Influence of soil moisture and fertilizer potassium on the vegetative growth of mungbean (Vigna radiata L. Wilczek) and cowpea (Vigna unguiculata L. Walp)

Tropical food legumes are grown in a wide range of environments, and water stress is considered the principal environmental Factor limiting growth and yield. Potassium fertilizer mitigates the impact of water stress in plants . However, the benefits of potassium in overcoming stress in tropical food legumes have not been investigated in comparative studies. Tile purpose of this study was to determine the benefits of potassium in overcoming water s tress in mungbean and cowpea, two important tropical food legumes with diff erent adaptabilities to Soil moisture regimes. The experiment carried out u nder controlled conditions placed emphasis on vegetative growth and selecte d physiological parameters. The impact of potassium was different in the tw o legumes grown at optimal and suboptimal soil moisture. Potassium increase d shoot growth of mungbean to a greater extent than in cowpea under subopti mal moisture conditions. The roots of cowpea showed a greater response to p otassium fertilizer than in mungbean under suboptimal soil moisture. The pl ant water relations and photosynthetic rates of mungbean were improved to a greater extent by potassium under suboptimal soil moisture than those of c owpea. Although differences were observed in the responses of the vegetativ e growth of these species to moisture and potassium, in overall terms potas sium promoted growth of both species when subject to suboptimal soil moistu re. While field studies are required to validate the results, the applicati on of potassium fertilizer can be considered a significant factor in overco ming soil moisture stress in these legumes commonly grown in tropical cropp ing systems.