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Nutritional status of soils from KwaZulu-Natal modulate symbiotic interactions and plant performance in Vigna unguiculata L. (Walp)

Sithole, Nonkululeko, Pérez-Fernández, María, Magadlela, Anathi
Applied soil ecology 2019 v.142 pp. 1-7
Bacillus (bacteria), Rhizobium, Vigna unguiculata, carbon, ecosystems, grasslands, mycorrhizal fungi, nitrogen, nutrient requirements, nutritional status, nutritive value, phytomass, root nodules, savannas, seeds, semiarid zones, soil, soil bacteria, vesicular arbuscular mycorrhizae, South Africa
Vigna unguiculata L. (Walp) has high nutritional value. It thrives in semi-arid regions with low nutrient requirements thanks to the establishment of efficient symbiosis with soil borne bacteria. We investigated legume-plant-microbe symbiosis, nitrogen nutrition and associated C construction costs of V. unguiculata grown in nutrient-poor soils from savannah and grassland ecosystems. V. unguiculata seeds were germinated and grown in natural soils from the KwaZulu-Natal (KZN) province. Studied soils showed significant differences in soil nutrition status and microbial diversity. A combination of Rhizobium sp. and Bacillus sp. strains were isolated from root nodules together with arbuscular mycorrhizal (AM) fungi. V. unguiculata efficiently fixed 53–79% of their total plant N from the atmosphere and proved to rely on soil available N. Hluhluwe and Izingolweni soil grown V. unguiculata increased plant biomass compared to other soils. Carbon (C) construction costs were significantly higher in V. unguiculata grown in Bergville and Ashburton soils, whereas no differences in total N and P contents were observed among soils. For the first time we have proven that V. unguiculata may adapt to nutrient-poor soils by establishing multiple symbiosis with soil microorganisms and shifting N source preference.