Deficit irrigation and double mulching for water saving, high yield and quality of kiwifruit in Shaanxi Guanzhong areas of China

To investigate the issue of seasonal water scarcity limiting the growth of kiwifruit in the Guanzhong Plain of Shaanxi Province and to propose optimal irrigation amounts and mulching measures, this study conducted an experiment using kiwifruit as the subject. The experiment included three irrigation gradients: W1 (irrigation upper limit of 85% θf, where θf is the field capacity), W2 (75% of W1), and W3 (60% of W1), additionally, four ground mulching were implemented: FG, FN, NG, and NN (F: intra-row horticultural fabric mulching, G: inter-row grass mulching, N: clean tillage), resulting in a total of 12 treatments. Through two years of field experiments, the soil water storage, kiwifruit growth, yield and quality were analyzed. The results showed that F mulching significantly increased intra-row soil water storage under the W1 treatment, while G mulching significantly enhanced inter-row soil water storage under the W2 treatment (P < 0.05). The FG treatment increased intra-row soil water storage by 2.21–42.23 mm while maintaining inter-row water storage. The FGW2 treatment improved photosynthetic parameters (Pn, Tr, and Gs) during the fruit expansion to maturation stages, increasing single fruit weight by 30.38%, yield per plant by 76.38%, and soluble sugar and soluble solid content by 15.15% and 44.26%, respectively (P < 0.05). The FGW1 treatment significantly reduced the organic acid content by 19.70% and increased the sugar-to-acid ratio by 37.75% (P < 0.05). The combination of mulching and irrigation influenced leaf photosynthesis during critical growth stages by enhancing soil water storage, thereby improving yield and quality. Among them, the soil water storage during the fruit expansion stage was most closely related to kiwifruit growth, yield, and quality. In the Guanzhong region, adopting FG mulching combined with W2 irrigation can effectively improve soil water storage and photosynthetic efficiency of kiwifruit orchards, ensuring yield and enhancing fruit quality, providing a feasible measures for kiwifruit production.