Plastic film mulch for half growing-season maximized WUE and yield of potato via moisture-temperature improvement in a semi-arid agroecosystem

► Examined effects of plastic mulch on soil moisture-temperature and yield for potato. ► Mulching get higher and earlier emergence rates by raising soil temperature-moisture. ► Mulching prolonged the duration from seedling to maturity and increased dry matter. ► Short mulching duration increased tuber bulk and WUE. ► Removing mulch at 65 days after sowing got high yield and WUE for potato. Effects of plastic mulching in ridges and furrows for varying durations on yield and water use efficiency (WUE) in potato were investigated in rainfed areas of north-western China in 2009 and 2010. The experiment comprised four mulched treatments (M50, M65, M80/85, and Mw – indicating plastic film mulch for 50, 65, and 80/85 d after sowing, and whole growth season, respectively – after which mulch in furrows was removed) and a non-mulched control. The results showed that film mulching warmed topsoil and increased topsoil water content. The daily mean topsoil temperature in mulched plots was 2.5–3.2 °C higher than that in controls during the early growing season (sowing–emergence), the difference became less as the plant canopy grew; on some days later in the season, the difference was even negative (i.e. the topsoil temperature in mulched was lower than in control plots). Seedlings under mulching emerged 8.1–11.7 d earlier than those in controls due to the increased topsoil temperature and moisture in the early season. Mulching also prolonged the duration from seedling to maturity by 0.7–15.0 d and significantly increased plant height, leaf area index, and dry matter. Compared to non-mulched plots, yields in mulched plots increased by 33.9–92.5% and 62.9–77.8% in 2009 and 2010, respectively, and corresponding WUEs improved by 41.4–112.6% and 45.9–70.6%. Both tuber yield and WUE were highest in M65. The data indicate that mulching for about 65 d after sowing was ideal to optimize soil moisture and soil temperature and in turn to improve potato productivity and WUE in this semi-arid rainfed region.