Abstract Partial rootzone drying (PRD) is an irrigation technique that usually applies less water (than well-watered control treatments) to only part of the rootzone (the irrigated side) and alternates the irrigated and non-irrigated sides. However, an incomplete understanding of the effects of its components (decreased water application versus frequency of alternating the irrigated side) on physiological responses of fruit crops such as papaya, is considered to be a constraint for its adoption under semiarid conditions. Therefore, a study was performed to determine effects of PRD on soil water dynamics, leaf gas exchange, yield, water use efficiency and water footprint in field-grown papaya. Yields and physiological measurements were evaluated under control (Full Irrigation - FI) and restricted (50 % and 35 % reduction in irrigation water depth - IWD) irrigation with the irrigated side alternated every 0, 7, 14 and 21 days. A drip irrigation system with three emitters on each side of the plant was used to apply surface drip irrigation as needed to supplement natural rainfall during the study period. Physiological functions, including stomatal conductance (gs), transpiration (E) and net photosynthesis (A) did not differ among treatments, but resultant differences in plant height and diameter growth rates were found to be significantly and positively related to yield. Decreasing the irrigation applied at moderate alternate frequency (PRD7 35 % and PRD14 35 %) increased agronomic water use efficiency of papaya (AWUE) without compromising its yield and gas exchange. Therefore, PRD strategy with irrigated side alternation frequency of every 7–14 days with a 35 % reduction in the irrigation depth could become a viable technique to reduce the water footprint of papaya, thus increasing the effective use of water under semiarid conditions.

中文翻译：

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田间木瓜的部分根区干燥：气体交换、产量和水分利用效率

摘要 部分根区干燥 (PRD) 是一种灌溉技术，通常仅向部分根区（灌溉侧）施用较少的水（比灌溉充足的控制处理），并在灌溉侧和非灌溉侧交替使用。然而，对其组成部分（减少浇水与交替灌溉侧的频率）对木瓜等水果作物生理反应的影响的不完全了解被认为是其在半干旱条件下采用的一个制约因素。因此，进行了一项研究，以确定 PRD 对田间种植的木瓜的土壤水动力学、叶气交换、产量、水分利用效率和水足迹的影响。在控制（完全灌溉 - FI）和限制（灌溉水深减少 50 % 和 35 % - IWD）灌溉下评估产量和生理测量，灌溉侧每 0、7、14 和 21 天交替。在研究期间，植物每侧具有三个发射器的滴灌系统用于根据需要应用地面滴灌以补充自然降雨。生理功能，包括气孔导度 (gs)、蒸腾作用 (E) 和净光合作用 (A) 在处理之间没有差异，但发现植物高度和直径生长速率的结果差异与产量显着正相关。减少以中等交替频率（PRD7 35 % 和 PRD14 35 %）施用的灌溉可提高木瓜的农艺用水效率 (AWUE)，而不会影响其产量和气体交换。因此，每 7-14 天轮流灌溉一次、灌溉深度减少 35% 的珠江三角洲策略可能成为减少木瓜水足迹的可行技术，从而增加半干旱条件下水的有效利用。