FIG 1 - uploaded by Marta Cristina Corsi de Filippi
Content may be subject to copyright.
Source publication
O mal-do-pé em arroz (Oryza sativa) foi constatado em lavouras de terras altas nos municípios de Unaí (MG), Palmeiras (GO), Itaberaí (GO), Humaitá (AM) e em lavouras irrigadas nos Estados de Goiás, Tocantins e Rio Grande de Sul. O agente causal foi identificado como Gaeumannomyces graminis var. graminis baseado em características morfológicas, cult...
Citations
... von Arx & D. Olivier var. graminis, was reported for the first time in some Brazilian states in the 1997/1998 growing season (Prabhu & Filippi, 2002). The disease can cause early grain maturation and reduce the number of grains per panicle and even the death of the tillers depending on the rice growth stage that fungal infection takes place (Ou, 1985;Peixoto, Ottoni, Filippi, Silva-Lobo, & Prabhu, 2013;Prabhu & Filippi, 2002). ...
... graminis, was reported for the first time in some Brazilian states in the 1997/1998 growing season (Prabhu & Filippi, 2002). The disease can cause early grain maturation and reduce the number of grains per panicle and even the death of the tillers depending on the rice growth stage that fungal infection takes place (Ou, 1985;Peixoto, Ottoni, Filippi, Silva-Lobo, & Prabhu, 2013;Prabhu & Filippi, 2002). ...
... Curiously, most of the information available in the literature regarding the biology of the genus Gaeumannomyces and the epidemiological aspects of the disease caused by this pathogen and its control is reported for wheat in contrast to rice (Prabhu & Filippi, 2002). ...
Crown sheath rot, caused by the ascomycete Gaeumannomyces graminis var. graminis that infects the root and the base of the culm of rice, causes early grains maturation, tiller death and reduced yield. As a paucity of information exists in the literature on the rice-G. graminis var. graminis interaction at the microscopic level, this study aimed to gain novel insights into the infection process of this pathogen in the root and culm of rice using both light and scanning electron microscopy. In the roots, the fungus initially colonized the epidermal, exodermal and sclerenchyma cells. At 15 days after inoculation (dai), fungal hyphae colonized the cortex and clusters of perithecia were observed in the roots. At 20 dai, the fungus reached the central cylinder, and an intense fungal colonization at the base of the culm was observed that resulted in the formation of a mycelial mat on both adaxial and abaxial surfaces of the leaf sheaths. At 25 dai, fungal growth was noticed in the parenchyma cells, vascular bundles and airspaces. Perithecia emerged through the base of prophyllum and from the first leaf sheath at 30 dai. The results of this study provide new insights into the infection process of G. graminis var. graminis in rice and may help to find better control measures in reducing crown sheath rot development.
... In phase III (1990 onward), the emphasis is on grain quality, yield potential, and blast resistance. The strong priority for blast resistance continues in the aerobic rice breeding program due to high incidence of blast in the savannah system (Prabhu et al., 1999;Prabhu and Filippi, 2002). Rice blast caused by fungus Pyricularia grisea is an important pathogen in rice grown on acid soils especially in dry years with heavy nitrogen fertilization . ...
... Evidence for soil-borne pathogenic fungus Gaemannomyceas graminis var. graminis in upland rice was reported from Brazil (Prabhu and Filippi, 2002). Similarly, Pythium aristsporum and other saprophytic fungi were considered the cause of failure in rice nursery, when the soil for the nursery was obtained from paddy fields (Furuya et al., 2003(Furuya et al., , 2005. ...
T
he increasing shortage of water resources
has led to the development and adoption
of aerobic rice system, which saves water
input and increases water productivity by
reducing water use during land preparation and
limiting seepage, percolation, and evaporation.
Aerobic rice also reduces labour requirement and
greenhouse gas emission from rice field. Aerobic
rice cultivars are adapted to aerobic soils and
have higher yield potential than traditional upland
cultivars. Grain yields of 5–6 t/ha can be achieved
in aerobic rice system
... Arx & D. Olivier var. graminis (anamorph: Gaeumannomyces hyphopodioides sp. with lobed hyphopodia), causing crown (black) sheath rot of rice was reported first in upland rice and subsequently spreaded to irrigated rice of North Eastern part of South America (Prabhu and Filippi 2002;Nunes 2008). The morphological features that discriminate the varieties are the lobed hyphopodia and the ascospore sizes (Mathre 1992). ...
Soil is of utmost important among the natural resources harbouring innumerable microbes essential for maintaining fertility, crop productivity vis-à-vis antagonism against pathogens. Phytopathogens are solely causative agent for wide range of crop diseases, resulting in decreasing crop productivity. The use of bioantagonist as biological control agents has been of great importance to combat phytopathogens rather using chemical pesticides. Biological control of crop pathogens comprises reduction of pathogen inoculum concentration or reduced infectivity. Using a specific bacterial species is an excellent and alternative option against rice pathogens as well as agrochemicals for a positive socio-ecological impact. The genus Bacillus offer several advantages over others in controlling rice pathogens through endospores and production of broad-spectrum antibiotics. The advances in molecular biology play a crucial role to find out the exact molecular pathways and mechanisms underlying antagonistic behaviour of Bacillus sp. facilitating disease remediation, improvement and wider use of biocontrol agents successfully. The pathways of biocontrol involve antibiosis, parasitism, cell wall degradation, competition for nutrients and space and induced disease resistance. The present chapter focuses on Bacillus sp. as a biocontrol agent against rice fungal pathogens including its mode of action, physiology, genetics, advantages, limitations and applications for diseases management.
... Os estudos de resistência realizados por Prabhu & Filippi (2002), utilizando doze genótipos de arroz irrigado e o isolado proveniente de arroz (Ggg-a 01), mostraram que todos os genótipos avaliados apresentaram reação de suscetibilidade. Não há informação, com relação ao grau de resistência de genótipos de arroz de terras altas a Ggg. ...
... Os demais genótipos foram considerados suscetíveis, com alturas de lesões intermediárias. Em estudos realizados por Prabhu & Filippi (2002), em 12 diferentes genótipos de arroz irrigado, utilizando-se o mesmo isolado e a mesma metodologia de inoculação, não foram observadas diferenças entre os genótipos. ...
Several gramineous plants occurring in rice fields show symptoms of crown sheath rot of rice, caused by Gaeumannomyces graminis var. graminis (Ggg), under natural conditions of infection. The pathogenicity of the Ggg-a 01 isolate, collected from rice, was tested on seven grass species and eight cereals, under greenhouse conditions, in order to get information on host-range and resistance of rice genotypes to crown sheath rot. The inoculation tests showed that the rice isolate was pathogenic to weeds such as Echinochloa crusgalli, Pennisetum setosum, Brachiaria sp., Digitaria horizontalis, Brachiaria plantaginea, Eleusine indica and Cenchrus echinatus, and that these species are potential hosts to the pathogen. Winter cereals such as wheat, oat, rye, barley and triticale, as well as sorghum, maize and millet, presented different degrees of susceptibility to the Ggg-a isolate. Significant differences were observed in relation to lesion height and production of hyphopodia and perithecia on culms. Perithecia were not observed on millet, sorghum, southern sandbur and maize. The resistance of 58 upland rice genotypes was tested, and the SCIA16 and SCIA08 genotypes presented lesion height significantly smaller, being considered resistant, when compared to the highly susceptible CNAS10351 genotype.
... von Arx & D. Olivier var. graminis, (Ggg) causing crown sheath rot of rice (Oryza sativa L.) was reported first in upland rice and later in irrigated rice in Brazil (Prabhu & Filippi, 2002;Nunes, 2008). Earlier reports refer to the synonyms Ophiobolus oryzinus and Ophiobolus graminis in Africa, Australia, India, Italy, Japan, Malaysia, New Guinea, North America, South America, Philippines, Sri Lanka and Sweden (Walker, 1981). ...
... The ascospores of Ggg can be actively released from the ascus in the atmosphere (Gregory & Stedman, 1958), but its role in the epidemics remains controversial (Gerlagh, 1968;Shipton, 1972). There is little information on the epidemiology of crown sheath rot of rice (Webster & Gunell, 1992) and only preliminary data on pathogenicity of Ggg in Brazil (Prabhu & Filippi, 2002). ...
A collection of Gaeumannomyces graminis var. graminis isolates obtained from symptomatic rice and grass plants in central and northern Brazil were studied in regard to pathogenicity on rice and cultural characteristics. For all isolates, only one type of lobed hyphopodia was observed both in the field and artificially inoculated plants. Perithecia were formed on artificial media and inoculated leaf sheaths. Hyphopodia were formed from ascosporic germ tubes. The hyphae under moist stress conditions produced dark brown chlamydospores that were initially hyaline. Large variation in the number of chlamydospores produced and duration of perithecia formation was observed among the isolates. Pathogenicity assays showed that 60-day old rice plants were more susceptible than 35-day old plants. The isolates from rice and grasses varied significantly in regard to disease severity on both rice seedlings and adult rice plants. In general, the isolates from rice were more aggressive than the isolates from grasses. Spontaneous infection of rice plants by ascosporic inoculum from perithecia on rice stubbles was observed in the greenhouse, suggesting their role as a source of primary inoculum in the field, which deserves further investigation.
... In phase III (1990 onward), the emphasis is on grain quality, yield potential, and blast resistance. The strong priority for blast resistance continues in the aerobic rice breeding program due to high incidence of blast in the savannah system (Prabhu et al., 1999;Prabhu and Filippi, 2002). Rice blast caused by fungus Pyricularia grisea is an important pathogen in rice grown on acid soils especially in dry years with heavy nitrogen fertilization . ...
... Evidence for soil-borne pathogenic fungus Gaemannomyceas graminis var. graminis in upland rice was reported from Brazil (Prabhu and Filippi, 2002). Similarly, Pythium aristsporum and other saprophytic fungi were considered the cause of failure in rice nursery, when the soil for the nursery was obtained from paddy fields (Furuya et al., 2003(Furuya et al., , 2005. ...
About 90% of rice is produced and consumed in Asia, where the demand for rice is on the increase due to increasing population. Rice is a semiaquatic plant and grows well under lowland flooded anaerobic conditions. Most high yielding varieties yielding 6–8t/ha have been developed to suit such conditions. However, there are large areas, where rice is grown under upland aerobic conditions with drought tolerant varieties that yield about 1t/ha or a little more. Aerobic rice varieties are now being developed that have drought tolerance as well as high yielding ability. Aerobic rice system (ARS) is a new production system in which rice is grown under nonpuddled, nonflooded, and nonsaturated soil conditions. The expected yields in ARS are somewhat lower than those obtained under lowland flooded conditions, but double or treble of that obtained under upland conditions. However, ARS has been successful in cool temperate regions. For warm humid rice growing regions, a partial aerobic rice system (PARS) may be a more plausible alternative. PARS technologies are available. Some available results, however, show a decline in rice yield over years in ARS and suggest that ARS may not be sustainable over a long period. The factors responsible appear to be N, P, K, Fe, and Zn deficiencies, weeds and soil-borne root-knot nematodes. Some of these problems can be overcome by introducing legume such as soybean in ARS/PARS. ARS/PARS call for application of herbicides and namaticides, which are going to add additional burden on poor Asian farmers. In addition, farmers have to be trained in the careful and proper use of herbicides and nematicides. Herbicides have also been associated with environmental pollution problems.
Transplanting after repeated puddling is the conventional method of rice (Oryza sativa) growing which is not only intensive water user but also cumbersome and laborious. Different problems like lowering water table, scarcity of labour during peak periods, deteriorating soil health demands some alternative establishment method to sustain productivity of rice as well as natural resources. Direct seeded rice (DSR), probably the oldest method of crop establishment, is gaining popularity because of its low-input demand. It offers certain advantages viz., it saves labour, requires less water, less drudgery, early crop maturity, low production cost, better soil physical conditions for following crops and less methane emission, provides better option to be the best fit in different cropping systems. Comparative yields in DSR can be obtained by adopting various cultural practices viz., selection of suitable cultivars, proper sowing time, optimum seed rate, proper weed and water management. It can also be stated that soil problems related to rice and following crops can be solved with direct seeding. There are several constraints associated with shift from PTR to DSR, such as high weed infestation, evolution of weedy rice, increase in soil borne pathogens (nematodes), nutrient disorders, poor crop establishment, lodging, incidence of blast, brown leaf spot etc. By overcoming these constraints DSR can prove to be a very promising, technically and economically feasible alternative to PTR.The potential benefits and constraints associated with adoption of DSR are discussed in this paper.
Rice is one of the most important food crops in the world, and staple for more than half of the global population. Looming water crisis, water-intensive nature of rice cultivation and escalating labour costs drive the search for alternative management methods to increase water productivity in rice cultivation. Direct seeded rice (DSR) has received much attention because of its low-input demand. It involves sowing pre-germinated seed into a puddled soil surface (wet seeding), standing water (water seeding) or dry seeding into a prepared seedbed (dry seeding). In Europe, Australia and the United States, DSR is highly mechanised. The development of early-maturing varieties and improved nutrient management techniques along with increased availability of chemical weed control methods has encouraged many farmers in the Philippines, Malaysia, Thailand and India to switch from transplanted to DSR culture. This shift should substantially reduce crop water requirements, soil organic-matter turnover, nutrient relations, carbon sequestering, weed biota and greenhouse-gas emissions. Still, weed infestation can cause large yield losses in DSR. In addition, recent incidences of blast disease, crop lodging, impaired kernel quality and stagnant yields across the years are major challenges in this regard. In this review, we discuss the experiences, potential advantages and problems associated with DSR, and suggest likely future patterns of changes in rice cultivation.Research highlights▶ Water crisis and escalating labour costs are threatening rice production. ▶·Because of its low-input demand, direct seeded rice is an attractive alternative. ▶·Early-maturing varieties, weed and nutrient management favour its adoption. ▶ Weeds, blast, lodging, poor kernel quality and low yields are the major challenges. ▶·Experiences, problems and opportunities of direct seeded rice have been discussed.
Aerobic rice is a new production system for water-short environments. Adapted varieties are usually direct dry seeded and the crop grown under aerobic soil conditions with supplementary irrigation as necessary. Occasionally, yield failures occur which may be related to soil health problems. In the dry season of 2006 and 2007, we conducted a field experiment in the Philippines, to identify the major causes of such yield failure. Four treatments were implemented: (i) Control of direct dry-seeded rice (improved upland variety Apo), (ii) Biocide application, (iii) transplanting into aerobic soil, and (iv) 1 year fallow. Yield in the Biocide treatment was 2 t ha−1 in both years. In all other treatments, yield was 0–0.3 t ha−1. Plants grown in the Biocide treatment showed a reduced degree of galling of roots caused by root-knot nematodes (RKN) and better general root health than the Control treatment. Potentially pathogenic fungi were isolated from root samples (Pythium sp., Fusarium sp., and a Rhizoctonia-like species). Abiotic effects of the Biocide treatment were an increase in KCl-extractable N (initial season 2007) and a decrease in initial soil pH. In the Control treatment, soil pH increased from 6.5 to 8.0 over the two seasons. In 2007, plant tissue analysis indicated Mn deficiency in the Control treatment. Plants that were subjected to foliar micronutrient sprays reacted positively to Fe and Mn sprays in the Control treatment, and Mn spray in the Biocide treatment. We concluded that the Biocide application led to favorable soil conditions by reducing biotic stresses such as RKN and improving nutrient availability. In the other treatments, an interaction of RKN and micronutrient deficiencies with increasing soil pH led to yield failure.
