Yield Components of Cowpeas Grown in Two Environments
1985
Kahn, Brian A. | Stoffella, Peter J.
Nine cultivars of cowpea [Vigna unguiculata (L.) Walp.] were grown in Spring 1983 at Fort Pierce, FL (Alfic Arenic Haplaquods soil) and Bixby, OK (Typic Udifluvents soil). The objective was to identify yield components which were consistently related to seed yield in two diverse environments. Double-row plots with 0.46 m between the two rows within each plot and 1.64 m between the rows of adjacent plots were used at both locations, with a within-row spacing of 20 plants per meter. Irrigation was provided by a subsurface system in Florida and by sprinklers in Oklahoma. Cultivars were harvested individually as soon as the majority of the pods were dry. Eighty plants per cultivar were evaluated at each location for seed yield per plot and several potential morphological components of yield. Harvest indices averaged 0.17 in Florida and 0.31 in Oklahoma. Forage yields were high in Florida, perhaps due to high N fertilization, while seed yields were only slightly lower than in Oklahoma. Seed number per pod was highest in Florida while average seed size was greater in Oklahoma. Despite these differences, the same three-variable regression model (log forage yield per plot, log harvest index, and log pod number per plant) accounted for 92 and 99% of the variability in log seed yield per plot in Florida and Oklahoma, respectively. Seed number per pod and seed size provided little additional indication of crop yield. Pod number per plant was the single component most strongly and consistently related to seed yield. An increase in the number of pod-bearing peduncles is suggested as an appropriate objective when selecting for increased cowpea yield.
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