a1 International Institute of Tropical Agriculture (LITA), Kano Station, Sabo Bakin Zuwo Road, PMB 3112, Kano, Nigeria
a2 University of Reading, Department of Agriculture, Plant Environment Laboratory, Cutbush Lane, Shinfield, Reading RG2 9AD, Berkshire, England
Twenty-nine diverse genotypes of cowpea (Vigna unguiculata) were grown in approximately 30 photothermal environments in Nigeria and Niger, with mean temperatures ranging from 19° to 30°C, photoperiods from 10 to 16 h d−1 and saturation deficits from 0.5 to 3.1 kPa. Twelve of these genotypes were insensitive to photoperiod. The time of flowering of these photoperiodinsensitive genotypes showed a similar response to temperature. Time to flowering was also delayed by mean pre-flowering saturation deficits greater than 1.5 kPa. The implications of these responses to temperature and saturation deficit for phenological adaptation in West Africa are discussed.
(Accepted March 17 1995)
p1 Present address: University of Reading, Department of Agriculture, Plant Environment Laboratory, Cutbush Lane, Shinfield, Reading, RG2 9AD, Berkshire, England.