The Effect of Delayed Sowing and Application of Phosphate Solubilizing Bacteria on Dry Matter Accumulation and Remobilization in Bread Wheat Cultivars

In order to evaluate the ability of wheat cultivars to accumulate reserves in the stem and remobilization of these reserves to seeds under heat stress resulting from delayed sowing and to investigate the effect of phosphate-solubilizing bacteria on this ability, this study was carried out as split factorial based on a complete randomized block design with three replications in Haftkol, Khuzestan, Iran, in the growing season of 2016-2017. The main factor consisted of sowing date in two levels (22 November as conventional and 2 January as delayed seeding dates) and a factorial of the two subfactors consisting of five bread wheat cultivars (Chamran2, Mehregan, Sirvan, Shush and Barat) and two levels of application of phosphate solubilizing bacteria, Pseudomonas putida (P13) and Pantoea agglomerans (P5), (inoculation and without inoculation). The results showed that the reduction of stem specific weight (28.5%), stem length (18.7%) and effective grain filling duration (38.3%) were the most important reasons for reducing dry matter remobilization to stem and the efficiency of this remobilization in delayed sowing. At both sowing dates under bacterial seed inoculation conditions, the dry matter remobilization efficiency was 8.5% lower than the non-inoculated conditions. In the conventional sowing date, the relationship between spike weight and dry matter remobilization was positive and significant, but at delayed sowing date, spike weight and grain yield were not significantly related to dry matter remobilization and efficiency. In general, stem specific weight was recognized as the most important factor affecting the accumulation of reserves in the stem and Mehregan cultivar, with the ability to utilize stem reserves, was introduced as a suitable cultivar for delayed cultivation in the region.