An experiment was conducted to investigate the effects of planting pigeonpea in May, June or July at Mokwa and June or July at Shika and Kano, Nigeria at population densities of 18·5×103, 27·8×103, 55·5×103, 111×103, 222×103 and 444×103 plants/ha on dry matter (DM) and seed yields of cultivars Local, UQ50, 3D8103, 3D8104, 3D8111 and 3D8112 in the 1974/75 season. Planting in May had no above-ground DM yield advantage over planting in June at Mokwa. Planting in June gave higher yields than planting in July irrespective of site, except for the short, early maturing, soya-type cultivar 3D8103 at Shika. Cultivar responses to density were inconsistent between sites and also between dates at Shika and Kano. Cultivars Local, UQ50 and 3D8104 showed the highest DM yield at all sites. Leaf DM yield tended to decline as planting was delayed but was highest at densities of 111×103 or 222×103 plants/ha for May and June-planted cultivars Local, UQ50, 3D8104 and 3D8112, which showed potential as feed supplements for poultry. Reasons were advanced for the variability in pod yield responses to planting date and density between the different pigeonpea cultivars. Root DM yields were proportional to above-ground DM yield but, over all cultivars, root yield was unaffected by planting date at Shika.
Seed yield was highest from the June sowing, cv. 3D8104 was the most productive and the optimum densities were 27·8×103 plants/ha for the larger-sized cultivars Local and UQ50, 55·5×103 plants/ha for the medium-sized cultivars 3D8104, 3D8111 and 3D8112, and 444×10 3 for cv. 3D8103. A complementary study over 13 years showed that the seed yield of intermediate and late maturing pigeonpeas was strongly and linearly related to total annual rainfall.