Effects of different water treatments on the growth, physiological, photosynthesis, and yield of potato under drip irrigation with plastic mulch in northwest China

Water scarcity has been a persistent challenge impeding the progress of the potato industry in northwest China. This field study was conducted in the arid and semi-arid regions of northwest China, specifically in Dingxi, Gansu Province, during the years 2018 and 2019, within a rain exclusion shelter. The 'Hermes' potato variety was selected as the experimental material. According to different field water capacity (FWC), six treatments were set, FWC85% was 85 %similar to 95 %, FWC75% was 75 similar to 85 %, FWC65% was 65 %similar to 75 %, FWC55% was 55 %similar to 65 %, FWC45% was 45 %similar to 55 %, and NI was no irrigation. The experimental setup involved a combination of ridging, film mulching, and drip irrigation to investigate the impacts of different FWC levels on growth characteristics, physiological traits, photosynthetic attributes, tuber yield, and water use efficiency (WUE). The results highlighted that maintaining an FWC above 65 % significantly enhanced plant height, stem diameter, number of branches, leaf area, dry matter accumulation, and tuber yield. Notably, the FWC75% treatment exhibited the highest levels of dry matter accumulation and tuber yield, showing increments of 235.87 %similar to 312.72 % and 198.99 %similar to 257.61 %, respectively, compared to the no-irrigation treatment. Analysis of physiological and photosynthetic characteristics indicated that an FWC range of 55 %similar to 65 % marks a critical threshold where the limiting factor for the net photosynthetic rate shifts from stomatal to non-stomatal. Water use efficiency (WUE) declined with increasing FWC, while irrigation water use efficiency (IWUE) initially rose and then declined with FWC increments. The FWC65% treatment stimulated potato root growth, enhanced water absorption in 40 similar to 80 cm soil depths, and effectively boosted IWUE. In summary, maintaining an FWC above 65 % proves pivotal for optimizing potato yield in the semi-arid conditions of northwest China, with the most favorable tuber yield observed at FWC levels of 75 %similar to 85 %. This study seeks to provide a theoretical foundation and technical backing for enhancing water-efficient potato cultivation practices in northwest China.