Water restrictions on irrigation are rarely science based and may cause irreversible damage to turfgrass or inadvertently waste water. Our objectives were to evaluate effects of minimum water applications to ‘Meyer’ Japanese lawngrass (Zoysia japonica Steud.) on (a) canopy performance during prolonged drought and (b) survival and recovery thereafter. Meyer was watered weekly with 0–30% reference evapotranspiration (ET_o) replacement for ≥56 d in two consecutive summers under a rainout shelter near Manhattan, KS. Soil moisture and canopy performance (normalized difference vegetation index [NDVI], percentage green cover [PGC], and turfgrass quality) were measured weekly. Results indicated 20–30% ET_o slowed the decline in canopy performance compared with no water inputs. Irrigation at 30% ET_o maintained Meyer at >75% PGC throughout the first year, but even Meyer at 0 and 5% ET_o recovered after full irrigation resumed. In the second year, 30% ET_o maintained Meyer at >25% PGC throughout the drought and recovered thereafter, but plots with 0 and 5% ET_o only recovered to 30–42% PGC after 50 d of full irrigation. Depending on the weather, reducing irrigation from the recommended 60% ET_o for warm-season turfgrasses to 30% ET_o saved 9–11 cm of water; further reductions to 20% ET_o saved another 3–4 cm during the droughts of ≥56 d with insignificant additional PGC reductions (<18%). Water restrictions during severe droughts, such as limiting weekly irrigation of Meyer Japanese lawngrass to 20–30% ET_o, could reduce turfgrass damage and conserve water.

中文翻译：

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长期干旱期间日本草坪草生存的最低水要求

灌溉用水限制很少以科学为基础，可能会对草坪造成不可逆转的损害或无意中浪费水。我们的目标是评估对'Meyer'日本草坪草（Zoysia japonica Steud.）的最少浇水对（a）长期干旱期间的冠层性能和（b）此后的存活和恢复的影响。Meyer 在堪萨斯州曼哈顿附近的一个雨棚下连续两个夏天每周浇水 0-30% 的参考蒸发量 (ET _o ) 替代 ≥ 56 天。每周测量土壤水分和冠层性能（归一化差异植被指数 [NDVI]、绿色覆盖百分比 [PGC] 和草坪质量）。结果表明 20–30% ET _o与没有水输入相比，减缓了树冠性能的下降。在整个第一年，30% ET _{o 的}灌溉使 Meyer 保持在 >75% PGC，但即使是 0 和 5% ET _{o 的}Meyer 在恢复完全灌溉后也恢复了。在第二年，30% ET _o在整个干旱期间将 Meyer 保持在 >25% PGC 并在此后恢复，但具有 0 和 5% ET _{o 的}地块在充分灌溉 50 天后仅恢复到 30-42% PGC。根据天气情况，将暖季型草坪草的灌溉量从推荐的 60% ET _o减少到 30% ET _{o 可}节省 9-11 厘米的水；进一步减少到 20% ET _o在 ≥ 56 天的干旱期间又节省了 3-4 厘米，而 PGC 的额外减少（<18%）微不足道。严重干旱期间的用水限制，例如将 Meyer 日本草坪草的每周灌溉限制为 20-30% ET _o，可以减少草坪草的损害并节约用水。