Physiological Mechanism of Exogenous Silicon Alleviating Drought Stress in Maize

Abstract

With the global warming, the impact of drought on agricultural production is increasingly prominent. Maize has a long growth period, high water demand, and is more sensitive to drought. Therefore, drought has always been one of the limited factors affecting the stable and increased on global maize production. Si promotes seed germination and seedling growth, enhances agricultural sustainability. However, its effects on different growth stages and different drought degree of maize are unclear in the field. In this experiment, to study its effects of drought in the large farmland moisture control test field (Xianyu 335) combined with exogenous Si during growth and development in maize. Exposed to drought-stressed conditions, Si further aggrandized antioxidant enzyme activities, reduced ROS contents, not only moderated AsA/DHA ratio but also GSH/GSSG ratio. Adding exogenous Si, the plant height growth rate, biomass, photosynthetic pigment contents, gas exchange parameters, photosynthetic enzymes activity, the stomatal size and aperture improved significantly, the contents of osmolyte further increased, as well as the increases were greater in the jointing stage than in the tasseling stage. In summary, applying exogenous Si can enhance the photosynthesis capacity of plants, promote the synthesis of osmotic substances, thus improving plant water metabolism balance, and enhance the antioxidant system, remove toxic substances, reduce membrane peroxidation, maintain cell membrane stability, alleviate stomatal limitation, and enhance maize drought resistance of the plant, thereby increasing yield.