Physiology of wheat (Triticum aestivum L. genotypes during germination against salinity stress
The present investigation was carried out to identify physiological parameters for screening tolerant and susceptible wheat genotypes against salinity stress and to study the physiology of salinity stress tolerance for improvement of wheat genotypes against salinity stress. The salt solution was prepared by using NaCl: CaCl2:Na2SO4 in the ratio of 7:2:1 (w/v) and electrical conductivity of different salinity levels were maintained by using direct reading conductivity meter. Wheat seeds were sterilized by soaking in 0.1% HgCl2 for two minutes followed by thorough washing with de ionized water and germinating in Petri dishes lined with blotting paper. Screening of 20 genotypes was done on the basis of germination percent. Out of these, four wheat genotypes belonging to tolerant (Yangmat 6 Sonalika RIL 5, Yangmat 6 Sonalika RIL 20) and susceptible (Yangmat 6 Sonalika RIL 7, Yangmat 6 Sonalika RIL 13) groups were selected for present investigation to study the impact of salt stress on 8 day old seedling of wheat genotypes. The evaluation was based on assay of some physiological and biochemical parameters under laboratory conditions. Effect of salt stress on seed germination and seedling growth of four wheat genotypes (Yangmat 6 Sonalika RIL 5, Yangmat 6 Sonalika RIL 20, Yangmat 6Sonalika RIL 7, Yangmat 6 Sonalika RIL 13) were evaluated. It was evident that the salt solution reduced seed germination and seedling growth of wheat. On the value of percent reduction in seed germination, germination relative index (GRI) mobilization efficiency (ME) and vigour index (VI) the inhibitory effect of different salt stress was found maximum in susceptible genotypes (Yangmat 6 Sonalika RIL 7 and Yangmat 6 Sonalika RIL 13) followed by tolerant genotypes (Yangmat 6 Sonalika RIL 5 and Yangmat 6Sonalika RIL 20) On an average, the germination percentage, GRI, VI of the tolerant genotypes was significantly higher than that of susceptible genotypes. Salt stress on wheat seedlings exhibited inhibitory effect on reducing sugar, non reducing sugar, total sugar, protein content and activity of enzyme amylase while it had stimulatory effect on parameters such as content of starch, total free amino acids, proline, and activity of protease and peroxidase enzymes.