Effect of intensity and frequency of leaf harvesting on growth, nodulation, and yield of selected cowpea varieties
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Cowpea; Defoliation; Frequency; Intensity; Variety
Cowpea (Vigna unguiculata (L.) Walp) is a leguminous crop widely cultivated across the world and is considered more useful than other vegetables particularly in Sub-Saharan Africa. The objective of this study was to determine the effect of intensity and interval of leaf harvesting on growth, nodulation, and yield of cowpea varieties M66, Lubia and Areng in South Sudan. The experiment was set up at Awerial and Bor sites in South Sudan in a randomized complete block design (RCBD) in a 4×3×3 factorial arrangement. The factors evaluated were cowpea variety at three levels (M66, Lubia and Areng), intensity at four levels (0%, 20%, 40% and 60%) and interval of leaf harvesting at three levels (2, 3 and 4 weeks). Cowpea variety Areng had the best performance among the three varieties evaluated. Areng took 52 days to flower and 108.7 days to attain maturity followed by Lubia and M66 which took the shortest time to flower and reach maturity. In contrast, the highest number of nodules of 124 at vegetative and 136 at flowering stage was observed on variety M66 followed by Areng while the lowest number of nodules was observed on variety Lubia. Effects due to environment, variety, interval, and intensity were significant (p≤0.001) for days to flowering, maturity, number of nodules at flowering, weight of pod, grain weight, shoot fresh weight and shoot dry weight at flowering stages. Harvesting intensity and interval has significant effect on yield and yield components of cowpea varieties and therefore, cowpea variety Areng is suitable for seed weight and foliage harvesting because irrespective of intensity of leaf harvesting, the dry matter was not reduced to a level that can affect production. Moreover, the variety M66 was the best in grain weight across and within sites.