Farm management has a greater impact on common bean rhizobia diversity and abundance than rainfed treatment

Abstract

Drought is one of the biggest problems for crop production and affects the survival and persistence of soil rhizobia. The reduced presence of rhizobia limits the establishment of symbiosis and endangers the productivity of legumes, which is the main source of plant protein worldwide. Thus, the preservation of soil microbial diversity increases the likelihood of stress-tolerant rhizobia and the potential for effective symbiotic relationships, improving crop resilience to stresses. Aim Since the biodiversity can be affected by several factors including abiotic stresses or cultural practices, the objective of this research was to evaluate the effect of water availability, plant genotypes and agricultural management on the presence, nodulation capacity and genotypic diversity of rhizobia. Method A field experiment was conducted with twelve common bean genotypes under irrigation and rain-fed conditions, bothin conventional and organic management. Estimation of the number of viable rhizobia present in soils was performed before the crop establishment, whereas the crop yield, nodule number and the strain diversity of bacteria present in nodules were determined at postharvest. Results Drought reduced the number of nodules and of isolated bacteria and their genetic diversity, although to a lesser extent than the agrochemical inputs related to conventional management. In addition, the crop yield showed positive correlation with the number of nodules and the diversity of isolated strains. Conclusions The maintenance of diversity will be a key factor to maintain crop production in the future, as problems caused by drought will be exacerbated by climate change.