the effect of pgpr and alfalfa extract on macronutrient and micronutrient contents of sorghum (sorghum vulgare)

The increasing population and the pastures inability to meet food needs in livestock have led to the increase of cultivates forage plants. in order to evaluate the effect of plant growth promoting rhizobacteria (pgpr) and alfalfa (medicago sativa) extract on the growth and concentration of macronutrient and micronutrient contents of  forage sorghum (sorghum vulgare), an experiment was conducted as factorial aaraned in a completely randomized design with six replications  at research greenhouse university of zabol. the first factor was pgpr (included soil inoculated and noninoculated (control) medium, and the second factor was alfalfa extract in three concentrations (0, 2 and 4 ppm). the results showed that increasing alfalfa extract concentration significantly increased total plant dry weight as well as the macro and micronutrient contents. the highest and lowest manganese contents were achieved in the 0.004 levels and control of alfalfa extracts, respectively. copper content in 0.002 level of alfalfa extract showed a 15% increase compared to the control, with no significant difference with 0.004 of alfalfa extracts. pgpr application as growing substrate also significantly increased dry weight as well as manganese, copper and potassium contents of the plant. also, there was no significant difference in iron content at level 4 per thousand of alfalfa extract in a substrate inoculated with pgpr compared to the noninoculated substrate. finally, it is recommended that the effect of alfalfa extract on yield and nutrient concentrations of other plants be examined in the future.