Investigating the effects of two cowpea (Vignaunguiculata L Walp) leaf harvesting intervals on grain yield

Abstract

Cowpea (Vigna Unguiculata L ) has a variety of uses in Zimbabwe. The crop can be used as food, leaves as vegetable for human and stems as fodder for livestock. Maximising both leaf, grain and the above ground biomass yield of the dual purpose cowpea is one of the ways to improve food security in the country as well as nutritious hay in winter for livestock thus ensuring sustainability in agriculture which is being threatened by climate change. A research was carried out to find out the effects of three leaf harvesting intervals on the dual purpose use of cowpea.The trial was carried out at Drawcard Farm, Harare, Zimbabwe on plots of 6m2gross and 2.6m2 net. The plots were laid down in RCBD with three treatments (no harvesting, 7-days and 14-days leaf harvesting intervals) replicated three times. The cowpea variety used was CBC2. Data collection was carried out two weeks after crop emergence (three leaf stage) up to six weeks (early reproductive stage). Overall, the results showed that leaf yield was higher in 7-day than 14-day interval. However grain and above ground biomass yields were highest (400.1kg/ha and 907.4kg/ha respectively) in control treatments followed by 14-day (101.3kg/ha and 696.1kg/ha respectively) and lastly 7-day (79.1kg/ha and 598.5kg/ha respectively) harvesting intervals. The conclusion drawn from the trial is that 7-day leaf harvesting interval increases cowpea leaf yield and 14-day interval increases grain and above ground biomass yield.