Response of red clover to deficit irrigation: dry matter yield, populations, and irrigation water use efficiency in southern Chile

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), Region de La Araucania, Chile (38 degrees 41 ' S, 72 degrees 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 (S-rc) and irrigation water use efficiency (I-WUE) 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.I(WUE)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.