Phosphorus and dry matter accumulation and partitioning as affected by fertilizer phosphorus rate and inoculation by phosphate solubilizing bacteria in wheat and barley

Information on the concentration and accumulation of phosphorus (P) in the plant dry matter (DM) and the coefficients of its allocation to different plant parts can help improve the P nutrition of crops and increase the efficiency of P fertilizers. In order to investigate the effect of inoculation with Streptomyces sp. bacteria and fertilizer P rate (0, 20, 40, 60 and 80 kg P ha) on the P and DM accumulation and partitioning in wheat (cultivar Morvarid) and barley (cultivar Sahara), a factorial experiment in a completely randomized design with four replications was carried out in Gorgan University of Agricultural Sciences during 2014-2015 growing season. The amount of soil available P was 5.8 mg kg-1. Results showed that the effects of fertilizer P rate on DM accumulation, the P concentration and accumulation in all plant parts was significant (P = 0.01), statistically. Inoculation also influenced the DM accumulation in all parts except seeds, and P accumulation in all of them except the stem, but its effect on the P concentration in different parts of plant with the exception of leaf and root was not significant. As a result, it can be deduced that the rate of fertilizer phosphorus through both DM accumulation and P concentration, and inoculation only via DM accumulation affects the P accumulation. Also, the findings of this study showed a very high stability of allocation coefficients of DM and P to different parts of plant compared to DM and P accumulation and P concentration. P concentrations in the whole plant and grain in control (without P fertilizer) were 2.29 and 3.86 g P kg-1, and in the treatment of 80 kg P ha-1 were 3.89 and 6.00 g P kg-1. Also, the amount of accumulated P in a grain was 2.18 and 2.68 mg and in whole plant (shoot root) was 4.88 and 5.15 mg in wheat and barley, respectively. By increasing the rate of P fertilizer, accumulated phosphorus in all parts of the plant was increased linearly with different slopes, and reached to 6.98 and 9.08 at grain and 14.48 and 14.75 mg at whole plant of wheat and barley, respectively, when 80 kg P ha-1 was applied. The results showed a 197 and 186 percent increase in P uptake in wheat and barley, respectively, in the treatment of 80 kg P ha-1 compared to control. In both crops, at all levels of P fertilizer, the plant organs based on the amount of P accumulates were as seed > stem > leaf> root.