PHYSIOLOGICAL EVALUATION OF WHEAT GENOTYPES UNDER WATER DEFICIT STRESS

Abstract

To evaluate wheat genotypes under PEG induced water deficit stress during germination and early seedling growth twenty wheat genotypes were tested in three levels of water potential (Tap water, -2 bars and -4 bar) at Crop Physiology and Ecology Laboratory, Hajee Mohammad Danesh Science and Technology University, Dinajpur during September 2014 to October 2014. Speed of germination as expressed by rate of germination, co-efficient of germination and germination vigor index of all wheat genotypes were delayed with the increment of water stress induced by PEG. Shoot length and root length and seedling dry weight of 10 days old seedlings were found to be affected due to the increment of water stress. But the magnitude of reduction of these parameters with the increment of water stress were not similar to all wheat genotypes. Among the twenty wheat genotypes BARI Gom 25, E 28 and BAW 1170 showing higher Stress Tolerance Index (STI) and BAW 1140 showing the lowest Stress Tolerance Index (STI) based on seedling dry weight both at moderate and higher water deficit stress were selected as tolerant and sensitive genotypes. These four wheat genotypes grown under well water and water deficit stress condition at the research field of Crop Physiology and Ecology Department, Hajee Mohammad Danesh Science and Technology University, Dinajpur during the period of November 2014 to April 2015 to evaluate the drought sensitivity of wheat genotypes.Water deficit stress tolerant wheat genotypes showed greater stability of flag leaf chlorophyll, greater ability to retain water in leaf, higher level of proline in flag leaf and kernel, higher level of soluble sugar in flag leaf and greater ability to keep the canopy cooler compared to sensitive genotype under water deficit condition. Greater spike dry matter accumulation at peak, longer grain growth duration, better yield components such as spikes m-2and grains spike-1 under water deficit stress contributed to better tolerance of BARI Gom 25, E 28 and BAW 1170. The order of tolerance based on grain yield was BAW 1170 > BARI Gom 25 > E 28 > BAW 1140 and the order of tolerance based on above ground biological yield was BAW 1170 > E 28 > BARI Gom 25 > BAW 1140.