Abstract

In the tropics, high temperatures and nutrient inaccessibility are often the most limiting factors affecting plant growth and final crop yield. However, it remain incomprehensible the actual impact of simultaneous interaction of prior heat stress and nutrient addition on growth and yield of cowpea plant, knowing that  cowpea plant is an important grain legumes for over 200 million people in dry savanna of tropical Africa. In this study, the effect of interaction between prior heat stress and nutrient addition on growth and yield of cowpea plant was carried out in a randomized pot experiment at Obafemi Awolowo University, Ile-Ife, Nigeria. Cowpea seedlings were exposed to prior heat stress of 40°C a week after germination and different level of nutrient addition. The result obtained from the study showed that there was no significant (p<0.05) difference in the interactive effect of nutrient addition and prior heat stress on the shoot height of cowpea in most of the treatments compared to control, except in NNH₃ (200 ml of the nutrient solution on daily basis and 3 h of prior heat stress) and N₅H₆ (200 ml of nutrient in every five days and six hours of prior heat stress)_. The shoot height of N₅H₆ was significantly higher (41.17) than NNH₃ (20.26 cm). Cowpea plant subjected to only water with no prior heat stress had the highest leaf dry weight (2.44 g), while the cowpea plant under the interactive effect of nutrient supplied at every five days and six hours of prior heat stress had the highest shoot dry weight (2.63 g). The feedback of cowpea plant to interactive effect of prior heat stress and nutrient addition indicated that Longer period of prior heat stress had better advantages on growth parameter cowpea plant. However, neither prior heat stress nor nutrients addition had significant benefit on the leaf yield of cowpea, the interaction of the two significantly benefit shoot biomass and pod number of Cowpea plant.

Key words: Cowpea, growth, nutrient. heat, nodule, stress, treatment, yield.