EVALUATION OF GAMMA RADIATION-INDUCED MUTANT LINES OF SESAME (SESAMUM INDICUM L.) FOR GENETIC IMPROVEMENT OF SOME DESIRABLE TRAITS

Abstract

The creation, evaluation and selection of mutants with desirable traits have served as source of genetic variability for breeding programmes of many crops. Thus, eleven mutant lines of sesame developed through induced gamma irradiation were evaluated in the M4 generation alongside the three parental varieties [NCRIBEN 04E (check-1), NCRIBEN 01M (check-2) and NCRIBEN 03L (check-3)]. The mutant lines and their respective checks were laid in a randomized complete block design (RCBD) with three replicates each. All the parameters were studied following standard procedures. The results of vegetative parameters revealed that mutant lines ML-6 (123.83 cm) and ML-8 (121.59 cm) had highest plant height at maturity with 5 % level of significance while ML-7 had the highest number of branches per plant. There was no significant difference (P ˃ 0.05) in number of days to 50 % flowering. ML-2 (77.30), ML-3 (105.33), ML-7 (151.00) and ML-8 (163.00) produced higher number of capsules per plant than their respective checks. Mutant lines with improved capsule characteristics comprised of ML-2 (2-3 capsules per leaf axil), ML-6 (1-2 capsules per leaf axil), ML-9 (1-2 capsules per leaf axil), ML-10 (2-3 capsules per leaf axil) and ML-11 (1-3 capsules per leaf axil). All the M4 mutants had adequate pollen viabilities (over 80 %). The highest pollen germinability was recorded at 20 % sucrose concentration for all the mutant lines. Suboblate shaped pollens with 10-13 colpi were observed in all the mutant lines and the checks. Significant increase was observed in oil contents of ML-2 (40.32 %) and ML- 10 (40.05 %) over their check groups. All mutants derived from Check-1 [ML-1 (22.83 %), ML-2 (28.63 %), ML-3 (27.41 %)] and Check-2 [ML-4 (23.72 %), ML-5 (22.85 %), ML-6 (23.41 %) and ML-7 (32.83 %)] showed significant enhancements in protein content of the seeds with ML-7 (32.83 %) having the highest value. Similarly, all mutants showed significantly higher (P ˂ 0.05) moisture contents than their checks except ML-8 (3.38 %). ML-10 (0.303 %) had the highest tannin value while the least oxalate and phytate contents were recorded in ML-1 (2.545 %) and Check-2 (0.532 %), respectively. All the mutants obtained from check-1 and check-3 showed significantly higher free fatty acid except ML-8 (1.13 %). Result on oil composition revealed that the physical properties of oil obtained from all the mutant lines and checks are within the acceptable limits by Codex. The variability observed in morphological, yield, seed nutritional composition and oil properties of the M4 lines reflects the existence of genetic diversity as a result of gamma irradiation and suggests potential genetic improvements for sesame. Mutant lines with higher pollen viability could be used as male parents in controlled pollinations for increasing the productivity of sesame and further improvement of the crop.