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N and C nutrition, and δ 13 C of Cyclopia subternata plants of different ages sampled from Kanetberg (n = 10)
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Aims
Cyclopia and Aspalathus are legumes harvested for production of Honeybush and Rooibos tea, respectively. Farmers grow these species from either seeds or cuttings over several years with continuous annual harvesting. The aims of this study were to assess the effect of plant age, plant species, toposequence, planting material and farmer practice...
Contexts in source publication
Context 1
... analysis of C. subternata plants aged 8, 7, 6, 5, 4, and 2 years at Kanetberg revealed significant differences in sym- biotic parameters. Although N concentrations were similar for C. subternata plants of all ages (except those aged 6 years), the δ 15 N values were lowest for 4-and 7-year old plants, and highest for 8, 5 and 2-year old plants (Table 5). As a result, the %Ndfa was much greater for plants aged 4 years, and lowest for those that were 2 years old (Table 5). ...
Context 2
... N concentrations were similar for C. subternata plants of all ages (except those aged 6 years), the δ 15 N values were lowest for 4-and 7-year old plants, and highest for 8, 5 and 2-year old plants (Table 5). As a result, the %Ndfa was much greater for plants aged 4 years, and lowest for those that were 2 years old (Table 5). ...
Context 3
... δ 13 C was lowest in the youngest plants and much greater in their older counterparts. The C/N ratios were also lower in younger plants and in 6-year-old plants ( Table 5). ...
Context 4
... same could be said of A. caledonensis and A. aspalathoides, which showed greater water-use efficiency and therefore derived a higher proportion of their N nutrition from symbiosis than C. genistoides, which co-occurred in the same habitat and showed lower water-use efficiency and less N derived from symbiosis Table 4). The fact that the more water-use efficient legumes obtained the most N from atmospheric fixation was again confirmed for C. subternata plants aged 4 years ( Table 5). ...
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Citations
... In this study, dual inoculation of B. japonicum and B. subtilis increased C assimilation in drought stressed Bambara groundnuts shoots. Maseko and Dakora [34] indicated that carbon assimilation in plants represents a direct measure of photosynthetic activity. A reduction in the rate of photosynthesis could be an adaptation mechanism adopted by plants to mitigate the effect of drought. ...
... The three-way ANOVA demonstrated in Table 2 revealed significant differences between landraces and across inoculations under varying drought stress levels (*p ≤ 0.05, **p ≤ 0.01) on the C/N ratio of Bambara groundnut. The C/N ratio is generally regarded as a good indicator of the N status of plants because the plant N nutrition regulates the photosynthetic C accumulation [34]. Hobbie [36] differentiated symbiotic legumes from non-legumes by describing symbiotic legumes as the plants that can exhibit C/N values of <24 g g − 1 , while non-legumes exhibit C/N ratios > 24 g g − 1 . ...
... N, or 1 to 2 mg N g À1 soil) and P (0.00004 to 0.00037% P, or 0.4À3.7 mg P g À1 ) (Cramer 2010), most fynbos legumes have adopted various strategies (Maseko and Dakora 2013;Richardson et al. 2009) for meeting their nutritional requirements which include N 2 fixation, mycorrhizal infection, cluster root formation and change in root architecture. Maseko and Dakora (2015) have reported high symbiotic N dependency as nutritional strategy by wild legumes in the Cape fynbos, especially species of the genus Cyclopia and Aspalathus. Kanu and Dakora (2012) have similarly found high dependency of Psoralea species on N fixation for their N nutrition in the low N soils of the Cape fynbos soil. ...
... Therefore, ecophysiological studies are important for conserving these plant species in the Cape fynbos. Notwithstanding that some work has been done on symbiotic N 2 fixation in Fynbos legumes (Maseko and Dakora 2015;Mpai et al. 2020), however little is known of the genus Aspalathus, which is the largest in the Fabaceae Family in the Cape fynbos. So far, however, only about 70 species of the Leguminosae family have been evaluated for their N nutrition from symbiotic fixation (Sprent 2009). ...
... These values are interesting because normally, the expected shoot C concentration in legumes should be about 30% as estimated by (Sprent et al. 1996). However, studies by (Mohale et al. 2014;Mapope and Dakora 2016;Maseko and Dakora 2016) reported greater shoot %C in various legumes. According to Post et al. (2007), shoot % C values of legumes that are above 30% and/or 35%, could be an indication of high lipid distribution within the plant organ. ...
Adding biochar to soil can alter soil properties and thus affect plant growth; however, the effect of biochar on biological nitrogen fixation, carbon accumulation and water-use efficiency of chickpea in tropical soils is not fully understood. Therefore, this study assessed the efficacy of biochar derived from poultry litter (denoted as PLB) and acacia (denoted as ACB) feedstocks on biological nitrogen fixation, carbon accumulation and water-use efficiency (δ¹³C) of chickpea grown in three contrasting soils of Fernwood (Arenosol) and Griffin (Helvic Acrisol) and Pinedene (Gleyic Acrisol). The biochars were applied at the rate of 0.5%, 1% and 2% (w/w) with control (0%) and replicated four times. Chickpeas grown in PLB treatments in Griffin and Pinedene soils investigated accumulated more N and C, for greater biomass production, resulting in an average total N-fixed of 77 and 52 mg N/plant, respectively. Nitrogen fixation and carbon accumulation of chickpea increased by the addition of 0.5% PLB and ACB in the Fernwood soil. The findings of this study demonstrate the potential of improving N inputs through biological nitrogen fixation with poultry litter biochar application in soils with varying nutrient status and texture, which is important in arid environments with limited N inputs.
... Several studies have investigated the dependence of selected native Cape fynbos species on Biological Nitrogen Fixation (BNF) under field and glasshouse conditions (Muofhe and Dakora 1999;Cocks and Stock 2001;Spriggs and Dakora 2009;Kanu and Dakora 2012;Magadlela et al. 2014;Maistry et al. 2015;Maseko and Dakora 2015). Furthermore, the N contribution by some regional endemic plant species has been assessed using the 15 N natural abundance technique. ...
... W. sericea obtained 90% of their N from symbiosis which was significantly higher, while W. obcordata and W. tetraptera, respectively, derived 84 and 79% of their N nutrition from BNF (Table 5). As found with Cyclopia species and Aspalathus linearis (Muofhe and Dakora 1999;Maseko and Dakora 2015), there was an age effect on the symbiotic performance of W. sessilifolia. Younger plants had much lower δ 15 N and hence higher %Ndfa values (Table 5). ...
... Younger plants had much lower δ 15 N and hence higher %Ndfa values (Table 5). This is in contrast to the reported higher N 2 fixation in older plants of Aspalathus linearis (Muofhe and Dakora 1999) and Cyclopia genistoides in fynbos region (Maseko and Dakora 2015). The differences, in the %Ndfa values between young and old ages of W. sessilifolia plants, may be due to a requirement of δ 15 N from the soil. ...
Species of the genera Polhillia, Wiborgia and Wiborgiella are endemic to the Cape fynbos, South Africa. These plants form root nodules with soil rhizobia that fix atmospheric nitrogen. Little is known about their N and P nutrition, as well as their water-use efficiency in this highly dry and nutrient-poor soil environment. Therefore, the aim of this study was to assess P nutrition and water-use efficiency in natural stands of Polhillia, Wiborgia and Wiborgiella species as well as their dependency on Biological N2 fixation for nutrition. The δ15N natural abundance technique was used to measure the symbiotic performance. The Acid and alkaline phosphatase activities were assayed using p-nitrophenol method. 16S rRNA sequence was used to identify microsymbionts nodulating the test plants. The δ15N study showed a high dependency of the tested species on N2 fixation. The N derived from fixation was 76–84% for Polhillia sps., 73–91% for Wiborgia sps., and 61–68% for Wiborgiella sessilifolia. The species differed in water-use efficiency, with δ13C values of −28.1 to −25.1‰ for Polhillia sps., −28.3 to −25.8 ‰ for Wiborgia sps., and − 27.7 to −27.1‰ for Wiborgiella sessilifolia. The rhizosphere acid and alkaline phosphatase activities were higher in P. brevicalyx and P. pollens, than in the other tested species and this resulted in greater available P in the rhizosphere soils and an increased P uptake and accumulation in the plant shoots. Based on 16S rRNA nucleotide sequence and phylogenetic analysis of root nodule isolates, a diverse and novel Mesorhizobium sps. nodulate the tested plant species in the fynbos ecosystem.
... Lower (more negative) δ 13 C signatures in leaf, bark and roots from Juglans in the mixed stand compared to the monoculture may therefore be an indicator of greater water availability. This was also found in previous studies with various legumes growing alongside non-N 2 -fixing species (Parrotta, 1999;Maseko and Dakora, 2015). ...
The Loess Plateau in northwestern China constitutes one of the most vulnerable semi-arid regions in the world due to long-term decline in forest cover, soil nutrient depletion by agricultural use, and attendant soil erosion. Here, we characterize the significance of N2-fixing Robinia pseudoacacia L. and non-N2-fixing Juglans regia L. for improving nutrient availability and water retention in soil by comparing a range of biological and physicochemical features in monoculture and mixed plantations of both species. We found that N2-fixing Robinia facilitates the nitrogen and phosphorus composition of non-N2-fixing Juglans in the mixed stand as a consequence of improved soil nutrient availability, evident as higher levels of nitrogen and labile carbon compared to mono-specific stands. This demonstrates that intercropping N2-fixing Robinia with non-N2-fixing woody plants can greatly improve soil carbon and nitrogen bioavailability as well as whole-plant nutrition and can potentially mediate water retention with additional sequestration of soil organic carbon in the range of 1 t C ha−1 year−1. Thus, intercropping N2-fixing woody species (e.g. Robinia pseudoacacia or Hippophae rhamnoides L.) with locally important non-N2-fixing tree and shrub species should be considered in afforestation strategies for landscape restoration.
The full article can be found here by the links:
https://authors.elsevier.com/c/1ZGDvB8cckQsz
... Ecologically speaking, legumes adapted to growth in nutrient-poor soils tend to underperform with mineral fertilization [e.g. Cyclopia longifolia (Vogel L.)] and usually prefer rhizobial symbiosis as N source and therefore fix more N 2 when nodulated by effective rhizobial strains (Muofhe and Dakora 1999;Maseko and Dakora 2015). Such legumes tend to perform poorly when grown with N and other mineral fertilizers (Ayisi et al. 2000;Mndzebele and Dakora 2017). ...
Although nitrate is known to inhibit nodulation and N2 fixation in symbiotic legumes, little is known about its effect on the uptake and accumulation of trace elements such as Fe, Zn, Mn and Cu. The aim of this study was to evaluate the effect of 5 mM NO3⁻ supply, either with or without rhizobial inoculation, on nodulation, nodule functioning and micronutrient levels in the shoots of soybean (Glycine max L.Merr.), Bambara groundnut (Vigna subterranea L. Vedc) and Kersting’s groundnut (Macrotyloma geocarpum Harm). The results showed reduction in plant growth, nodule formation and nodule dry matter by the supply of 5 mM NO3⁻ to inoculated seedlings of all three species. Nitrate inhibition respectively caused 1.2, 1.4, and 1.5-fold decrease in nodule number per plant in Bambara groundnut, soybean and Kersting’s bean, which resulted in 2.3, 3.3 and 4.5-fold reduction in nodule dry weight of the test species (in that order). The application of 5 mM NO3⁻ to soybean plants also resulted in 2.5, 4.0 and 5.4-fold decrease in shoot accumulation of Fe, Zn and Mn, respectively, when compared to the purely symbiotic control plants. Furthermore, we observed 1.3, 1.8 and 1.3-fold decreases in the concentration of Zn, Mn and Cu in shoots of inoculated Bambara groundnut with NO3⁻ supply, levels lower than those found in soybean. With Kersting’s groundnut, shoot concentration of Fe, Zn and Cu were higher with the application of 5 mM NO3⁻ to inoculated plants when compared to the purely symbiotic treatment, which was opposite to soybean. But pure NO3⁻feeding of this species respectively resulted in 2.0, 1.4 and 1.3-fold decreases in Fe, Zn and Cu relative to inoculated NO3⁻-fed plants. Clearly, NO3⁻ supply to landraces/genotypes of the three legume species did not only inhibit nodule formation and functioning, it also reduced shoot micronutrient levels in soybean and Bambara groundnut, but not Kersting’s bean.
... Some species had similar values in the managed plants and the natural sites, but there is variation of values at different sites ( Muofhe and Dakora, 1999;Spriggs and Dakora, 2009). Maseko and Dakora (2015) found that annual harvesting of the plants led to a decrease in N 2 fixation. Removal of the shoots affects the oxygen diffusion to the root nodules and leads to a decrease in nitrogenase activity ( Maseko and Dakora, 2015). ...
... Maseko and Dakora (2015) found that annual harvesting of the plants led to a decrease in N 2 fixation. Removal of the shoots affects the oxygen diffusion to the root nodules and leads to a decrease in nitrogenase activity ( Maseko and Dakora, 2015). ...
Aspalathus linearis (rooibos) and Cyclopia spp. (honeybush) are leguminous plants endemic to the fynbos region of South Africa. These plants have become popular for their use as herbal teas and thrive in the acidic, nutrient poor soils of the fynbos region. Plants in this region rely on rhizobia to fix nitrogen and supply them with other important nutrients such as phosphorous, in exchange for a carbon source. This review focuses on the species diversity of rhizobia associated with A. linearis and Cyclopia spp. plants. Genera that are regularly isolated from rooibos and honeybush root nodules include Rhizobium, Burkholderia, Mesorhizobium and Bradyrhizobium. These species produce bioactive compounds that directly or indirectly affect growth of leguminous plants.
... These processes also control the majority of nitrogen (N) and carbon (C) flows in the ecosystem via the degradation of litter and the mineralization of soil organic matter (Wu et al., 2010), N assimilation and C fixation by plants (Maseko and Dakora, 2015), and their consumption by animals with a partial return to the soil of these elements in the form of animal excreta (Schlecht et al., 2006). In pastoral ecosystems, livestock animals, particularly ruminants, play a major role in the organization of C&N cycles because they digest plants mainly composed of cellulose, with slow degradation (Petersen et al., 2013) and they produce faeces (urine and dung) with high N concentrations, providing the soil with C and N in available forms for microorganisms and plants (Whitmore, 2001). ...
This thesis aims to assess the impact of ruminant herds on the GHG balance of sylvo-pastoral ecosystems under semi-arid tropical climate. The study site is a circular area of 15 km radius centered on the Widou borehole (15°59’N, 15°19’W, 706 km²) representative of the sylvo-pastoral Ferlo Region in the Sahel belt of West Africa (North of Senegal). To achieve the GHG balance assessment, all GHG emissions related to ecosystem functioning (enteric fermentation from livestock and termites, microbial activity from soil and water, bush fire and borehole’s motor pump) and total carbon accumulation in the main sinks (soil organic matter, wood and root masses and livestock mass) were assessed at the monthly time scale and over the year cycle taking into account the spatial heterogeneity (6 landscape unit identified).
The main results of this thesis are:
• A strong spatial and temporal variability of GHG emissions from soil and surface water due to the deposition of livestock excretions , to biological activity of water and soil fauna and to root respiration. CO2 and N2O emissions from soil mainly relate to the excreta deposited while the CH4 emissions are strongly associated with the surface water and soil hydromorphic and anaerobic conditions. Stagnant water in the ponds and around the borehole are the main sources of CH4 in the study area due to the deposition of excreta by livestock in water when watering.
• A strong spatial heterogeneity of the greenhouse gas balance in relation to livestock activity. The landscape units that contribute more to the provision of forage to livestock (rangelands, forest plantations) have negative balances ranging between -0.08 and -0.92teq-C/ha/year. The landscape units that contribute less to livestock fodder provision and receive a large share of excreta deposition (pastoralist settlements, ponds and vicinity of borehole) have positive balances ranging between +0.01 and + 32.70teq-C/ha/year.
• A large seasonal variability of enteric methane emissions by livestock due to the regional mobility of the herds and the changing diets over time. In the context of a dry tropical climate with marked seasons in Sub-Saharan Africa the enteric CH4 emission of one Tropical livestock Unit over the year would be 27.9kgCH4/year, thus only 59% of the emission assessed by IPCC largely referred to in international literature.
• A large seasonal variability of GHG balance across the sylvo-pastoral landscape with a positive balance in the rainy season at + 0.18tC-eq/ha/month due to high GHG emissions caused by high soil moisture and to livestock excreta and vegetal organic matter deposited in the course of the preceding dry season. The GHG balance is negative during the cold dry season (-0.64teq-C/ha/year) and hot dry season (-0.13 teqC/ha/year) because some livestock area leaving the area in transhumance and because soil biological activity decreases as soil dry up.
• The GHG balance over the year and across the pastoral landscape is -0,02teq-C/ha/year setting the sylvo-pastoral ecosystem in an overall GHG equilibrium. Indeed GHG emissions would be offset by carbon storage over a year cycle.
This thesis highlights the benefits of an ecosystem approach of the GHG balance to better understand the drivers of the GHG balance and to suggest effective and appropriate mitigation options. Indeed this approach is built around the development of dynamic and spatialized visions of soil-plant-animal interactions in the ecosystem and the integration of these interaction effects within the GHG balance.
