Influence of temperature regimes on drought stress tolerance of cowpea genotypes in Northern Guinea savannah, Nigeria

Abstract

Drought is a major constraint that affects cowpea production in Zaria, Nigeria. It is unpredictable, and occurs at any growth stage of cowpea. Changes in global climatic trends
are consistently narrowing the cowpea growing season in Northern Nigeria by gradually
pushing its cultivation towards drought-prone, colder temperatures. The study aimed to elucidate foresight data on the tolerance of cowpea landraces to drought at cold and hot
temperatures in a bid to harness available germplasm towards mitigating climatic changes.
Seedling drought tolerance of four hundred and twenty-two (422) cowpea genotypes obtained
from farmers’ collection (308) and the International Institute of Tropical Agriculture (IITA) (114) was evaluated by adopting the wooden box method. The parameters evaluated were number of plants, plant height, number of trifoliate, leaf senescence, stem greenness, and recovery. The mean square values for all evaluated traits were significant (p ≤ 0.05). Leaf senescence progressed rapidly in cooler temperatures (6 ^oC - 18 ^oC). Interestingly, the recovery rate upon reintroduction of water after drought stress was higher in cold temperatures. The percentage recovery and stem greenness of drought-tolerant plants were positively associated with hot temperatures (22 ^oC - 36 ^oC). As cowpea production is pushed into colder planting season, the resilience shown by cowpea landraces in northern Nigeria are positive.