EFFECT OF GAMMA RADIATION ON GERMINATION AND SEEDLING SURVIVAL IN THE PACHEQUEÑO SESAME VARIETY

Abstract

The low genetic variability of introduced species represents a limitation for plant breeding programs, this being very marked in sesame (Sesamun indicum L.), this variability could be increased through mutagenesis. The aim of this study was to evaluate the effect of gamma radiation on germination, vigor, and seedling survival in the variety Pachequeño of sesame. Seeds were treated with 14 doses of 60Co gamma rays (0, 25, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 Gy) and sown in 200-well trays under a completely randomized design with five replicates. The variables evaluated were germination percentage, emergence speed, seedling height, root length, survival percentage, and median lethal dose. Results indicated significant differences (P ≤ 0.0001) in all variables. In survival, the applied doses of 100, 250 and 300 Gy showed values of 95.0, 95.0 and 100.0 %, respectively by radiostimulation effect in relation to the control (76.35 %), while for the 600 Gy dose a significant decrease was observed to 39.17 %. In emergence speed, the 100, 150, 200 and 250 Gy treatments were superior to the 600 Gy dose. At doses of 25 to 450 Gy there was increased root development. Germination at the sixth day ranged between 8 and 95 %, while the control showed 69 % . Multivariate analysis indicated that the first two principal components were the most relevant, explaining 88.4% of the total variance, the first one as a general indicator of vigor, and the second one by emergence speed. Linear regression indicated that the median lethal dose in sesame seeds was 605.5 Gy. In general, intermediate doses can produce individuals with greater vigor, favoring selection by inducing effective mutations.