EFFECTS OF COBALT-60 GAMMA IRRADIATION ON GROWTH AND YIELD OF PEARL MILLET (Pennisetum glaucum L.) IN THE GUINEA SAVANNAH AGROECOLOGICAL ZONE OF GHANA

Abstract

Millet remains a neglected and under-utilized crop with low yields under the local environmental conditions. Four experiments namely Experiment I (M1 generation/dosage response study), Experiment II (M1 generation/field study), Experiment III (M2 generation) and Experiment IV (M3 generation) were carried out at the University for Development Studies, Tamale, Ghana, from June to July, 2014; August to November 2014; December 2014 to March 2015 and May to July 2015, respectively. Treatments used in Experiment I were made up of 7 gamma ray doses; 100, 200, 300, 400, 500, 600, 700 Gy and a control (0 Gy). Experiment (dosage response study) was conducted to assess the sensitivity of pearl millet variety Naara to gamma irradiation. Parameters measured were seed germination percentage, seedling survival and seedling height. Results of the study indicated that gamma ray doses 400, 500, 600 and 700 Gy reduced seed germination and were lethal as they resulted in more than 50% reduction in seedling survival. Hence these doses were eliminated from subsequent experiments. The LD50 was predicted to be 309 Gy. In the M 1, M2 and M3 studies, the effect of gamma irradiation on growth and yield of pearl millet variety Naara were investigated. Parameters measured were seed germination, plant survival, plant height, number of tillers and productive tillers, earliness to flowering, head length, width and weight, 100 seed weight and grain yield. The 100 Gy predominantly produced plants with higher values in almost all parameters measured in all the generations. Though, 200 and 300 Gy gamma ray doses performed less than the control in some parameters measured in the M1 generation, their performance subsequently increased progressively in the M2 and M3 generations. In the M3 generation, all gamma ray doses improved all parameters measured, however, plant height and number of tillers were decreased by 100 Gy gamma ray dose. The study therefore recommends that promising lines selected from the M3 generation be advanced to further generations. Studies in the nearest future generations should be broadened to include nutritional and molecular analysis of selected promising mutant lines.