Effect of heats stress on the germination of thirteen cowpea (Vigna unguiculata L. Walp) released varieties in West Africa

Climate change presents scenarios of extreme temperature variations that will limit agricultural productivity further when the need for efficient production systems cannot be over emphasized. Aside breeding for tolerance, the development of new varieties of crops such as Cowpea, it is important to evaluate the temperature tolerance of new varieties prior to their release and commercialization. Therefore, in this study we evaluated the effect of the high temperatures on germination of 13 newly developed cowpea varieties resistant to major insect’s pest and drought under laboratory conditions. The 13 cowpea varieties were evaluated for germination at 10°C, 20°C, 30°C, 35°C and 40°C. There was no germination for all the varieties at the extremes of 10°C and 40°C. However, at 20°C high germination percentage was recorded on the varieties IT93K-452-1 (100%), IT97K-499-35 (100%), Komcalle (100%), Kumassi (93.33%), Tvu-1509 (100%) while at 30°C the high germination percentage was recorded on Agbloto (100°C), Akounado (93.33%), FUAMPEA1 (96.67%), FUAMPEA2 (93.33%), IT97K-499-35 (100%), IT97K-556-6 (83.33%), Komcalle (100%), Sanzi (90%). The temperature 35°C only provided high (100%) germination percentage for Komcalle. The variety TVU-1509 had the highest speed of germination. The variety IT 98K-205-8, and TVU-1509 had the highest homogeneity at the different temperatures. The results provide useful information for breeders on which varieties to release in a target environment and in formulating efficient selection and breeding programs. Keywords: Cowpea, germinability; mean germination time, coefficient of velocity of germination, synchrony