Abstract:
Cowpea is grown in a wide range of environments, and drought is considered
as the single most devastating environmental stress, which decreases crop productivity more
than any other environmental stress. Lack of adequate soil moisture affects both the vegetative
and reproductive growth of legumes and leads to significant yield loss. Potassium fertilizer
mitigates the impact of water stress in plants. A study was conducted from July to September
2018 to investigate the effect of four rates of fertilizer potassium (MOP) including
recommended level (75Kg/ha), 125% of recommended level, 150% of recommended level,
175% of recommended level with two different soil moisture conditions as optimal and suboptimal
on growth of cowpea. These 8 treatments replicated three times in a Completely
Randomized Design (CRD) in a factorial manner. Growth parameters of cowpea were
recorded. The data were statistically analyzed using SAS and difference between treatment
means was compared using Duncan’s Multiple Range Test (DMRT). The tap root length of
cowpea showed a greater response to potassium fertilizer under suboptimal soil moisture.
Although differences were observed in the responses of the vegetative growth of cowpea to
moisture and potassium, in overall terms potassium promoted growth of cowpea when subject
to suboptimal soil moisture. Among all applications 175% of recommended potassium level of
cowpea proved to be the best to increase the shoot dry weight and leaf area at optimal
moisture conditions, and under sub-optimal moisture conditions it was the best to increase the
shoot dry weight and leaf area compared to recommended level of potassium in sandy regosol
soil. The results of this study suggested that the application of potassium fertilizer can be
considered as significant factor in overcoming soil moisture stress in cowpea.
