GROUNDNUT IMPROVEMENT: INDUCED GENETIC VARIABILITY FOR YIELD AND ITS COMPONENTS IN GROUNDNUT (Arachis hypogaea L.) THROUGH GAMMA IRRADIATION

Groundnut is considered as a one of the principal economic oilseed crops of the world, which has been exposed extensively to mutagenic treatments for genetic variability induction. The present investigation aims to study the genetic variability, for yield and yield components of some mutant lines derived from two different genotypes i.e., Giza-6 and NC-1 under four levels of gamma rays (0, 100, 200 and 300 Gy). In M1 generation, over the genotypes, significant effects of gamma irradiation doses was detected for pod yield plant-1 and seed yield plant-1, among the various dose of gamma ray treatments, the low level dose (100 Gy) caused the higher increase of pod yield plant -1 (21.87%) and seed yield plant-1 ( 21.4%) as compared to a control treatment. Concerning the M2 generation a wide range of genetic variability was detected for most quantitative studied traits as evidenced by higher mean, range, standard deviation (SD) and coefficient of variability (CV%). Moreover, in M2 generation, the gamma irradiation dose at 100 Gy increased significantly seed yield by 30.9% for Giza-6 and 27.5 % for NC-1 as compared to control treatment. Also, the pod yield in gm. plant-1 was increased by 44.2% for Giza- 6 and 50.6% for NC-1 as compared to control treatment, for the number of seeds per plant, there was a significant increase of 36.8% for Giza 6, and 44.3% for NC1 as compared to control treatment. On the other hand, higher dose of gamma rays (300 GY) caused significant reduction in plant growth and grain yield and the other contribution traits. Further genetic improvement through selection for yield improvement should rely on the pod yield plant-1 and seed number plant-1, these mutants recorded higher genetic variability for all quantitative traits. Seed yield exhibited significantly positive correlation with pod yield plant1 (r=0.91) and seed number plant-1 (r=0.95) for both genotypes. These results clearly indicate that indirect selection for yield in groundnut is possible through simultaneous improvement of these yield components in the promising mutant lines.