Using Plastic Mulching Improves Greenhouse-Grown Pakchoi (Brassica rapa subsp. chinensis) Growth and Water Use Efficiency under Irrigation Scheduling Based on Soil Water Content

Scarce water resources limit protected vegetable production in North China. Implementing efficient water-saving techniques is crucial for maintaining protected vegetable production and sustainability. A two-growing season field experiment was conducted in a glass greenhouse to explore the effects of water-saving techniques with irrigation scheduling based on soil water content on the growth and quality of pakchoi and the fate of irrigation water. Three water-saving techniques were investigated: micro-irrigation (M-0), furrow irrigation with plastic mulch (F-P), and micro-irrigation with plastic mulch (M-P) compared to furrow irrigation (F-0). F-P and M-P treatments enhanced pakchoi growth and primarily increased the total root length of the root system (0-0.2 m) compared to F-0. The two treatments further induced an improvement of pakchoi quality. Compared to M-0, F-P and M-P treatments showed better performance in reducing evaporation by 57-70% and proportion of evaporation in evapotranspiration, and consequently exhibited more pronounced effects on water saving. Irrigation water use efficiency (IWUE) was improved in F-P by 50% in both seasons and was improved in M-P by 84 and 95% in spring season and autumn season, respectively. Combining irrigation scheduling based on soil water content with plastic mulch is a feasible way to improve IWUE in protected vegetable production by reducing water consumption and enhancing crop growth.