The rising costs of oil, geopolitics, and frequent climatic events contribute to the scarcity and rising cost of inorganic fertilisers which leads to their unaffordability by poor-resourced farmers. There is a need to assess alternative inputs that are accessible, affordable and sustainable. Such alternative includes the application of biofertilizers as they are biological remedies that have been proven to promote sustainable production, especially food legume crops. In this study, we assessed whether co-inoculation of cowpea with Bradyrhizobium japonicum and Bacillus subtilis (strain BD233) could alter its growth and physiological performance when grown in a naturally lit glasshouse. The experiment was carried out in a completely randomized design (CRD) with four treatments replicates 12 times. The treatments entailed Bradyrhizobium japonicum and Bacillus subtilis (strain BD233), single inoculation of Bradyrhizobium japonicum, 0.5 mM NO3 as positive control (N source) and uninoculated (untreated). Chlorophyll content and stomatal conductance were determined at the mid-flowering growth stage and yield, biomass and nodulation were determined during the maturity growth stage. Our results showed that when dual inoculation of nitrogen fixing rhizobia and plant growth promoting rhizobacteria resulted in enhanced root fresh and dry weight, nodule number and nodule fresh, number of pods, number of seeds, chlorophyll content, stomatal conductance, and concentration of metabolites. The findings from the study support several of the United Nations Sustainable Development Goals (SDGs) including SDG 2, SGD 12 and SDG 13 which focuses on food and nutrition security, sustainable use of inputs and the resilience of the climate by minimising the need to use synthetic fertilisers. Clearly, dual inoculation of cowpea seeds using the selected bio-inputs is important as a sustainable agronomic approach to enhance growth performance and metabolites contributing to the cost-effective cowpea production.
Nelwamondo et al. (Mon,) studied this question.