Influence of Foliar Application of Some Biostimulants on Physiological, Agronomic Characters and Crop Water Productivity of Rice Under Water Deficit and Normal Conditions

WATER deficit is a major environmental stress that has a tremendous effect on the physiological processes and productivity of rice. Thus, it is crucial to enhance rice tolerance to drought stress, especially under unpredictable climate changes and the increasing global population. This investigation aimed to study the impact of foliar-supplied nano-silica (Si-NPs) and potassium sulfate (K-sulphate) on some physiological, agronomic characters and crop water productivity of rice plants under water deficit and well-watered conditions during two summer seasons. The experimental design was a spilt-plot with four replications. The main plots were assigned to the two irrigation treatments; every 4 days (well-watered) and 12 days (water-deficit) after transplanting. The sub-plots were allocated by the three foliar treatments, namely, untreated control (distilled water application), foliar application of Si-NPs, and K-sulphate. The results displayed that the foliar applications, irrigation treatments, and their interactions had a significant influence on all the evaluated traits. Drought stress significantly reduced number of panicles per plant, number of grains per panicle, 1000-grain weight, and grain yield. However, water deficit considerably elevated antioxidant enzymes catalase (CAT) and peroxidase (POD) proline content compared to well-watered conditions. The foliar application of Si-NPs and K-sulphate was efficient in boosting drought tolerance by promoting antioxidant enzymes (CAT and POD) as well as proline accumulation compared with untreated plants. These positive influences were displayed in improving grain yield and its related traits as well as crop water productivity under drought stress conditions. Consequently, the utilization of foliar-applied Si-NPs and K-sulphate represents an applicable approach to enhance yield traits and crop water productivity of rice under water shortage conditions.