EFFECT OF COBALT-60 GAMMA IRRADIATION ON VIABILITY OF SOYBEAN (Glycine max . L) SEED

Abstract

The rapid rate of deterioration and low viability of soybean seeds particularly in storage is a major constraint to its production in the subtropical and tropical areas. Various approaches have been made to solve this problem but they have centred mainly on the control of the environment. Experimental mutagenesis is one of the ways by which genetic variability could be created to serve as basis for selection. In this study, induced mutations were used to create genetic variation and mutants with improved storability selected to provide a more lasting solution to this problem. Seeds of three soybean varieties - Grnx 92-6-10 , Gmx 92-5-4 E and TGX 87D - 1303 were subjected to four (4) months ambient storage and three accelerated ageing tests. The germination percentages computed 7 days after planting showed that 20%) ethanol solution better mimicked ambient storage than 20% methanol solution and the 75°C hot water. In the radiation dosage response studies, dry seeds containing 10% moisture from the three varieties were subjected to 0, 50, 100, 150, 200 and 250 Gy doses of 60Co gamma rays at Ghana Atomic Energy Commission, Kwabenya and sown. The 250 Gy dose reduced both germination percentage and plant height by about 50% relative to the control and was used as the dosage appropriate for induced mutations for the varieties.