Induced variation for post-emergence herbicide tolerance in lentil.

Abstract Lentil (Lens culinaris L. Medik.) is an important cool-season food legume but is a poor competitor to weeds because of a slow early growth rate. If weeds are left uncontrolled, they can reduce yield by up to 50%. Sensitivity of lentil to post-emergence herbicides warrants development of herbicide-tolerant cultivars. In the absence of natural variability, mutation breeding is a powerful tool to create variability for desired traits. Thus, 1000 seeds of a lentil genotype, LL1203, were exposed to gamma radiation (300 Gy, 60Co) with the objective to induce herbicide tolerance. Seeds of all 530 surviving M1 plants were harvested individually and divided in two parts to raise the M2 generation in two different plots. Each plot was sprayed with imazethapyr (75 g/ha) and metribuzin (250 g/ha) herbicides 50 days after sowing, using water at 375 l/ha. Data on herbicide tolerance for individual M2 plants were recorded after 14 days of herbicide spray on a 1-5 scale, where 1 = highly tolerant (plants free from chlorosis or wilting) and 5 = highly sensitive (leaves and tender branches completely burnt). For herbicide-tolerant M2 plants, data were also recorded for pod and yield per plant. None of the M2 plants showed a high level of tolerance to imazethapyr. However, 14 mutants having higher herbicide tolerance to metribuzin were selected. Two mutants ('LL1203-MM10', 'LL1203-MM7') recorded < 2.0 score, while six mutants recorded < 2.50 score as compared with the 3.13 score of the parent variety. The pods per plant and seed yield per plant of mutants 'LL1203-MM7' (383 and 12.4 g) and 'LL1203-MM10' (347 and 12.1 g) were higher than those of the parent genotype LL1203 (253 and 7.8 g). The study indicated that metribuzin-tolerant mutants have some other desirable traits that can be of use in lentil breeding.