Abstract
Farmers have adopted new soybeans varieties developed by research institutes that have early maturity, high grain yielding, as well as other good agronomic traits. However, there is limited variability among the soybeans in germplasm cultivated in Nigeria. The aim of this study was to determine the morphological characters of soybeans (Glycine max L.) treatment with gamma radiation as a means of inducing beneficial mutations. This was performed by exposing two varieties of soybeans (TGX 1835 and TGX 1987) to gamma rays at doses of 0 (control), 5, 10, 15 and 20 Gy. The parameters measured include establishment count, plant height, number of branches per plant, number of leaves per plant, number of pods per plant, days to 50% podding, 100 – seeds weight and total grain yielded. The results showed a symmetric reduction in plant establishment count in all the mutagenic treatments compared to the control (O Dose Gy). Comparison of the plant height showed that TGX 1987 and 1835 at 10 Gy produced the highest plant height at 8 and 10 WAS. While there were no significant differences in all the treatments at 6 WAS in chlorophyll content but there was significant difference at 10 WAS. The results showed that at 10 WAS TGX 1835 at 10 Gy produce highest branch numbers. The result also showed that there was a significant difference in number of leaves per plant at 10 WAS with highest leaves number (183.33 leaves). The data on the days to 50% flowering showed that TGX 1835 gives the shorter days (38.66a) to 50% flowering at 20 Gy. The highest number of pods per plant was observed in control treatments in all the varieties. The result showed that the highest total grain yield was observed in TGX 1835 at 20 Gy and the lowest yield was observed in TGX 1987 at 5Gy. It can be recommended from this work that 20 Gy and 15Gy could be used to create variability in soybeans.