Impact of leaf harvesting on cowpea of the BEB type

In most communal areas of Zimbabwe farmers grow cowpea for vegetable leaves and grain. An evaluation of the impact of leaf harvesting intensity, frequency and duration on leaf and grain yield, nutritional composition and nodulation of Black-eyed bean (BEB) (determinate) compared to local landraces (indeterminate) was done on-farm in Mutoko District and University of Zimbabwe during the 2005/6 and 2006/7 rainy seasons. Leaf harvest intensity had three levels namely, one leaf, two leaves and three leaves per branch, while leaf harvest interval had two levels, weekly and fortnightly. An increase in leaf harvesting intensities significantly increased leaf yield and decreased grain yield. BEB produced higher grain and lower leaf yield in all the intensities, intervals and on both sites than the local landraces. BEB leaf and grain was largely nutritionally better than the local landrace. Nieto curves were exploited to determine the critical cowpea leaf harvesting periods. Leaf harvesting started at three leaf stages and only one leaf per branch was harvested per week. Pot experiment to investigate effects on nodulation was conducted in the 2006/7 rainy season in a glasshouse.