Effect of Different Levels of Tape Irrigation on Yield and Water Productivity of Tropical Alfalfa Cultivars

The present research was conducted to determine water stress tolerance and water productivity (WP) of 5 alfalfa cultivars as a split-plot design in a randomized complete block with 3 replications in the Safiabad Agriculture and Natural Resources Research Center (SARRC) with Silty clay loam soil texture during 2018-2019. The main plot was 4 levels of water irrigation depth (including 25, 50, 75, and 100% water requirement supply) with a constant irrigation cycle and the sub-plot was the five alfalfa cultivars (Baghdadi, Yazdi, Nikshahree, Omid, and Mesasirsa). Two-year data on forage yield and WP for six harvests (from June to November) were analyzed by SAS software. The results showed that the wet and dry forage yield decreased by applying water stress and the percentage of dry forage increased. The highest yield of dry matter (12.4 tons ha-1) and WP of dry forage (0.94 kg m-3) were obtained from 75% water requirement supply treatment. Baghdadi genotype with wet and dry forage yield 39.1 and 10.7 tons ha-1, respectively, and the WP of dry forage 0.9 kg m-3 was higher than other genotypes. However, the Yazdi genotype had the lowest yield of wet and dry forage (30.3 and 8.5 tons ha-1, respectively) and dry forage WP (0.75 kg m-3). Therefore, the Baghdadi genotype with a 75% water requirement supply is recommended for similar conditions to the climate of Northern Khuzestan to increase water productivity.