Alkali stress limits plant growth and yield more strongly than salt stress and can lead to the appearance of yellow leaves; however, the reasons remain unclear. In this study, we found that (1) the down-regulation of coproporphyrinogen III oxidase, protoporphyrinogen oxidase, and Pheophorbide a oxygenase in oats under alkali stress contributes to the appearance of yellow leaves (as assessed by proteome and western blot analyses). (2) Some oat proteins that are involved in the antioxidant system, root growth, and jasmonic acid (JA) and indole-3-acetic acid (IAA) synthesis are up-regulated in response to alkalinity and help increase alkali tolerance. (3) We added exogenous spermine to oat plants to improve their alkali tolerance, which resulted in higher chlorophyll contents and plant dry weights than in plants subjected to alkaline stress alone. This was due to up-regulation of chitinase and proteins related to chloroplast structure, root growth, and the antioxidant system. Spermine addition increased sucrose utilization efficiency, and promoted carbohydrate export from leaves to roots to increase energy storage in roots. Spermine addition also increased the IAA and JA contents required for root growth.

To conduct ecological restoration in the Kubuqi sandy land and to select suitable superior Salix psammophila provenances, four provenances were selected from Dalate Banner, Ordos (DLT), Wushen Banner, Ordos (WSQ), Yulin, Shaanxi (YL), and Yanchi, Ningxia (YC). All cuttings were interplanted and established at an experimental site, and stumping was conducted five years after establishment. Six months after stumping, 11 parameters, including growth characteristics, gas exchange parameters, and photosynthetic pigments, were systematically measured. There were significant differences in plant height and branch number among Salix psammophila from different provenances, while there was no significance in the number of branches among different provenances. The daily variation in net photosynthetic rate (Pn) was significantly different among various Salix psammophila from different provenances, with highest in that from WSQ. The daily variations in stomatal conductance (Gs) and transpiration rate (Tr) from various provenances are relatively consistent, showing a unimodal trend. In terms of pigment content, the WSQ provenance exhibited the highest chlorophyll a content, while the YC provenance showed the highest carotenoid content. The variation coefficients of each parameters ranged 2.607–40.619%, with the highest for branch number, while the lowest for intercellular CO₂ concentration. Cluster analysis divided the Salix psammophila from four provenances into two groups, with DLT and YL being one group, and WSQ and YC being the other one. The results of entropy weight TOPSIS showed that the comprehensive ranking of various provenances was: WSQ > YC > YL > DLT, indicating the physiological properties of WSQ being superior to others, indicating its relatively high ecological adaptability in the semi-arid environment of the Kubuqi sandy land, and it can be used as a preferred provenance for ecological restoration and promotion applications.

Accurate estimation of soil hydraulic parameters under drip irrigation is essential for improving water flow simulations and optimizing irrigation management; however, field measurements in aeolian sandy soils are often expensive and time-consuming. This study focused on typical aeolian sandy soils in the Kubuqi Desert. Field drip irrigation experiments were conducted to obtain temporal variations in soil water content and wetting front advancement, which were used to inversely estimate and calibrate hydraulic parameters for different soil layers. Soil pore space characteristics were quantified using nitrogen adsorption, and their relationships with hydraulic parameters were analyzed through correlation and redundancy analyses. On this basis, the combined effects of particle-size distribution and pore space structure on parameter prediction were evaluated, and soil water movement under drip irrigation was simulated and validated using HYDRUS-2D/3D. The results indicated pronounced spatial variability in soil hydraulic parameters. Residual water content, saturated hydraulic conductivity, and pore-size distribution index were significantly correlated with specific surface area, total pore volume, mean pore diameter, micropore volume fraction, and pore fractal dimension. Compared with approaches based solely on particle-size distribution, incorporating pore space structure effectively reduced the prediction errors of both hydraulic parameters and wetting front migration, thereby improving simulation accuracy. These findings demonstrate that integrating particle-size distribution and pore space characteristics provides a feasible approach for the rapid estimation of hydraulic parameters and the analysis of water movement in aeolian sandy soils under drip irrigation.