Effect of Drought Stress on Canopy Temperature, Growth and Yield Performance of Cowpea Varieties

Aim: To evaluate the influence of drought stress on canopy temperature, growth and yield performance of cowpea.

Study Design: The experiments were laid out in a split plot design, with main plots arranged into three replications as a randomized complete blocks design. Water stress level was assigned to the main plot while the cowpea variety was assigned to the subplot.

Place and Duration of Study: Study was carried out at Pwani University research farm in July – October 2011/2012 cropping season.

Methodology: The treatments comprised three water stress levels (no water stress, water stress at vegetative stage and water stress at flowering stage) and 11 cowpea varieties: KVU 419, Khaki, K80, Macho, Kaima koko, Nyeupe, KVU 27-1, Nyekundu, M66, Kutambaa and Mwandato. The data collected included: Ground cover, canopy temperature, chlorophyll content, leaf number, days to anthesis, shoot dry matter at maturity, pods per plant, grains per pod, 100-grain weight and grain yield.

Results: Water stress imposed at vegetative growth stage and flowering reduced cowpea growth attributes, ground cover and chlorophyll content, but increased canopy temperature, time to anthesis, harvest index, grain yield and yield components for most varieties. Water stress at vegetative and flowering stages increased time to anthesis by 4 and 7 days, respectively.

Conclusion: The impact of water stress on growth is dependent on the cowpea variety. Moderate stress may be beneficial if cowpea is grown for grain production but not if grown for vegetable production. Cowpea varieties which were superior in yield and high harvest indices under water stress included Nyekundu, KVU 27-1, M66, and KVU 419.