The Influence of Growth-Promoting Bacteria and Salicylic Acid on Leaf Area Index, Grain Yield and Harvest Index of Corn (Zea mays L.) under Non-irrigation Conditions at Different Growth Stages

Salicylic acid exerts significant effects on plant morph physiology, playing a pivotal role in stimulating protective mechanisms and enhancing resistance against both biotic and abiotic stresses. Current research was done to assess effect of biofertilizers and salicylic acid under non-irrigation conditions at different growth stages at corn crop production. The study was done as a split-plot experiment, using Randomized Complete Block Design (RCBD) with three replications. The main plots consisted of different irrigation conditions at various growth stages (including full irrigation (control), non-irrigation from the flowering stage to the end of the growth period and non-irrigation from the beginning of the grain filling stage to the end of the growth period) and various combinations of biological fertilizers and salicylic acid treatments were implemented in the sub-plots (including the control treatment, 1 mM salicylic acid, nitroxin + biophosphorus bacteria grain rub and nitroxin + biophosphorus bacteria grain rub along with salicylic acid spraying). The results indicated significant effects of irrigation treatments, biological fertilizers and salicylic acid, as well as their interactions, on leaf area index, yield and yield components. Non-irrigation from the flowering stage resulted in a substantial 58.3% reduction in grain yield compared to the control. However, the combined application of biological fertilizers and salicylic acid, under both non-irrigation and full irrigation conditions, led to a noteworthy increase in yield and yield components. In the non-irrigation treatment starting from the flowering stage and grain filling stages, the application of nitroxin + biophosphorus + salicylic acid bacteria treatment resulted in a significant increase in grain yield by 22.7% and 19.3%, respectively, compared to the control treatment. Moreover, the highest grain yield (with an average of 6552 kg.ha-1) was achieved through the combined effect of full irrigation and nitroxin + biophosphorus + salicylic acid foliar application. The application of non-irrigation during the grain filling stage, along with the combined use of nitroxin + biophosphorus grain treatment and salicylic acid foliar application, not only provided optimal conditions for the corn plant but also effectively mitigated the adverse effects of drought stress, resulting in yields equivalent to those achieved under normal irrigation conditions.