Responses of linseed genotypes to salinity stress during early seedling growth

E S H Salinity is an important abiotic stress causing severe reduction in early seedling growth, plant stand and crop yield. Linseed (Linum usitatissimum L.) is known to be one of the oldest versatile crops having medium salt tolerant characteristics. The study aimed to evaluate the effects of salinity stress induced by NaCl on the early seedling growth of 29 linseed genotypes under 5 salinity levels (0, 4, 8, 12 and 16 dS m-1) during the winter season of 2019-2020. The results showed that early seedling growth related parameters such as fresh and dry weights, and root length and shoot length of seedling, root to shoot ratio, seedling vigor index and salt tolerant index were decreased gradually with the increasing salinity level. The reduction in these traits was positively and significantly correlated with salinity levels. Compared to control, NaCl treatments of 4, 8, 12 and 16 dS m-1 caused reduction in seedling dry weight, fresh weight, shoot length by (33.82, 46.08, 54.14 and 77.34%), (11.69, 25.35, 38.31 and 51.97%), (36.36, 50.00, 54.55 and 77.27%), and (15.30, 24.76, 39.69 and 50.77%), respectively. Root to shoot ratio was more or less similar in 7 genotypes, while it was significantly increased in 6 genotypes at all salinity levels. The ratio was increased significantly over control at 16 dS m-1 in other 7 genotypes, and at 12 and 16 dS m-1 in 9 genotypes. In 29 genotypes, the average reduction in seedling vigor index was 37.27, 52.21, 64.28 and 84.57% respectively at 4, 8, 12 and 16 dS m-1. The highest mean seedling vigor index (SVI) was recorded from Neela followed by Lin-W-17, Lin-503, Lin-1403 and Lin-2403, while the lowest was found in BD-7143 (6.06) followed by Chilmari (6.46) and BD-7142. The average salt tolerant index of dry weight of whole seedling varied from 52.28 to 54.84% among 29 genotypes. Ten genotypes showed more than 60% tolerant level. Considering high level of early seedling growth and salt tolerance genotypes Neela, Lin-W-17, B-10708, BD-10710, Lin-1303, Lin-2403, BD-10698, Lin-S-19, BD-7143 and Lin-503 were noted as prospective materials for the develop0ment of salt tolerant linseed varieties.