Effect of drought stress on morphological and biochemical characteristics of soybean genotypes in the second crop

In order to investigate the morphophysiological response of soybean (Glysin max L.) to drought stress as second crop, an experiment was conducted in Lorestan Agricultural Research Center in the summer of 2017 and 2018 in two environments including normal and drought stress condition. In each environment, 19 soybean genotypes were studied in a randomized complete block design with three replications. The results showed that all traits except leaf temperature decreased due to drought stress. Mean comparison showed that the highest leaf temperature was obtained from genotype No. 9 in stress environment and the lowest was obtained from genotypes No. 4 and 15 in normal environment (27.5 and 13.2 ° C, respectively). The highest grain yield was obtained from genotype No. 7 in normal environment and the lowest from genotype No. 19 in stress environment (4894 and 275 kg/ha, respectively). The analysis of biochemical traits of shoots showed that the amount of unstructured soluble sugars and free proline increased with drought stress from (1.87 and 0.0028 mg, respectively) in normal environment to (3.77 and 0.0054 mg/g fresh weight, respectively) in stress environment. Among the genotypes, the highest and the lowest amount of shoot proline were obtained from genotype No. 4 (mg/g fresh weight) and genotype No. 1 (0.043 and 0.03777 mg/g fresh weight, respectively), respectively. In addition, genotypes No. 7 and 9 can be recommended for normal and stress conditions in moderate region such as Khorramabad.