Mutagenic effects of gamma rays on vegetative growth of three sesame (Sesamum indicum L.) varieties

Abstract

The effects of gamma irradiation on three Nigerian sesame varieties: NCRIBEN 04E, NCRIBEN 01M and NCRIBEN 03L was observed to determine the genetic variability of the varieties due to the irradiation treatment. Three grams (3g) of each variety was divided into five groups and exposed to gamma irradiation from the Cobalt-60 source at 50, 100, 150 and 200 Gy; with the fifth group being an un-irradiated control (tagged as 0 Gy). The irradiated seeds along with their respective controls were grown to maturity using a Factorial Experiment with Complete Randomised Block Design Method. There were significant differences (P ≤ 0.05) between the plants of each variety at the different doses of gamma irradiation for the emergence count, germination percentage, plant height, length of petiole, number of leaves per plant and leaf surface area observed. The results recorded no significant difference (P ≤ 0.05) in the emergence count and germination percentage of the NCRIBEN 04E variety in both the control and the 50 Gy dose (7.67 and 84.67%respectively). The highest germination percentage (90%) was observed in the NCRIBEN 03L variety at the 200 Gy dose. NCRIBEN 04E recorded the highest plant height at 6 weeks after planting (20.86 cm) at 150 Gy dose. This value was significantly different from the control (16.31 cm). The highest number of capsules in NCRIBEN 03L variety (26.17) was recorded at the 200 Gy dose and its lowest value (11.83) was recorded in the 100 Gy dose. The NCRIBEN 01M variety recorded the highest surface area at the 100 Gy dose (28.25 cm2). It was observed that there were significant positive correlations (P ≤ 0.05) between the plant height with increasing irradiation doses of NCRIBEN 04E at the 4th (0.745) and 6th week after planting (0.705). A significant positive correlation (0.847) was also recorded between the leaf surface area and irradiation doses of the NCRIBEN 03L variety. This observed variability for the vegetative parameters with varying doses of gamma irradiation is an indication of the possibilities of gamma rays in causing variations that could be explored for further improvement of the sesame varieties.