ASSESSMENT OF SCREENING TECHNIQUES FOR HEAT TOLERANCE IN WHEAT

Heat causes considerable damage to the wheat (Triticum aestivum L. em Thell.) plant. The present method of assessing heat tolerance in wheat , which is based on cell membrane thermostability, is not efficient fo r screening large numbers of genotypes. This study compares the effici encies of two modified methods with that of the original method for me asuring heat damage in wheat genotypes. Percent heat damage was analyz ed by an errors-in-variables approach. Measurements of the original me thod were regressed on measurements of the new methods. The first modi fied method, is 25% more efficient than the original method and posses ses similar accuracy. In the second method, the slope differed from un ity by 3% and the intercept was - 3.2 1, but the ranks of the tested g enotypes did not change. Therefore, for screening heat-tolerant genoty pes relative to a check, the second method, which is 50% more efficien t than the original method, is recommended because the relative classi fication of genotypes into tolerant and susceptible groups does not ch ange with a constant difference in the measurements.