and fine chemicals. Biofilm systems are natural retentostats in which the biocatalysts can adapt and optimize their metabolism to different conditions over time. The adherent nature of biofilms allows them to be used in continuous systems in which the hydraulic retention time is much shorter than the doubling time of the biocatalysts. Moreover, the resilience of organisms growing in biofilms, together with the potential of uncoupling growth from catalytic activity, offers a wide range of opportunities. The ability to work with continuous systems using a potentially self-advancing whole-cell biocatalyst is attracting interest from a range of disciplines, from applied microbiology to materials science and from bioengineering to process engineering. The field of beneficial biofilms is rapidly evolving, with an increasing number of applications being explored, and the surge in demand for sustainable and biobased solutions and processes is accelerating advances in the field. This Review provides an overview of the research topics, challenges, applications and future directions in beneficial and applied biofilm research.
Micronutrient delivery can be made more sustainable, affordable, and long lasting through the process of biofortification, which involves breeding nutrients into food crops. The purpose of the biofortification strategy is to introduce a nutrient-dense micronutrient trait into cultivars that already have other desirable agronomic and dietary features, such as high yield and disease resistance. Crop surpluses may find their way into retail stores, where they will likely reach first rural consumers and later urban consumers. Here, we review the experiences from the past and different strategies for future food security, such as maintaining the physical, chemical, and biological characteristics of healthy soil and following proper cultivation practices, including tillage, water management, integrated and balanced nutritional management, the application of organic matter, the application of synthetic fertilizers, micronutrient and bioavailability applications, the application of microorganisms, crop rotations, intercropping, and proper pest management. This chapter also discusses how to build awareness, policy-supported research interventions, crop development, transgenic approaches, and low-cost, high-throughput methods. Although biofortification is not yet being fully scaled up in a single nation, a wealth of data and many experiences point to its potential usefulness. Biofortification will become a cost-effective more-nourishing investment thanks to policies that enable cross-sectoral implementation at all levels.
The scientific evidence on applications of microalgae in bioremediation of wastewaters, increasing agricultural productivity, and biomass production strengthens their potential in supporting global socioeconomic and environmental sustainability. Microalgae can consume organic compounds and pollutants present in domestic, agricultural, and industrial wastewater. This leads to biomass production in wastewater and water being relatively safe to be disposed of into water bodies and safeguard life in water. The extensive diversity of microalgae, encompassing a distinct array of physiological, reproductive, and functional traits, along with their remarkable efficiency in wastewater treatment, positions this group of organisms as exceptionally superior to other organisms. Molecular and biotechnological approaches have provided promising tools for improving the biomass production of microalgae from wastewater. Recent technological innovations have facilitated harvesting algal biomass from wastewater treatment plants for developing a range of bioproducts like bioenergy, biofertilizer and other various high value biochemicals. Microalgal communities and their biomass produced from wastewater are investigated for the restoration of degraded lands. The potential use of diverse microalgal species and their biomass from wastewater for restoration of degraded lands such as salt-affected lands, drought ridden arid areas, fly ash contaminated lands, and metal-polluted mine spoils is discussed. Moreover, this review elaborates on how use of microalgae from wastewater to wastelands can contribute to various sustainable development goals (SDGs). It is found that extending microalgae research and use from wastewater to wastelands can support achieving all SDGs by directly contributing to 10 goals.
The primary means of nutrient uptake for cyanobacteria is oxygen-producing photosynthesis. Their ecological variety is astounding; they occupy a very wide range of lighted ecological niches in terrestrial, marine, and freshwater habitats. Despite this apparent metabolic consistency, they exhibit tremendous phylogenetic diversity. The fact that cyanobacteria have certain physiological and metabolic traits that are exclusively seen in prokaryotes significantly broadens this spectrum. The capacity to fix nitrogen in an aerobic manner under light is a special characteristic. Apart from Gonotheca species, all aerobic, nitrogen-fixing cyanobacteria—a structurally diverse group—produce heterocyst, the highly specialised cells that allow them to fix nitrogen efficiently in a fully aerobic environment by preventing the oxygen-sensitive enzyme nitrogenase from being inactivated quickly in vivo (Hazelton, 1978; Stanier and Cohen-Bazire, 1978; Stewart, Haystead, and Pearson, 1969). The same quantities of cyanobacteria could be isolated from freshwater using a technique using nutrient-saturated glass fibre filters, but the quantity of accompanying heterotrophic bacteria was reduced by 2- to 15-fold. a broad-spectrum antibiotic called imipenem. In comparison to some other Plactam antibiotics, the B-lactam antibiotic that inhibits peptidoglycan biosynthesis, was more effective at lowering the levels of heterotrophic bacterial contaminants associated with newly isolated cyanobacteria to a point that made it easier to grow axenic cyanobacterial cultures.
Two heterocystous cyanobacteria strains, belonging to the genera Anabaena and Nostoc isolated from sandy and clay soil samples, soils were collected from superficial surface crust at El-Ismailia Research Farm, El-Ismailia Governorate, (30°35'41.901''N, 32°16'45.834''E) and Sids Res. Farm Beni Sweif Governorate, (29°4'54.349''N, 31°5'25.775''E), Agric. Res. Center, Egypt. Cyanobacteria strains were tested for their ability to form tight associations with the roots of wheat seedlings (15 days old) under Lab. conditions. Both Nostoc muscorum and Anabaena variabilis and /or their mixed culture were inoculated to wheat seedlings. Nostoc muscorum was able to form close associations with wheat plants, and was able to enter through root hairs and penetrate the epidermal layer of wheat roots. While, Anabaena variabilis formed loose association with wheat seedling roots. The mixture of both cyanobacteria strains formed weak association with root of wheat seedlings. The tight association of Nostoc muscorum with the roots of wheat seedling resulted in the accumulation of Chlorophyll a in wheat roots and also exhibited nitrogenase activity by the roots. The tight association of Nostoc muscorum increased significantly the dry weight of seedlings plants. In contrast, Anabaena variabilis formed loose association against weak association for the mixture of both Nostoc muscorum and Anabaena variabilis.
Microalgae are a source of scientific curiosity and inspiration for their utilization as ‘inoculants’ in agriculture and the commercial production of high-value products. Their diversity and abundance in the soil environment highlight the fact that these integral members of the soil microbial community modify the physical and chemical conditions of soils and interact with other microorganisms and even with higher plants with varying degrees of association. However, to date, the agronomic benefits of the nitrogen fixation trait of cyanobacteria have not been fully realized. Thus, the ecological functions of these organisms in the biological soil crusts should be thoroughly evaluated and widely applied given that climate change events can increase desertification. Currently, the crop yield increments and pest control due to these biostimulants and the reclamation of saline and sodic soils by these bioameliorants are considered economically marginal. Similarly, the carbon capture and storage by eukaryotic microalgae and cyanobacteria in soils are poorly understood. Limitations in their commercial production for agricultural use include inadequate technological innovations and the enormous expectation for yield increments, together with the contemporary monetization of their environmental benefits. Thus, this critical review presents the desirable reappraisal of their agronomic benefits and the invigoration of research and culture collections to utilize these organisms or their metabolites, considering the evolutionary consequences and environmental advantages and finally their commercial production for widespread application in agriculture.
Phyllosphere which is mostly the above-ground plant surface harbours a diverse group of microorganisms and interacts with the host providing beneficial effect in terms of protection and plant growth. These aerial colonizing microorganisms are known as epiphytes. The most predominating epiphytes include bacteria and fungi which have a mutualistic, commensals, and antagonist's relationship with the host plant promoting its growth, providing tolerance to various stresses utilizing the habitat provided by the plant and managing the invading pathogen. Even though many research have been carried out regarding presence of epiphytes in different region of phyllosphere providing beneficial effect to plant health, most of the studies have been restricted to only the microbiome present on the leaves. Therefore, insight analysis and more understanding are needed with them to know the dynamic association between microbiome and host so that their implication can fulfil the issues created by the chemical pesticide and could set off new strategies for sustainable plant protection and growth. In this chapter, we have highlighted particularly different types of phyllosphere, microorganisms inhibiting the phyllosphere, working strategies, adaptation features and their importance.
The use of livestock and poultry manures as fertilizers is regarded as an important action in the development of circular agriculture. However, long-term fertilization with manure is accompanied with heavy metals accumulation, pathogens contamination, and ammonia toxicity, which may cause the decline of soil quality and crop productivity. To address the aforementioned problems, in this work, we proposed a “manure-algae-crop” technical route, in which microalgae are employed as a carrier transporting nutrients in manures to soil and crops. This paper presented the advanced techniques which can tackle with the hazardous factors in manures and promote the nutrients assimilation by microalgae. Additionally, the utilization of microalgae in the forms of living cyanobacteria, liquid fertilizer, and slow-release fertilizer was discussed in detail. Particularly, we also focused on the disadvantages of algae fertilizers in different forms. By the end of this work, based on the analysis of current challenges and problems, we discussed the potential solutions and prospects of “manure-algae-crop” technical route.
In fact, previous studies have achieved many progresses in algae-based manure remediation and utilization of algae fertilizers. Hence, based on current knowledge, “manure-algae-crop” technical route has greater advantages over traditional models of manures utilization in agriculture. In the foreseeable future, with the development of new technologies, reduction of operational cost, and upgrading of agricultural model, “manure-algae-crop” technical route will be applied more frequently in agriculture. It is expected that this technical route can truly promote the high-value utilization of manures and the development of eco-friendly agriculture.
In the context of climate change, the use of microalgae is an alternative to meet the requirements of agriculture, food and renewable energy. A major area of application is the use of microalgae as biofertilizers in agriculture. The aim of this paper is to study the influence of the application of Chlorella sorokiniana UTEX 1230 inoculum on the evolution of soil chemical composition, as well as the ability of microalgae, as a biofertilizer, on the growth and development of tomato plants, including the influence on plant physiological indices. Ground determinations, at 60 days after application of Chlorella sorokiniana UTEX 1230 inoculum indicated higher values of nitrogen, phosphorus, potassium and organic carbon content in the soil, The results regarding the growth and development of the plants obtained in the protected area (solar greenhouse), for the Romec 554j tomato variety showed differences between the variants studied. The Romec 554j tomato variety recorded a higher rate of photosynthesis in the version treated with the inoculum of Chlorella sorokiniana UTEX 1230, compared to the control version and the technologically fertilized version (12,66 µmol CO2 / m2 / s, compared to 11,82 µmol CO2 / m2 / s in the control version and 12,48 µmol CO2 / m2 / s in the technologically fertilized version), but the values were not statistically assured.
The importance of cyanobacteria has increased tremendously due to their unique capabilities including ubiquitous presence, short generation time and the ability to fix atmospheric nitrogen. Cyanobacteria are considered to be a rich source of novel metabolites that are of great importance from an agricultural and industrial point of view. The worldwide increase in population seen over the last decades has contributed to the increasing demand for food supplies, which can only be achieved through improvements in agricultural productivity. Cyanobacterial biomass is an effective biofertilizer source for improving agricultural productivity by boosting soil physicochemical characteristics including mineral nutrient status and water holding capacity of demeaning lands. Environmental quality can also be increased by applying cyanobacteria as a bio-inoculant. They are also being used in the industrial and domestic wastewater treatments for the removal of phosphate, ammonia and other heavy metals such as Cu, Fe, Cr, Ni and Mo. The photoprotective role of cyanobacteria is another important application in industrial sectors. Cyanobacteria have been genetically designed with novel genes to
produce many biofuels such as biodiesel, bio-hydrogen and bio-methane.
The role of cyanobacteria as food products and biofertilizer in
agricultural sectors has prompted researchers to come up with welldefined
applications of cyanobacteria. This chapter is an attempt to enlist
useful facts about cyanobacteria and their possible role in resolving the
agricultural as well as industrial issues in the future welfare of the world.
Due to the exploding world population, there is a tremendous increase in demand for agricultural output, which has resulted in the pressure for large-scale crop production. Therefore, chemical fertilizers are used extensively to increase the agricultural output, which has caused hazardous effects on human health, soil quality, and the environment. To combat these problems, beneficial microbes have been exploited and used as biofertilizers. It has been well documented that certain microorganisms including bacteria, fungi, and cyanobacteria have plant growth promoting properties and can be safely used as alternative sources of fertilizer. These microbes when used in combination with crop residues and compost show better results in terms of crop yield and soil fertility. The chapter highlights the potential use of various types of biofertilizers in sustainable agriculture with special emphasis on their beneficial role in nutrient uptake, plant growth promotion, and protection against several plant pathogens in an eco-friendly manner.
Recent application of modern agricultural biotechnologies and use of high-yielding crop varieties provided sufficient crop yields and food for human population. But, the major constraint to enhance crop yield and food production is the availability of various nutrients in the soil, which include nitrogen, phosphorus, potassium, sulphur, zinc and other micronutrients. Currently, chemical fertilizers and plant growth regulators are widely utilized for obtaining high crop yields. However, the injudicious application of fertilizers along with other agrochemicals has resulted in environmental pollution along with deleterious effects on beneficial microflora and fauna. Recently, soil-inhabiting beneficial microorganisms are screened and exploited for use as biofertilizers to enhance soil fertility and crop yield with reduced application of chemical fertilizers. Thus, the use of microbial inoculants has emerged as novel agrobiotechnology for attaining sustainable agricultural production systems. These beneficial microorganisms contribute immensely towards management of plant nutrients in the soil by way of nitrogen fixation, solubilization of phosphorus, potassium and zinc along with other nutrients. Other beneficial characteristics of microbial inoculants include phytohormones production, inhibition of phytopathogens’ growth, bioremediation of pollutants and heavy metals, and amelioration of abiotic as well as biotic stresses. However, the efficacies of microbial inoculants in improving crop yield under field conditions remain variable under varied farming situations in different agro-ecosystems. Recently, genetic engineering techniques are being employed to improve the beneficial traits in plants and microorganisms to improve nutrient availability, soil fertility and crop yield. In addition, identification of effective microbial inoculants and their persistence in soil and quality of these inoculants is a never-ending process for harnessing desirable impacts on crop productivity. Considering the importance of beneficial microorganisms in biogeochemical cycling of nutrients, various mechanisms involved in improving nutrients availability are reviewed for increasing food production.
(i)
Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
(ii)
Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
(iii)
Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
(iv)
Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.
Blue-green algal (Nostoc muscorum) or bryophyte (Barbula recurvirostra) growth on the surface of a brown earth silt loam contained in flooded columns significantly increased soil C (+20.9% and 23.0%, respectively) and soil N (+25.1% and +9.6%, respectively) after 5 weeks in the surface 0.7-cm soil layer. Differences in the lower layers were not significant since there was no movement of C or N metabolites down the profile, even after 21 weeks. The input of C by the inoculated blue-green algae was estimated at 0.48 Mg C 100-1 g soil or 0.45g C ha-1; the bryophyte growth gave 0.5 Mg C ha-1. N fixation by the blue-green algae alone was estimated at 60 kg N ha-1 after 5 weeks of growth. Blue-green algae associated with bryophyte growth had fixed 23 kg N ha-1 after 5 weeks, rising to 40 kg ha-1 after 21 weeks. Decomposition of the bryophyte biomass led to a significant increase in the dry weight (+16.8%) and the N uptake (+27.5%) of spring oil-seed rape planted in homogenised soil. In contrast, soil incorporation of the blue-green algal biomass had no significant effect on yield. The equivalent mineralized N from the blue-green algal and bryophyte incorporation was estimated as 24 and 58 kg N ha-1, respectively.
(i)
Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
(ii)
Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
(iii)
Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
(iv)
Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.
Two cyanobacterial soil isolates, Nostoc 2S9B and Anabaena C5, that had previously been shown to form different types of association with the roots of wheat plants grown in liquid culture, were tested for heterotrophic nitrogenase activity and the ability to colonize the roots of plants grown in sand. Nostoc 2S9B showed substantial nitrogenase activity when associated with the roots of plants grown in liquid culture in medium free of combined N, even with the roots maintained and with assays performed in the dark (29 % of the rate shown by root-associated Nostoc 2S9B grown and assayed in the light). When grown heterotrophically in the dark, at the expense of fructose, free-living Nostoc 2S9B showed a similar nitrogenase activity to root-associated Nostoc 2S9B in the dark. In contrast, Anabaena C5 showed no nitrogenase activity in the dark, under these conditions.
When three different wheat cultivars were grown in sand that had previously been surface-inoculated with Nostoc 2S9B or with the cultured symbiotic cyanobacterium Nostoc LBG1, isolated from the bryophyte Anthoceros, there was colonization of the plant roots; there was no colonization of roots by Anabaena C5 under these conditions. Some increases in plant biomass and nitrogen content were observed, but these were dependent on the wheat cultivar and cyanobacterial inoculum used.
Wheat plants grown in sand that had been pre-inoculated with Nostoc 2S9B, Nostoc LBG1 or Anabaena C5 in medium free of combined N had lower δ15N values in both roots and shoots than plants grown under identical conditions without a cyanobacterial inoculum. The observed 15N/14N fractionation indicates that N2 fixed by the cyanobacteria contributed to the nitrogen economy of the wheat plants, irrespective of whether they were closely associated with the plant roots.
The effects of usual or recommended rates of application of five organic amendments (24 t/ha·yr of MSW compost, sewage sludge, and ovine manure, 2.4 t/ha·yr of vermicompost, and 100 l/ha·yr of a commercial humic acids solution) on the microbial biomass content and level of selected enzymatic activities (dehydrogenase, alkaline phosphomonoesterase, phosphodiesterase, arylsulphatase, and urease) in soil, were evaluated in a long-term field experiment. Four and five years after the beginning of applications, neither vermicompost nor the humic acids solution showed any significant effect, suggesting that rates recommended by the producers and imposed by their high prices are too low to be useful. Owing probably to more realistic application rates, the highest values of all parameters studied were found when organic residues were applied, effects reaching statistical significance in most cases. MSW compost was the product yielding greatest enhancement of soil enzymatic activity, ovine manure and sewage sludge giving lower, but comparable results. Most of the parameters studied were found to be highly correlated, indicating a balanced enhancement of soil biological activity after the application of organic residues.
summaryThe infrastructure of a novel association between a N2-feeing cyanobacterium, Nastoc sp, isolated from soil, and wheat seedlings grown in liquid culture is described. Cyanobacteria were found either as hormogonia, filaments or aseriate packages. The aseriate packages, which developed from filaments, often formed a thick layer surrounding the root surface. The packages were in intimate contact with adjacent root epidermal cells and could not be removed without damaging the epidermis. Cyanobacteria penetrated both the root epidermis and cortex and formed packages in intercellular spaces. Cyanobacteria] filaments were occasionally found within plant cells that appeared empty. Additionally, cyanobacteria were observed in association with the stem and on the surfaces of leaves. These findings demonstrate the technical feasibility of forming a novel association between a N2-fixing cyanobacterium and a cereal.
The present observation indicates that, besides the nitrogenous compounds, other biologically active cell constituents like vitamin B12 and auxins may also appreciably contribute to the fertilizing action of the nitrogen-fixing blue-green algae. Of the various intracellular amino acids of Cylindrospermum muscicola, cystine, tyrosine and phenylalanine seem to be available to the rice plants. The alga can synthesize vitamin B12 active compounds, the yield of which was about 1.2 to 1.5μg/g dry weight of the alga. The synthesis of these compounds was promoted by the addition of cobalt salt. The alga also contains interconvertible auxin-like substances which stimulate the root growth of rice seedlings.
summaryA variety of heterocystous, N2-fixing cyanobacteria, isolated from soils, were identified as members of the genera Nostoc, Anabaena and Cylindrospermum. These isolates were tested for their ability to form associations with the roots of wheat seedlings grown in liquid culture. Two types of associations were recognized: loose associations with cyanobacterial filaments growing between root hairs, which were typical of the Anabaena isolates, and tight associations of microcolonies in intimate association with the root surface, which were restricted to certain Nostoc isolates. Differences in nitrogenase activities of the free-living and associated cyanobacteria, together with the effects of added nitrate, indicate that nitrogenase activity may be influenced by the plant and/or its products.
The effect of extracellular products fromAulosira fertilissima on the growth of rice seedlings (IR-8) has been studied. There is indication of liberation of a root-promoting hormone from the alga. The growth pattern of rice seedlings, treated with algal filtrate, parallels that of seedlings treated with gibberellic acid. An increased growth of rice seedlings results when they are treated with algal filtrate obtained from the exponential phase of the alga. The amino acid-treated seedlings do not show any marked increase in growth. Filtrate fromAnacystis nidulans, on the other hand, do not show any growth promoting response. The possibility of liberation of kinins byA. fertilissima does not appear to be involved.
N2-fixing blue-green algae (Cyanobacteria), besides enriching soils with N and organic carbon, may modify a number of chemical and electro-chemical properties of the soils resulting in a change in availability of some micronutrient elements. Keeping this in view, an experiment was conducted to study the effects of growth and subsequent decomposition of blue-green algae on changes in the different forms of Fe and Mn in four soils under submerged condition. A mixed algal culture containing Anabaena, Nostoc, Cylindrospermum, and Tolypothrix was used as inoculum. It was allowed to grow for 2 months, after which the soils were sequentially extracted with (i) M NH4OAc (pH 7.0), (ii) M K4P2O7, (iii) 0.1 M NH2OH.HCl (pH 2.0), (iv) 0.2 M (NH4)2C2O4 (pH 3.0) and (v) 0.1 M ascorbic acid to obtain water-soluble plus exchangeable, organically bound, easily reducible, amorphous oxides-and crystalline oxides-bound forms of Fe and Mn, respectively, both during the growth as well as the subsequent in-situ decomposition of the algal biomass in soils. Iron and Mn in the extracts were estimated by atomic absorption spectrophotometry.
The results showed that growth of blue-green algae in submerged rice soils caused a decrease in the NH4OAc-extractable forms of Fe and Mn with concomitant increases in all the other four determined forms of the elements. Such decreases and/or increases in different forms of Fe and Mn in soils were explained as being due to release of O2, addition of organic matter and liberation of extracellular organic compounds by the blue-green algae during their growth. The decomposition of algal biomass resulted in an increase in the NH4OAc-, K4P2O7- and (NH4)2C2O4-extractable forms of Fe and Mn with a simultaneous decrease in the NH2OH · HCl- and ascorbic acid-extractable forms. Development of strong reducing conditions and formation of organic acids with chelating properties were suggested as being the cause of the above changes. The implication of these changes in the forms of Fe and Mn for the Fe and Mn nutrition of rice plants were discussed.
Following co-cultivation of wheat with N2-fixing cyanobacterial isolates capable of forming associations, Nostoc 2S6B, 2S9B or Anabaena C5, for 15 days in the presence or absence of combined N a large stimulation of root length was observed without any increase in root dry weight. Increases in the N concentrations of both roots and shoots occurred following co-cultivation with most cyanobacteria tested. The increase in plant N concentrations appeared to be dependent on the wheat cultivar and the cyanobacterial isolate used. Nostoc isolates had similar nitrogenase activities when associated with roots and when grown in shake-flask cultures. The nitrogenase activity of roots colonized by Anabaena C5 or Nostoc 2S6B was higher following removal of loosely associated cyanobacteria.
Growth of wheat in a nitrogen-free hydroponic co-culture with a mutant strain of the cyanobacterium Anabaena variabilitis (strain SA-1) was enhanced over plants grown with the parent strain SA-0. This increase was achieved in the dry weight, grain yield, and total nitrogen content of the plants. Nitrogenase activity of the mutant strain SA-1 was increased in a co-culture of the cyanobacterial mutant with wheat plants compared to the activity of the wild-type strain in association with wheat.
A rapid, inexpensive adaptation of the fumigation-extraction method for estimating the soil microbial biomass based on the fact that certain molecules absorb in the near ultraviolet (UV) region of the electromagnetic spectrum is described. A highly significant, positive linear relationship (r=0.94***) between biomass C as measured by fumigation-extraction, and estimates of the microbial biomass organic matter as measured by UV absorbance at 280 nm was obtained. Similarly, highly significant relationships were obtained between UV estimates of the microbial biomass and biomass total N and biomass ninhydrin-reactive N (r =0.91*** and r=0.92*** respectively).
Summary1.Atmospheric nitrogen-fixing blue-green algae-Tolypothrix tenuis (from Borneo), Calothrix brevissima (from the Palau Islands), Anabaenopsis sp. (from Sumatra) and Nostoc sp. (from Java)—were cultivated in a pure, bacteria-free condition.2.The cultural solution contained K2HPO4, MgSO4·7H2O, CaCl2, FeCl3, and glucose, and did not contain any N compound. Therefore, on the basis of the results obtained it is to be concluded that these organisms are able to fix atmospheric nitrogen.3.The amino acids contained in the external solution as well as in algal cells were examined by paper-partition chromatography. Although many amino acids are found in the algal cells, the external solution is poor in amino acids or lacks them. Only Calothrix brevissima secreted aspartic acid, glutamic acid, and alanine into the external cultural solution.
Theory And Practice in Experi-mental Bacteriology
- G C Meynell
- E W Meynell
G.C. Meynell, E.W. Meynell, Theory And Practice in Experi-mental Bacteriology, second ed., Cambridge University Press, London, 1965.
Effect of algalization on soil properties and yield of IR8 rice variety
- R S Aiyer
- V O Aboobekar
- G S Venkataraman
- S K Goyal
R.S. Aiyer, V.O. Aboobekar, G.S. Venkataraman, S.K. Goyal,
Effect of algalization on soil properties and yield of IR8 rice
variety, Phykos 10 (1971) 34e39.
Algal Biofertilizers and Rice Cultivation, Today and Tomorrow Printers and Publishers
- G S Venkataraman
G.S. Venkataraman, Algal Biofertilizers and Rice Cultivation,
Today and Tomorrow Printers and Publishers, New Delhi,
1972, p. 75.
Algal inoculation of rice fields
- Venkataraman
G.S. Venkataraman, Algal inoculation of rice fields, in: Nitrogen and Rice, International Rice Research Institute, Los Banos,
Philippines, 1979, pp. 311e321.
Growth promoting substances of cyanobacteria. I. Vitamins and their influence on rice plant
- Misra
S. Misra, B.D. Kaushik, Growth promoting substances of
cyanobacteria. I. Vitamins and their influence on rice plant,
Proc. Indian Sci. Acad. B 55 (1989) 295e300.
Effect of inoculation of alga Tolypothrix tenuis on the yield of rice and soil nitrogen balance
- A N Ibrahim
- M Kamel
- M El-Sherbeny
A.N. Ibrahim, M. Kamel, M. El-Sherbeny, Effect of inoculation
of alga Tolypothrix tenuis on the yield of rice and soil nitrogen
balance, Agrokem. Talajtan 20 (1971) 389e400.
Amelioration of salt affected soils with blue green algae. II. Improvement in soil properties
- Kaushik
B.D. Kaushik, D. Subhashini, Amelioration of salt affected soils
with blue green algae. II. Improvement in soil properties, Proc.
Indian Sci. Acad. 51 (1985) 386e389.
Work Done on Blue Green Algae in Relation to Agriculture, Indian Council of Agricultural Research
- A Sankaram
A. Sankaram, Work Done on Blue Green Algae in Relation to
Agriculture, Indian Council of Agricultural Research, New
Delhi, 1971, p. 28.
Nitrogen fixation in wetland rice fields Current Developments in Biological Nitrogen Fixation
- I Watanabe
- P A Roger
I. Watanabe, P.A. Roger, Nitrogen fixation in wetland rice fields, in: N.S. Subba Rao (Ed.), Current Developments in Biological Nitrogen Fixation, Oxford IBH, New Delhi, 1984, pp. 237e276.
Role of Blue Green Algae in Nitrogen Economy of Indian Agriculture, Indian Council of Agricultural Research
- R N Singh
R.N. Singh, Role of Blue Green Algae in Nitrogen Economy of
Indian Agriculture, Indian Council of Agricultural Research,
New Delhi, 1961, pp. 175.
A survey of soil cyanobacterial isolates forming associations with roots
A survey of soil cyanobacterial isolates forming associations
with roots, New Phytol. 118 (1991) 477e483.
Colonization of wheat (Triticum vulgare L.) by N 2 -fixing cyanobacteria. IV. Dark nitrogenase activity and effects of cyanobacteria on natural 15 N abundance on plants
- M Gantar
- N W Kerby
- P Rowell
- Z Obreht
- R Scrimgeour
M. Gantar, N.W. Kerby, P. Rowell, Z. Obreht, R. Scrimgeour,
Colonization of wheat (Triticum vulgare L.) by N 2 -fixing
cyanobacteria. IV. Dark nitrogenase activity and effects of
cyanobacteria on natural 15 N abundance on plants, New Phytol.
129 (1995) 337e343.
Characterization of cyanobacteria from the rhizosphere of wheat. M.Sc dissertation, Division of Microbiology, Post Graduate School
- N Karthikeyan
N. Karthikeyan, Characterization of cyanobacteria from the rhizosphere of wheat. M.Sc dissertation, Division of Microbiol-ogy, Post Graduate School, Indian Agricultural Research Institute, New Delhi, 2006.
Effect of inoculation of alga Tolypothrix tenuis on the yield of rice and soil nitrogen balance
- Ibrahim
Effect of algalization on soil properties and yield of IR8 rice variety
- Aiyer
Colonization of wheat (Triticum vulgare L.) by N2-fixing cyanobacteria. IV. Dark nitrogenase activity and effects of cyanobacteria on natural 15N abundance on plants
- Gantar