Irrigation Quantity and Frequency Influence Canopy Development and Yield Stability in Potato under High-Temperature Conditions

Abstract Potato ( Solanum tuberosum L.) production is expanding in subtropical environments where heat and irregular rainfall constrain yield. This study investigated how seasonal water input patterns and dry spells affect potato growth, yield, and quality when high temperatures occur early and late in the season. We conducted a three-year field experiment in Gujarat (India) in which we compared two irrigation quantities (full, maintaining the topsoil near field capacity; and reduced, at 80% of the ‘full’ volume) combined with three dry spell treatments (none, short, and long). The treatments aimed to simulate variation in the seasonal water input and its temporal distribution. Reduced irrigation consistently decreased fresh and marketable yield across seasons by 16–23%. It also shifted the tuber size distribution towards smaller tubers. Reduced irrigation slightly increased tuber dry matter content. Long dry spells clearly reduced leaf expansion, but their effects on canopy duration, seasonal light interception and yield were season-dependent. Across seasons, reduced irrigation without dry spells produced similar outcomes to full irrigation with long dry spells. No significant interaction between irrigation quantity and dry spells was observed. These results show that reduced seasonal water input and prolonged soil drying (e.g., through climate change) can jointly reduce potato yield and marketable size in the studied region. Frequent (at least every six days) and low-dose irrigation offers a practical route to maintain water productivity and tuber quality when water supply is limited.