Leaf Harvesting Time and Frequency Affect Vegetative and Grain Yield of Cowpea

Abstract

Cowpea [Vigna unguiculata (L.) Walp.] is a vital component of traditional cropping systems in the subtropics and tropics, grown both for high‐protein grain and nutritious fresh leaves. The objectives of this study were to determine the effects of (i) cropping regime and (ii) leaf harvesting initiation time and frequency on yield and yield components of dual‐purpose cowpea. Studies were conducted at the Kenya National Dry land Research Center–Katumani over four seasons. Cowpea cultivar ‘K80’ was grown as a monocrop or intercropped with maize. Leaf harvesting was initiated at 2, 3, or 4 wk after emergence (WAE) and thereafter done at 7‐ or 14‐d intervals. Control plants remained intact with no leaf harvesting. The number of lateral stems per plant, pods per plant, seeds per pod, unit seed weight, and vegetable and grain yields were monitored throughout each season, and plant productivity was found to be lower in intercropped than in monocropped cowpea. Leaf harvesting reduced all yield components. Initiating leaf harvesting at 3 and 4 WAE resulted in the highest leaf and grain yields, respectively. Harvesting leaves at a 7‐d interval was associated with higher leaf yield, while a 14‐d interval led to higher grain yield. Overall, yields were highest under treatments with no leaf harvest and lowest when leaf harvesting was initiated 2 WAE. Results of this study can help dual‐purpose cowpea growers optimize yields according to their production goals.