Red clover is a very important species in temperate regions of Chile and around the world. Southern Chile has been affected by climate variability, particularly relating to the quantity, distribution, and frequency of rainfall patterns. Over time, this has changed the red clover persistence and dry matter (DM) yield. The study was conducted at the Regional Research Center Carillanca of the Instituto de Investigaciones Agropecuarias (INIA-Carillanca), Región de La Araucanía, Chile (38°41′ S, 72°25′ W, and its elevation is 188 m.a.s.l.) during the 2014/2015 and 2015/2016 growing seasons. The objective was to evaluate the response of red clover materials on dry matter yield, populations, and irrigation water use efficiency under deficit irrigation (DI) conditions. The irrigation treatments were: non-stressed (T1; irrigation application was supplied when the volumetric soil moisture content was close to 50% of total water available), 80% of T1 (T2), 60% of T1 (T3) and rainfed (T4) were imposed. Forage yield (FY), plant density (Src) and irrigation water use efficiency (IWUE) were measured. The highest total average forage yield was 27.5 and 24.6 t DM ha−1 for all evaluated irrigation treatments and red clover materials, respectively. The highest average value of plant population was above 30 plants m−2 at the end of the second season. IWUE was close to 2.6 kg DM m−3 during the periods of maximum atmospheric demand (from January to March) for both growing seasons. A reduction of 20% of the applied irrigation could be a viable alternative for saving water in southern Chile without significantly reducing forage yield.

中文翻译：

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红三叶草对亏缺灌溉的反应：智利南部的干物质产量、种群和灌溉用水效率

红三叶草是智利和世界各地温带地区非常重要的物种。智利南部受到气候变率的影响，特别是与降雨模式的数量、分布和频率有关。随着时间的推移，这改变了红三叶草的持久性和干物质 (DM) 产量。该研究是在智利拉阿劳卡尼亚地区（南纬 38°41′，西经 72°25′，海拔 188 masl）的 Instituto de Investigaciones Agropecuarias (INIA-Carillanca) 区域研究中心进行的。 2014/2015 和 2015/2016 生长季节。目的是评估红三叶草材料在亏缺灌溉 (DI) 条件下对干物质产量、种群和灌溉用水效率的响应。灌溉处理为：无压力（T1；当土壤体积含水量接近可用总水量的 50%)、T1 (T2) 的 80%、T1 (T3) 的 60% 和雨养 (T4) 时，提供灌溉应用。测量了牧草产量 (FY)、植物密度 (Src) 和灌溉用水效率 (IWUE)。对于所有评估的灌溉处理和红三叶草材料，最高总平均草料产量分别为 27.5 和 24.6 t DM ha-1。在第二季末，植物种群的最高平均值在 30 株 m−2 以上。在两个生长季节的最大大气需求期间（1 月至 3 月），IWUE 接近 2.6 kg DM m-3。减少 20% 的应用灌溉可能是智利南部节约用水的可行替代方案，而不会显着降低草料产量。