Path analysis of grain yield and related traits of different lines of soybeans in Golestan province

In order to study the grain yield and related traits of soybean pure lines in year 2008, 141 pure lines of soybean with three checks (Williams, Sahar and DPX) were evaluated in a simple 12×12 lattice, with two replication at the Agriculture and Natural Resource Research center of Golestan. The analysis of variance results showed that there were significant difference among genotypes for most of the traits which indicates the existence of genetic variations between genotypes. Results showed that grain yield was positively and significantly correlated with traits; days to flowering, plant height, number of branches, number of pods per plant, weight of seed per plant (gram) and percentage of protein. There were also significant and negative correlation between grain yield with oil percent, Step wise regression showed that traits; days to flowering, plant height, number of seeds per pod, number of nod per plant and percentage of protein could justify the highest variations for grain yield. Path analysis showed that the highest and least direct effect on grain yield were number of pods per plant (P=0.29) and percentageof protein (P=-0.26). According to the result number of pods per plant was identified as a selection criteria for improvement grain yield.