Abstract: To explore the effects of different modified materials and their combined applications on the morphological characteristics of maize at seedling stage, an experiment was conducted on the saline-alkali land in Hetao Plain of Inner Mongolia. There were eight treatments, including control (CK), desulfurized gypsum (T1), soil ameliorant (T2), organic fertilizer (T3), desulfurized gypsum combined with soil ameliorant (T4), desulfurized gypsum combined with organic fertilizer (T5), soil ameliorant combined with organic fertilizer (T6), and desulfurized gypsum combined with soil ameliorant and organic fertilizer (T7). We measured plant height, photosynthetic rate and root morphological characteristics of maize seedlings. The results showed that: (1) the T7 treatment had the strongest promoting effect on plant height, stem diameter and SPAD value, with an increase of 30.0%, 24.2% and 27.8%, respectively. (2) The combined treatments significantly increased net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and leaf water use efficiency, but significantly decreased transpiration rate. The combined treatments had a better promoting effect on root morphological characteristics (total root length, surface area, number, volume) than the single treatments, with a significant increase in root branching and a significant increase in the number of lateral roots and root hairs with a diameter less than 1 mm. (3) Principal component analysis showed that the scores of maize photosynthetic performance and root morphological characteristics for different treatments were T7>T4>T6>T5>T2>T3>T1>CK. In conclusion, compared with single application and combined applications of two modified materials, the combined application of three modified materials had a stronger promoting effect on leaf photosynthetic capacity and root morphological characteristics of maize seedlings.

Key words: soil amelioration, photosynthesis, saline-alkali land, maize, root system