Effect of foliar application of Azospirillum brasilense and zinc sulfate on the grain-filling process of rainfed wheat

Grain growth (by weight), grain-filling rate, and the duration of each grain-filling phase are crucial in determining the final grain weight. Two experiments were conducted to evaluate the effects of ZnSO۴ on grain filling in the Sardari wheat cultivar. In the first experiment, the grain-filling rate and grain growth were assessed following foliar application of ZnSO۴. The second experiment explored the effects of foliar Azospirillum brasilense, applied either alone or combined with ZnSO۴, on grain-filling rate, grain growth, and the duration of both the lag phase and the linear phase of grain filling. Zinc sulfate was applied at a rate of ۳ kg ha-۱ at the anthesis stage, and only the main stem spike was used for assessing the grain-filling process. Richards equation was employed to simulate grain filling. The results indicated that, compared to foliar Azospirillum alone, Zn application was more effective in enhancing grain growth (by weight) and ۱۰۰۰-grain weight. Foliar application of ZnSO۴ significantly increased the grain-filling rate, and ZnSO۴, whether applied alone or combined with Azospirillum, extended the lag phase duration. Additionally, the ZnSO۴ + Azospirillum treatment sustained higher relative water content in the flag leaves. While the time to reach the maximum grain weight was shorter in untreated plants, ZnSO۴ combined with Azospirillum extended the lag phase and grain-filling rate. This combined treatment may benefit wheat production in semi-arid areas where soil drying during the grain-filling period often shortens this crucial phase.

کلیدواژه ها:

Foliar application ، Grain-filling process ، Rainfed ، Richards equation ، Thousand-grain weight ، Wheat