Effect of inoculation with vam-fungi and bradyrhizobium on growth and yield of soybean in Sindh

Inoculation of soybean seeds variety William 82 and NARC-II with rhizobase inocula of vesicular-arbuscular mycorrhizal (VAM) fungi - Glomus macrocarpum and G. warcupii and root nodule bacterium, Bradyrhizobium japonicum, showed an increase in VAM-infection and root nodulation over the control. An increase in fresh weight, dry weight and seed weight was also observed as compared to control. Combined inoculation of the VAM-fungi and Bradyrhizobium japonicum showed further increase in VAM-infection (28.6%) root nodulation (30.3%) fresh weight (14.5%), dry weight (15.5%) and seed weight (15.3%) as compared to their separate use. The combined inoculation of G. macrocarpum and B. japonicum in soybean var. William 82 gave the best result. Soybean (Glycine max (L.) Merrill,) a good source of protein and vegetable oil is grown to some extent everywhere in the world. In Pakistan, soybean is grown on 17.6 thousand hectares with an average yield of 423 kg/hec., mostly to meet the demand of edible oil. On account of the wide gap between production and consumption of edible oil in Pakistan, it is imperative to improve upon the yield of oilseed plants. Vesicular-arbuscular mycorrhizal (VAM) fungi form symbiotic association which enhance water and nutrient transport particularly phosphorus (P) and thereby increase growth and yield of many a crop plants (Ross V Harper, 1970; Safir Boyer V Gerdemann, 1971; Carling V Brown, 1980). Strains of Rhizobium and Bradyrhizobium on infection of compatible species of legume participate in the symbiotic association, root nodulation leading to more N-2 fixation, which increase growth and yield (Dixon V Wheeler, 1986). In recent years the effect of combined inoculation with VAM-fungi and Rhizobia have been reported to further increase the growth and yield of some crops including soybean Azcon, 1979; Bagyaraj et at., 1979; Young et al., 1988. The tripartite association of symbiotic VAM-fungi, root nodule bacteria Bradyrhizobium japonicum was investigated to find its effect on the promotion of growth and yield of soybean var. William 82 and NARC-II.