Effect of soil conditioner on alleviating saline-alkali stress damage of maize

Soil conditioners are efficacy in ameliorating saline-alkali soils and fostering crop growth. To explore the effect and physiological mechanism of soil conditioner on improving the adaptability of maize to saline-alkali stress, we conducted a field randomized block experiment in Liuzhong Village, Pingluo County, Ningxia Province in 2022. We investigated the variations of antioxidant capacity, key enzyme activities and photosynthetic fluorescence properties of maize induced by soil conditioners under saline-alkali stress, with "Xianyu 1255" maize as the experimental material under four treatments: T₀(no conditioner, control), T₁(humic acid), T₂(microsilica fume + wood vine-gar solution), T₃(humic acid + wood vinegar solution + microsilica fume). The results showed that soil conditioner could enhance the antioxidant capacity, key enzyme activity and photosynthetic fluorescence characteristics of maize leaves. The superoxide anion scavenging rate and superoxide dismutase activity of each treatment in the two growth stages (jointing stage-big flare stage and grain filling stage) were significantly increased and the content of malon-dialdehyde was significantly decreased. The aquaporin activity of each treatment in the jointing stage-big flare stage was significantly enhanced. Transpiration rate, net photosynthetic rate, stomatal conductance, non-photochemical quenching coefficient, apparent synthetic electron transfer rate and actual photochemical efficiency were significantly enhanced, while the intercellular carbon dioxide concentration was significantly decreased in T₂ and T₃ treatments. The hydroxyl radical scavenging rate and initial fluorescence of each treatment were significantly increased in each treatment at the grain filling stage. T₃ performed the best. Structural equation modeling and membership function analysis confirmed that soil conditioners could bolster the antioxidant system and aquaporin activity in maize, mitigate membrane lipid peroxidation, enhance stomatal conductance, and improve photosynthesis, thereby improve the resistance of maize to saline-alkali. The combined application of humic acid, wood vinegar, and microsilica fume was the most effective one.