Comprehensive evaluation of flowering-podding period drought resistance of soybean

Ten different ecotypes of soybean varieties were selected based on the degree of drought resistance.Some physiological and biochemical indexes related to drought resistance including relative conductivity,photosynthetic rate,relative water content,etc.were measured by way of pot and field experiments.Grey system theory was used to determine the relationship between indexes and drought resistance.Then by applying grey correlative degree,comprehensive multiple target evaluation and drought resistance index as parameters,every identified index was assigned an absolute value to quantitatively evaluate soybean drought-resistance in floweringpodding period.Results show the relative degrees of “Jinda 74”,“Jinda 53”,“Jinda 75”with the reference variety to be,respectively,0.8706,0.7278 and 0.5513.“Jinda 74”has the highest drought resistance,followed by“Jinda 53”,while “Jinda75” is simply the weakest.In accordance with drought resistant index theory and grey correlative degree of comprehensive multiple target evaluation,drought resistance of“Jinda 74”and“ Jinda 53”are the best,which well correspond with practical situations.Correlation coefficient of the two drought resistance appraisal methods of soybean is 0.8061^**,which explains the reliability of grey correlative degree in the use of comprehensive multiple target evaluation to evaluate soybean drought resistance in flowering podding period.