Effects of different mulching practices on soil hydrothermal conditions and productivity of rainfed apple orchards in the Western Loess Region of Shanxi, China

Mulching techniques has been extensively applied in rain-fed agricultural systems to optimize crop productivity by enhancing soil hydrothermal conditions and plant physiological performance. A two-year field experiment was conducted in the western Loess Plateau of Shanxi in 2023 and 2024, which included seven mulching methods: 10 cm-thickness maize straw mulching (SM 10), 15 cm-thickness maize straw mulching (SM 15), 20 cm-thickness maize straw mulching (SM 20), horticultural fabric mulching (FM), black plastic mulching (BM), white plastic mulching (WM), and a non-mulched control (CK). The results showed that six mulching treatments improved soil water content (SWC) during the whole growth season, with FM and SM 15 showing the greatest increases of 18.1% and 23.8%, respectively. Straw mulching reduced soil temperature, whereas FM buffered temperature fluctuations and plastic mulches increased soil temperature. Soil water had strongest effect on leaf photosynthetic rate (direct path coefficient = 0.47). FM achieved the highest yield in both years. During the fruit enlargement stage, the photosynthetic rate of FM was 26.4% higher than that of CK, ultimately increased the yield by 8.7%. Overall, FM optimized soil hydrothermal conditions, enhanced tree physiology, and improved yield in rain-fed areas. • Mulching improved apple tree growth and increased yield by affecting soil moisture and temperature conditions. • Straw mulching decreased soil temperature, whereas horticultural fabric mulching (FM) buffered temperature fluctuations. • Path analysis shows that soil moisture is a direct factor influencing photosynthetic performance and can also indirectly enhance photosynthetic efficiency by improving canopy structure and growth status.