[Effects of water-saving irrigation on seedling growth, stomatal characteristics and photosynthetic properties of maize in secondary salinized cultivated land].

To clarify the alleviating effect of different water-saving irrigations at the seedling stage of maize under salt stress in arid irrigation area, we used 'Xianyu 1225' maize as the test material, and set up three irrigation treatments (T1, T2, and T3) in the salinized land in the Yellow River irrigation area. T1 treatment was the surface furrow irrigation at the sowing stage and three-leaf stage (T1, irrigation amount was 65 mm at both stages). Both T2 and T3 treatments were furrow irrigation at the sowing stage and drip irrigation at three-leaf stage (the irrigation amount at the sowing stage was 65 mm, and the irrigation amount at the three-leaf stage was 39 and 52 mm, respectively). The control (CK) was furrow irrigation at the sowing stage and the three-leaf stage in non-salinized land (irrigation amount was 65 mm at both stages). We investigated the effects of water-saving irrigation on leaf morphology, photosynthetic physiology, photosynthetic tissue structure and leaf fluorescence characteristics of maize seedlings under salinity stress. The results showed that furrow irrigation combined with drip irrigation could effectively reduced soil salt content and weakened soil salinity returning to the 0-20 cm soil layer of salinized land. Compared with CK, different irrigation treatments significantly changed the morphology, reduced antioxidant enzyme activities, stomatal structure, photosynthetic pigment content, photosynthetic fluorescence performance of maize leaves under salinity stress. Such decreases were the largest under the T1 treatment, and were relieved under T2 and T3 treatments. Furthermore, T3 treatment differed little in the antioxidant enzyme activities, net photosynthetic rate, transpiration rate, effective photochemical efficiency of maize leaves compared to CK. According to the results of structural equation model analysis, the water-saving irrigation increased the maximum photochemical efficiency of maize and alleviated the inhibition of salt stress on maize growth at seedling stage by reducing the Na⁺ content of plants, protecting the photosynthetic tissue and adjusting the proportion of photosynthetic pigments. In conclusion, the T3 mode was the best irrigation strategy in the study area.