Perennial Forage Grasses Response to Deficit Irrigation as an Alternative for Water-Limited Conditions of Southern Chile

Perennial grasses are an important pasture forage source for the animal production industry around the world. However, the lack of available water limits the use and efficiency of the water resource for maximizing the forage yield. Furthermore, the highest perennial grasses production is obtained in southern Chile, where the frequency and intensity of the rainfalls has been significantly diminished in the main growing period. Thus, the purpose of this research was to evaluate the responses of forage yield (FY) and irrigation water use efficiency (IWUE) under different levels of water stress on perennial grasses sown in Chile. The experiment was conducted at the Regional Research Center Carillanca of the Instituto de Investigaciones Agropecuarias (INIA-Carillanca), Región de La Araucanía, Chile (38°41' LS; 72°24' LW; 188 m above sea level) during the 2017/2018 season. Four treatments of water stress were established: T1 (non-stressed: the soil moisture was always between readily available soil water and field capacity), T2 (80% irrigation application of T1), T3 (60% irrigation application of T1) and T4 (only rainfed). Seven perennial grasses were used: Chilean materials of Bromus valdivianus Phil (Bromino INIA, Bronco INIA, 3287 and 3771), Lolium perenne L. (Nui), Festuca arundinaceae Schreber (Kora) and Dactylis glomerata L. (Greenly). The soil water content at each water level condition was monitored using FDR sensors. The FY and IWUE were measured during all season, but in this study only shows data during maximum water demand period (January-February) reaching 2 cuts. Strip-plot statistical design with 7x4 factorial arrangements and three repetitions was used in this study. There were significant differences in FY and IWUE between perennial grasses and deficit irrigation condition. Some Bromus materials had the highest values of FY and IWUE, statistically similar to tall fescue Kora. These results are promising to find Chilean native perennial grasses materials that adapt better to water-limited conditions.