Use of successional sowing in evaluating cowpea (Vigna unguiculata) adaptation to drought in the Sudan savannah zone. 1. Seed yield response

Abstract

SUMMARYTwo sets of experiments were conducted on oxic Plinthustalf and udic Ustochrept soils in 1983–85 at Ouagadougou, Burkina Faso. One set tested six daylength-insensitive (DI) cultivars and the other set compared four or five daylength-sensitive (DS) cultivars with one or two DI cultivars as controls, sown on three or four dates. Sowing date, cultivar and their interaction significantly affected seed yield in 1983 and 1985. In 1984, yield was not affected by sowing date in the DI cultivars nor by the sowing date x cultivar interaction in the DS cultivars. Optimum sowing dates were mid- and late July. Sowing earlier gave no yield advantage, whereas sowing later reduced yield severely.The medium-maturing DI cultivar TN88–63 and the DS cultivar Koakin Local, which has a critical photoperiod in late August, exhibited average to below average yield stability but had a high mean yield and were considered well adapted in all conditions. The other cultivars were either moderately or poorly adapted to the Sudan savannah zone. The sowing date experiments were effective in identifying adapted cowpea cultivars, even from a single year's data, and can be used for screening cowpea for adaptation in the Sudan savannah zone.