Identification of drought tolerant genotypes of soybean plant using principal component analysis and cluster analysis

Introduction The annual rain in Iran is about one third of world average (235-260 milliliters). Arid, semi-arid, super arid and desert weather conditions constitute about 85% of Iran’s area which is due to low rain in central and southern regions. The researches have shown that all the country is confronted with dryness that greatly affects agriculture. If this condition continues, generating agricultural products such as bean will definitely face some problems. Now, the global production of soybean is more than 310 million tons equals 80 billion dollars. Soybean is one of the important products in Iran’s agriculture. According to the last published statistics, the area under cultivation of soybean in country is about 80 thousand hectares and Golestan, Mazandaran and Ardabil have allocated the rank of first to third to themselves. Functionally, it is about 110 to 130 thousand tons per year. Soybean has nutritional value for human, livestock and soil. Since drought stress is the most important environmental stress which has severely led to reduction in plants’ growth, reduction of bush generation and function of crops more than any other environmental factor; thus, health of soil and environment is necessary to provide nutritional security in order to identify the resistant plants and their cultivation be developed. Numerous methods have been used to select the high quality items under the condition of stress in the farm and greenhouse. Regarding that the genetic base of resistance to drought stress has many complexities, proper and extensive phenotypic assessment on the farm together with identifying the desirable physiological features will be useful in natural environments. Hence, this plant and identifying the genotypes resistant to drought stress were carried out to develop the cultivation. Materials and methods To evaluate the dehydration and evaluation of tolerance to drought stress in soybean genotypes in 2017, a research was conducted as a factorial test in form of total random blocks in three repetition in greenhouse in Damsvand County. The first factor contained 50 soybean genotypes and second factor included two levels of normal irrigation and irrigation disruption in time of podding. Assessing genotypes was conducted by using tolerance to drought indexes: SNPI,MSTI,YR,RDI DI,ATI,SSPI, MP,GMP,HARM,SSI,STI,TOL,YI,YSI,. The dimensions of vases were about 35 in 45 centimeters which were filled by soil, sand and fertilizer in proportion of 1: 1: 3. Five seeds were planted in each vase. They were irrigated every four day. In time of stopping the irrigation, about 50% of pods were constituted. Cultivation was done on 10th of Tir, 2017. And statistical analysis were done by SAS and JMP software. Diagrams were drawn by Excel software. There are significant variety of soybeans. Results and discussion Comparisons showed that resistant and sensitive genotypes shall be separated on the basis of tolerance to drought indexes, as such that genotypes 2, 14, 21, 38, 49 indicated high function in both environment and genotypes 25 and 23 showed high function in stress conditions. In order to recognize the most effective indexes, the indexes which have the highest correlation with the weight of seeds in both stressful and lack of stress conditions will be reliable and according to the obtained conclusions, some of tolerance to drought indexes had the highest significant correlation with the function in normal ans stressful conditions. Decomposing into main components make this ability to differentiate between the indexes introducing resistant genotypes and the indexes introducing sensitive genotypes, and accordingly, cluster decomposition of 8 groups among 50 genotypes determined that finally some of genotypes had desirable function in both environments. In order to recognize the most effective indexes, the indexes which have the highest correlation with the weight of seeds in both stressful and lack of stress conditions will be reliable and according to the obtained conclusions, Harmonic mean(HARM), geometric mean productivity(GMP), mean productivity(MP), stress tolerance index(STI), yield index(YI), Abiotic tolerance index(ATI), Drought resistance index)DI), Yield stability index(YSI), Stress susceptibility percentage index (SNPI), modified stress tolerance index(MSTIk1 and MSTIk2) of tolerance to drought indexes had the highest significant correlation with the function in normal ans stressful conditions. genotypes 2, 14, 21, 23, 42 and 49 have suitable function in both environments.