SCREENING OF COWPEA (Vigna unguiculata (L.) Walp.) GERMPLASMS FOR ADAPTATION TO DROUGHT IN THE SUDAN SAVANNA ZONE OF NIGERIA
Ismail Hamza, Yusuf Bala Daraja, Muhammad Usman Ladan and Ma’amun Da’u Aliyu
Keywords: cowpea; drought escape; drought tolerance; drought avoidance.
Cowpea is cultivated commonly as a rain-fed crop. However, annual rain ceases within five months in the Northern region, an area with a high production bulk. Despite the crop’s inherent capacity for withstanding stress more than any other legume, an erratic rainfall pattern exposes cowpea to drought early, mid or late in the cropping season, causing damage, injury, and low yield. Although high yield potential is the target of most crop breeding programs, and this could be achieved by the used high yield potential traits in a moderate stress environment. This study was carried out at IITA Research Farm, located near Wase Dam (120 03’N and 80 34’E) in the Sudan Savannah of Minjibir Local Government Area, about 20km northeast of the state capital Kano Nigeria; during the 2016 and 2017 dry seasons. The objectives are to evaluate the growth and yield attributing characters of 10 cowpea germplasms as they are influenced by genetic variations under drought imposed and also to determine genetic variations of drought response among the germplasms root system and related traits. The experiment was laid in a randomized complete block design (RCBD) and replicated three times. The results revealed that IT98K1092-2, IT97K-499-39, Tvu-11610, and Tvu-1000 were considered drought escape (flowered and matured early) with good yield characters. Delayed in flowering were discovered on Aloka local, Dan’ila, and Tvu-10408. Following were found with enhanced levels of drought tolerance IT98K1092-2, Tvu-10408, and Tvu-10302. Susceptibility to drought was recorded on Tvu-1000, Tvu-11610, and IT97K-499-39. Among the genotypes, Ife-brown, Dan’ila, Tvu1330, and Aloka local developed stay green character, widest root stem, long taproot, and deep (steep) architectural root system were regarded with drought avoidance. For developing more drought tolerance, it is recommended that cross genotypes with the character of drought escape (flowered and matured early), drought tolerance, and drought avoidance are the most promising traits for breeders to consider as potential parents. When the combination of such genes added to susceptible variety can increase yield, it gives more grower profit, thereby enhancing the economy to small scale farmers, particularly in the Sudan Savanna agro-ecological zone of Nigeria.