General and applied plant physioloGy -2010

Abstract

Summary. Gramineous plants establish strong symbiosis with arbuscular mycorrhizal fungi that can improve the uptake of P from soil. They also associate with some diazotrophic bacteria and get biologically fixed nitrogen. Sorghum bicolor is a sugar-rich multipurpose fodder crop well suited to dry farming. In the present study, S. bicolor plants were grown in a green house and the impact of inoculation with Herbaspirillum seropedicae and Glomus fasciculatum on growth, N and P nutrition of the plant was studied. A single inoculation with either H. seropedicae or G. fasciculatum supported plant growth promotion effect resulting in enhanced root length (5-7%), shoot length (18-22%), root biomass (40-58%), shoot biomass (46%), total N content (21-49%), and total P content (46-167%) compared to the control. The dual inoculation with H. seropediae and G. fasciculatum resulted in enhanced root length (15%), shoot length (40%), root biomass (105%), shoot biomass (91%), total N content (108%), and total P content (138%) compared to the control. Within the single inoculated plants, N accumulation was higher by 23% after H. seropedicae inoculation compared with G. fasciculatum inoculation. In contrast, P accumulation in plants was higher by 82% after G. fasciculatum inoculation compared with H. seropedicae inoculation. There was little difference in hyphal (92-95%) and vesicular (82-83%) infection between G. fasciculatum inoculated plants and G. fasciculatum + H. seropedicae inoculated plants indicating no interference of bacteria on mycorrhizal colonization in roots of S. bicolor