Effects of drought stress on yield and yield component of soybean genotypes

Experiments were performed with 49 soybean genotypes from I II and III maturity groups on base of lattice 7*7 designs at two replications and two levels normal (60 mm) and stress (150mm) in field of seed and plant breeding research institute in karaj in summer of 1383. At duration of the experiments were took notes from phenologic traits and were took notes from yield, yield components, oil and protein percents after field harvest, too. Results of analysis of variance indicated a good diversity between genotypes for almost traits. Path and stepwise regression analysis showed seed number in plant and biomass have most effects on yield in normal and stress conditions, respectively. Factor analysis indicated 5 affected factors in normal condition and 4 affected factors in stress conditions. Traits such as pod on reproductive nodules, plant seed number associated with yield in normal conditions and characters such as 100seed weight, root weight and biomass associated with yield in stress conditions, too. Calculation of resistance indices and biplot analysis divided genotypes to 4 groups and indices such as MP, STI, GMP and Harm were recognized as best drought indices in soybean. Obtained results of biplot analysis and drought resistance indices recognized genotypes such as Maccon, cysen,L.D.8149 have high yield and drought resistance and genotypes such as Korona, Hadgson and Enterprise have low yield and susceptible to drought.