Evaluation of tolerance and resistance to flooding stress in different soybean varieties

Introduction Due to inappropriate irrigation methods, poor drainage in the fields and also warming the planet, flood stress has become an important stress in recent years for crops. On the other hand, due to the importance of soybean in supplying oil and animal feed, sufficient information is available on soybean flooding stress tolerant cultivars or lines in Iran Which have a high yield under flooding stress conditions, Does not exist. Therefore, this experiment In order to select soybean genotypes tolerant to flood stress in the country based on seed yield, seed yield components and tolerance and stress resistance indices. Materials and methods This experiment was conducted as factorial in a completely randomized design with 3 replications and two factors: 1- flooding stress (no flooding stress and 15 days flooding stress) and 2- cultivars (31 soybeans cultivar and lines). Time of action flooding stress was 5-leaf stage (V5). In this experiment, seed yield and biological yield of soybeans, components yield of soybean (number of pods per plant, number of seeds per pod, 100 seed weight), and tolerance and stress resistance indices were measured and calculated. Data analysis was done using SAS software and drawings of diagrams and forms with Excel software. Results and discussion The results of this experiment showed that flooding stress significantly reduces the seed yield and biological yield of soybeans, So that the seed yield for 15 days of flooding stress decreased from 40.6 to 61.7% and biological yields decreased by 17% to 44% during 15 days of flooding stress. The highest seed yield after 15 days of flooding in 326 and 827 cultivars, and the lowest seed yield after 15 days of flooding was observed in cultivars 114 and 937. The results of this experiment also showed that GMP, MP and STI indices have a very high correlation with seed yield under stress conditions and these three indicators can be used to select high yield cultivars under stress and non stress conditions. Based on SSI, STI, MP and GMP indices cultivars 859, 827 and 326 are the most resistant cultivars among the cultivars studied in this experiment. Acknowledgements In general, according to the results of this experiment, soybean varieties do not differ much in terms of response to flood stress and among 31 soybean varieties studied three varietie of 859, 827 and 326 have a good tolerance to flooding stress have and in conditions without flooding stress and in flooding stress conditions seed yield is acceptable.