Physiological Parameters of Salt Tolerance in Wheat
A solution culture experiment was conducted in wire house of the Department of Soil Science and Agricultural Chemistry, Zhejiang Agricultural University, Hangzhou, P.R.China with natural daylight and day/night temperature of 17/7 oC respectively with the objective to correlate the results of different physiological parameters with salt tolerance of cultivars under 100 and 200 mol m -3 NaCl salinity. The two Chinese cultivars used were Bao-119, CV.86-6 and one Pakistani was FSD-85. The results of this study indicate, that with the gradual increase of salinity dry weight of shoot and root, potassium, calcium contents both in shoot and root and leaf area decreased, where as sodium, chloride and chlorophyll contents increased in all the cultivars except chlorophyll contents decreased at 100 mol m -3 salinity in Bao-119. Photosynthesis increased at 100 mol m -3 salinity and decreased at 200 mol m -3 salinity in all cultivars. The tolerance of cultivars on cumulative dry weight means (3 treatments) was in order of CV.86-6 > FSD-85 > Bao-119 whereas at 200 mol m -3 salinity was as FSD-85 > CV.86-6 > Bao-119. The cultivars FSD-85 and CV.86-6 showed salt inclusion and exclusion mechanisms respectively at 200 mol m -3 salinity in relation to ionic composition. Consistent pattern was found between relative leaf area and dry weight of shoot at 200 mol m -3 salinity and on cumulative mean (3 treatments) basis. In-consistent pattern was found among chlorophyll contents, photosynthesis rates and tolerance of cultivars at both the salinity levels. From this study it was also concluded, that before the detail study of mechanisms of salt tolerance, the following considerations are also essential for the authenticity of the proposed tolerant and sensitive cultivars. The cultivars under test must grow under uniform conditions and must receive their own optimum requirements, and sampling for analysis of different parameters must be done after the same duration of stress and preferably from same plant parts. In the absence of the above, it is difficult to correlate the results obtained from analysis of different physiological parameters.
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