Physiological response of cowpea seed to ionising radiation

Fifteen (15) cowpea genotypes were radiated at five (5) doses of gamma radiation (0, 50, 100,150 and 2000y). The experiment was conducted in the laboratory using the randomised complete block design with four replicates. Data were collected daily on the number of germinated seeds for 14 days and parameters such as such as first day to germination, germination percentage, coefficient of velocity of germination and others and these were analysed using the analysis of variance procedure in GenStat and means were separated using the least significant differences test at P = 0.05. The results showed that significant differences existed between the genotypes in germination parameters such as percentage germination, time to 50% germination, mean germination rate, germination index and coefficient of velocity of germination. However, the dose ranges had no effect on these parameters. Significant interaction effect (P < 0.01) observed between the cowpea genotypes and the radiation doses in terms of germination percentage and germination index suggests that there were differential responses to the irradiation doses among the genotypes. Overall, low doses of ionising radiation appear to have little or no effects on both the proportion and time measurements of germination parameters in cowpea genotypes.