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A) Acid phosphatase activity in rhizosphere and bulk soils of Cyclopia genistoides; B) Acid phosphatase activity in rhizosphere soil of Cyclopia genistoides, Aspalathus caledonensis, Aspalathus aspalathoides and Leucadendron strictum sampled from Koksrivier farm. Data are mean for enzyme activity and error bars show one standard error; columns with different letters are significantly different at P ≤ 0.05.
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Abstract: The Cape fynbos is characterised by highly leached, sandy, acidic soils with very low nutrient concentrations.
Plant-available P levels range from 0.4 μg P g-1 to 3.7 μg P g-1 soil, and 1-2 mg N g-1 soil. Despite these low nutrient concentrations,
the fynbos is home to 9,030 vascular plant species with 68.7% endemicity. How native plant s...
Contexts in source publication
Context 1
... soil therefore usually has higher phosphatase activity than bulk soil (Fig. 1A). Three fynbos legumes, (namely Cyclopia genistoides, Aspalathus caledonensis, Aspalathus aspalathoides and the non-legume Leucadendron strictum) co-occurring at the same fynbos site showed significant variation in acid phosphatase activity. The Cyclopia species exhibited significantly higher APase activity in its rhizosphere, followed ...
Context 2
... and the non-legume Leucadendron strictum) co-occurring at the same fynbos site showed significant variation in acid phosphatase activity. The Cyclopia species exhibited significantly higher APase activity in its rhizosphere, followed by A. caledonensis, Aspalathus aspalathoides and L. strictum, which recorded a much lower APase activity (Fig. 1B). This might suggest that these legumes exhibit different degrees of tolerance to low P in the Cape fynbos. No doubt, the synthesis of macromolecules such as enzymes is very costly to the C economy of plants, hence their formation in large quantities can only occur when there is a strong biological demand, such as enhancing P ...
Context 3
... different degrees of tolerance to low P in the Cape fynbos. No doubt, the synthesis of macromolecules such as enzymes is very costly to the C economy of plants, hence their formation in large quantities can only occur when there is a strong biological demand, such as enhancing P acquisition in low-P environments [8,25]. However, the data in Fig. 1B could also be interpreted to mean that A. aspalathoides and L. strictum probably have other mechanisms for increasing P availability in the rhizosphere for plant uptake. Interestingly, excavation of these plants at Koksrivier frequently revealed the presence of a large mass of cluster roots on A. aspalathoides and ...
Citations
... Phosphatase are involved in phosphorus cycling (García-Ruiz et al. 2008) and they also respond rapidly to environmental factors such as temperature, moisture, and pH and soil alterations (García-Ruiz et al. 2008;Adetunji et al. 2020). Furthermore, the changes in phosphatase activities after organic and nitrogen fertiliser applications have been reported under different cropping systems (Maseko and Dakora 2013;Kobierski et al. 2020). showed that soil depth did not affect phosphatase activity in any of the soils after irrigation with diluted WWW. ...
Climate change, water scarcity, and soil degradation are among the key
factors affecting agricultural productivity. This has led to an increase in the demand
for irrigation water in farming systems. There is a growing interest in the use of
winery wastewater (WWW) as an optional source of clean water for irrigation in the
cropping systems, especially in vineyards. Irrigation with WWW promotes soil
fertility by increasing organic carbon, nitrogen, phosphorus, potassium, and sodium
levels in the soil. Since WWW contains high concentrations of sodium and potassium, the long term and/or unregulated use in agricultural fields may result in soil salinity or sodicity which can negatively affect bioavailability of nutrient elements and crop performance. However, the implication of WWW use for soil quality/health properties has not been widely discussed. Thus, this chapter reviews the impact of WWW irrigation on soil physical, chemical, and biological properties, as well as crop productivity and environmental health.
... Phosphatase are involved in phosphorus cycling (García-Ruiz et al. 2008) and they also respond rapidly to environmental factors such as temperature, moisture, and pH and soil alterations (García-Ruiz et al. 2008;Adetunji et al. 2020). Furthermore, the changes in phosphatase activities after organic and nitrogen fertiliser applications have been reported under different cropping systems (Maseko and Dakora 2013;Kobierski et al. 2020). Mulidzi et al. (2016) showed that soil depth did not affect phosphatase activity in any of the soils after irrigation with diluted WWW. ...
... An interesting family to further consider is Fabaceae, because at least some species in the large Daviesia group (Mirbelioids) in this family in Australia produce cluster roots (Nge et al. 2020b) and at least one of these species functions at mature leaf [P] similar to Banksia and Hakea . Likewise, in fynbos, Aspalathus and Cyclopia species (Fabaceae) produce cluster roots (Maseko and Dakora 2013;Allsop and Stock 1993;Power et al. 2010). In the same family, Lupinus species in the Mediterranean and the Americas are non-mycorrhizal, and some produce cluster roots or release carboxylates without these specialised structures (Lambers et al. 2013). ...
Background and aimsPlant species richness increases with declining soil phosphorus (P) availability, especially for Proteaceae in old infertile landscapes. This difference in richness might be attributed to faster diversification in lineages adapted to P-impoverished soils, i.e. species that possess specialised P-acquisition strategies, and have lower leaf P concentration ([P]) and higher seed [P]. Alternatively, a longer time for species accumulation might contribute to high species richness in low-P environments due to the geological stability of the landscapes in which they evolved.Methods
We assessed differences in diversification of Proteaceae in P-impoverished vs. nutrient-rich environments and whether these were linked to adaptations to P-impoverished soils. We explored mature leaf and seed [P] and investigated how these traits changed over the evolutionary history of the family, and within two species-rich genera (Banksia, Hakea).ResultsFaster diversification was correlated with lower leaf and higher seed [P] for species-rich genera across the Proteaceae. For Banksia and Hakea, diversification rates peaked at relatively low leaf [P], but not at the lowest leaf [P]. Ancestral state reconstructions indicated that low leaf [P] is a trait that was likely present in the early evolution of the Proteaceae, with recent transitions to higher leaf [P] across several species-poor rainforest genera.Conclusions
Diversification of Proteaceae correlated strongly with P-related traits. In an evolutionary context, functional cluster roots, low leaf [P] and high seed [P] were likely key innovations allowing diversification. Selection for low leaf [P] early in the evolutionary history of Proteaceae pre-adapted ancestors of this family to diversify into oligotrophic environments. We discuss how our findings are likely relevant for understanding diversification dynamics of other plant families that occur in P-impoverished environments.
... Symbiotic interactions between plants and soil bacteria may play a critical role in the survival of A. linearis. Moreover, bacteria are essential in soil nutrient cycling processes and also enhance plant productivity through N fixation, nutrient acquisition, and the production of various growth factors (Cloete et al., 2007;Masson-Boivin et al., 2009;Doornbos et al., 2012;Maseko and Dakora, 2013). ...
Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea. Symbiotic interactions between A. linearis and soil bacteria play an important role in the survival of Aspalathus plants in the highly nutrient-poor, acidic fynbos soil. The aim of this study was to characterize and compare rhizosphere and bulk soil bacterial communities associated with natural and commercially grown A. linearis, as well as the effect of seasonal changes on these communities. Bacterial communities were characterized using high throughput amplicon sequencing, and their correlations with soil chemical properties were investigated. The N-fixing bacterial community was characterized using terminal restriction fragment length polymorphism and real time quantitative polymerase chain reaction. Actinobacteria, Proteobacteria, and Acidobacteria were the most dominant bacterial phyla detected in this study. Highly similar bacterial communities were associated with natural and commercially grown plants. Significant differences in the bacterial community were observed between rhizosphere and bulk soils collected in the dry season, while no significant differences were detected in the wet season. This study provides insights into bacterial community structure and potential factors shaping bacterial community structure with commercially important A. linearis.
... A complex ecosystem of bacteria, fungi, protists and animals inhabits the soil [27], and mostly exhibit positive ecological interactions that promote plant growth. In order to make nutrients such as nitrogen and phosphorus, available to plants, both plants and microorganisms excrete enzymes to cleave nitrogen and phosphorus from organic forms [28,29]. Nitrogen limitations of soils are also overcome by the fixing of atmospheric nitrogen by various bacterial taxa associated with leguminous plants, as well as a number of free-living bacteria [30]. ...
... Microorganisms in the rhizosphere react with multiple metabolites released by plant roots, where they have mutualistic relationships that favor plant growth, change nutrient dynamics, and also alter the plants vulnerability to heavy metals, abiotic stress, and diseases [32]. In return, plants release compounds in the form of root exudates, creating a unique environment in the rhizosphere and providing microbes with essential components such as sugars, amino acids, flavonoids, aliphatic acids, proteins and fatty acids [28,33]. In some cases, plants can also use their exudates to suppress the growth of microorganisms to reduce the competition for nutrients in low concentrations [31]. ...
The Cape Floristic Region (CFR) is globally known for its plant biodiversity, and its flora is commonly referred to as fynbos. At the same time, this area is under severe pressure from urbanization, agricultural expansion and the threat of invasive alien plants. Acacia, Eucalyptus and Pinus are the common invasive alien plants found across the biome and considerable time, effort and resources are put into the removal of invasive alien plants and the rehabilitation of native vegetation. Several studies have shown that invasion not only affects the composition of plant species, but also has a profound effect on the soil chemistry and microbial populations. Over the last few years, a number of studies have shown that the microbial populations of the CFR are unique to the area, and harbour many endemic species. The extent of the role they play in the invasion process is, however, still unclear. This review aims to provide an insight into the current knowledge on the different microbial populations from this system, and speculate what their role might be during invasion. More importantly, it places a spotlight on the lack of information about this process.
... A similar trend was also observed in the results of this study, in which there was a lower acid phosphatase activity in amaranth relative to cowpea (Table 2; Figure 3). In other studies, for example, elevations in arbuscular mycorrhizal fungi spores in a non-legume crops such as maize [42], cluster roots in L. strictum [43] and higher organic matter [44] prompted the phosphatase activity. In the case of this study, for amaranth to be able to have enzymatic activity, root hairs may have played a key role. ...
Low available soil phosphorus (P) is associated with its immobility, which renders it unavailable for plant uptake. In addition, farmers normally apply inorganic fertilisers to legumes to activate soil-bound phosphorus using root exudates. Sufficient soil mineral nutrition is key to sustainable crop production, and hence food and nutritional security. The aim of this study was to quantify the acid and alkaline phosphatase activity as an indicator of P supply and availability under varying levels of nitrogen, phosphorus and potassium (NPK) fertilization and different cropping systems. An intercropping (cowpea and amaranth) and fertiliser (control, 25%, 50%, and 100% of the recommended NPK levels) field trial was laid out in a 2 × 4 factorial treatment structure in a completely randomized design (CRD) with four replications. There was higher acid and alkaline phosphatase activity in the rhizosphere of cowpea and amaranth grown as sole crops compared to those from intercropping. The cowpea and amaranth plants grown without fertiliser or 25% NPK had the highest rhizospheric phosphatase activity, while 100% NPK application exhibited the least. The markedly higher phosphatase activity from the low fertiliser application treatments indicates the possible stimulation of microbial activity to supplement P demands for the crops. The study revealed that the application of lower rates inorganic fertilisers in a legume intercrop stimulates the activity of the phosphatase enzymes, which can subsequently liberate soil-bound phosphorus. Plant tissue phosphorus concentration of cowpea and amaranth plants increased proportionately to the increase in fertiliser application up to 50% of the recommended NPK level. The land equivalent ratio (LER) was greater than 1, indicating that it is more beneficial to intercrop cowpea and amaranth as opposed to growing them as sole crops. Overall, the application of NPK fertilizer to amounts of up to 50%, based on the results of this study, appear to be better than 100% in terms of biomass accumulation and phosphate activity.
... A. linearis grows in sandstone derived soils that are well drained, nutrient poor and highly acidic (pH 3-5.3) (Muofhe and Dakora, 1999). Although these acidic soils are generally poor in biologically available P, the levels of P can be quite variable in the micro-molar range or even lower (Maseko and Dakora, 2013). Moreover, it is well-established that Fynbos plants are able to experience P-stress under extremely low P supply (Magadlela et al., 2016). ...
Phosphorus (P) is an essential mineral, required for crucial plant genetic, metabolic and signaling functions. Under P deficiency, normal physiological function can be disrupted, especially photosynthetic metabolism. The majority of photosynthetic studies of P stress has been on model organisms, and very little is known about plants that evolved on P deficient soils. Aspalathus linearis (Burm.f.) R.Dahlgren, a native to the Mediterranean ecosystem of South Africa was used to study the photosynthetic responses during short-term P limitation. A. linearis seedlings were cultured under glasshouse conditions and exposed to short-term P stress. Leaf photosynthetic gas exchange was coupled with metabolic analyses. In spite of the decline in leaf cellular Pi, the photosynthetic rates remained unchanged. These leaves also maintained their levels of light harvesting and reaction center pigments. The efficiency of the light reactions' utilization of ATP and NADPH increased during P-stress. Leaf glucose levels decreased during P-stress, while sucrose concentrations remained unaffected. These results show that during short-term P-stress, A. linearis can maintain its photosynthetic rates by altering the structural and functional components of the light reactions.
... V. divaricata (Adamson) like other temperate legumes is an amide exporting indigenous tree legume (Magadlela et al., 2017), growing in nutrient rich soils of forest-margins, but is reported to invade the mature fynbos (Coetsee and Wigley, 2013) The mature fynbos is characterised by soils that are acidic, highly leached and nutrient-poor, specifically in regards to phosphorus (P) (Coetsee and Wigley, 2013;Maseko and Dakora, 2013). Even though the fynbos vegetation has evolved with regular fires, the, post-fire alterations in the dynamics of soil nutrient availability, have been proposed as major factors in limiting the growth of legumes in mature fynbos (Manders et al., 1992;Coetsee and Wigley, 2013). ...
... In acidic soil conditions, the P ions can readily precipitate with cations (Dakora and Phillips, 2002), but may bind to organic compounds via microbial action Uhde-Stone et al., 2003). Therefore P concentration in fynbos soils, is generally available in micromolar or lower concentrations, and these P concentrations are extremely low to drive the P requiring metabolic processes, including N assimilation and metabolism (Maseko and Dakora, 2013). As such, low P availability is a critical limitation for plants, especially fynbos legume plants, as P is essential during N 2 fixation, N assimilation and metabolism during plant growth (Maseko and Dakora, 2013;Sulieman et al., 2013). ...
... Therefore P concentration in fynbos soils, is generally available in micromolar or lower concentrations, and these P concentrations are extremely low to drive the P requiring metabolic processes, including N assimilation and metabolism (Maseko and Dakora, 2013). As such, low P availability is a critical limitation for plants, especially fynbos legume plants, as P is essential during N 2 fixation, N assimilation and metabolism during plant growth (Maseko and Dakora, 2013;Sulieman et al., 2013). P deficiency affects N nutrition consequently the C costs of plants during growth (Magadlela et al., 2014). ...
... Previous studies have shown that plant roots exude many organic compounds, including organic acids, amino acids, proteins, phenolics and secondary metabolites (Erb et al., 2013;Huang et al., 2014). Among the many organic substances, organic acids are closely related to the availability of soil nutrients (Maseko and Dakora, 2013;Rengel, 2015;Dotaniya and Meena, 2015). To the best of our knowledge, many studies have primarily demonstrated that plants could activate P, Fe, Mo and Zn in soils by root exudates (Maqsood et al., 2011;López-Millán et al., 2012;Zhao and Wu, 2014), but little attention has been paid to the relationship between soil Se availability and organic acid secretion. ...
The aim of this research was to investigate the mechanism of selenium (Se) utilization by roots between two rice genotypes. The plant Se concentration, root organic acids secretion, soil Se fractions, soil pH, and infrared spectrum of soil were all determined through a root box experiment to clarify the differences in Se availability of rhizosphere soils between high- and low-Se rice cultivars. The results revealed that the grain Se concentration of the high-Se cultivar was significantly higher than that of the low-Se cultivar. The concentration of available Se, e.g. water-soluble and exchangeable, in the rhizosphere soil of the high-Se rice cultivar was dramatically higher than that of the low-Se rice cultivar, and the opposite result was observed in non-rhizosphere soil. The organic acids secretion of the high-Se rice cultivar showed a greater degree of reduction than that of the low-Se rice cultivar in response to the increase of Se application rates, while the infrared spectrum intensity of clay mineral in the rhizosphere of the high-Se rice cultivar exhibited a greater degree of increase than that of the low-Se rice cultivar. In addition, the pH of the rhizosphere soil of the high-Se rice cultivar was significantly higher than that of the low-Se rice cultivar at 0 mg kg ⁻¹ Se treatment. The results demonstrated that the high-Se rice cultivar could obtain more Se than the low-Se rice cultivar by mass flow, which is limited by the concentration of mobile Se in soil; The high-Se rice cultivar had a greater ability to activate Se by increasing soil pH than the low-Se rice cultivar; The secretion of organic acids could activate Se by degrading clay minerals, while the high-Se rice cultivar may have a greater ability to regulate the secretion of organic acids. The present study suggests the high-Se rice cultivar has stronger ability to increase Se availability of rhizosphere soil than the low-Se rice cultivar.
... The presence of legumes in any ecosystem, including savannahs, is determined among other factors by (i) the energetic requirements of N fixation, (ii) the limitations imposed by other nutrients such as phosphorus and (iii) the ecological factors that include competition, grazing and fire [6,7]. Phosphorus (P) is the second most important nutrient after N and it is a criticallimiting factor in legume plants as P deficiency affects both nodule formation and functioning [8,9]. Nodule formation and functioning is affected by P deficiency through the reduction in the amount of energy available, thereby reducing metabolic rates and the enzyme nitrogenase activity [10]. ...
The legume plant Vachellia sieberiana fixes atmospheric nitrogen (N) and distributes it back into ecosystems. We hypothesize that biological nitrogen fixation in this plant species, is limited by competition from the invasive shrub, Chromolaena odorata. Competition would therefore result in the legume plant switching its limited nitrogen (N) sources in phosphorus-poor soils in savannah ecosystems when resources have to be shared . This study investigated the different patterns of N use and growth costs by a native and an introduced leguminous shrubby species. We propose that the two species sharing the same environment might result in competition. The competitive effect would induce in the indigenous legume to better utilize atmospheric derived N rather than soil N that would modify plant growth kinetics and plant mineral concentrations. Seedlings of V. sieberiana, were cultivated in natural soil inoculum with low levels of phosphorus (mg.L-1±SE) of 3.67±0.88. The experiments were divided into two treatments where (i) seedlings of V. sieberiana were subjected to competition by cultivating them together with seedlings of C. odorata, and (ii) seedlings of V. sieberiana were cultivated independently. Although V. sieberiana was subjected to competition, the N2 fixing bacteria that occupied the nodules was Mesorhizobium species, similar to plants not subjected to competition. Total plant biomass was similar between treatments although V. sieberiana plants subjected to competition accumulated more below ground biomass and showed higher carbon construction costs than plants growing individually. Total plant phosphorus and nitrogen decreased in seedlings of V. sieberiana under competition, whereas no differences were observed in percent N derived from the atmosphere (%NDFA) between treatments. The specific nitrogen utilisation rate (SNUR) was higher in V. sieberiana plants subjected to competition while specific nitrogen absorption rates (SNAR) showed the opposite response.
V. sieberiana is highly adapted to nutrient-poor savanna ecosystems and can withstand competition from invasive shrubs by increasing below ground biomass and utilising both atmospheric and soil nitrogen sources.
