Effect of deficit irrigation and within row spacing on morphological traits and grain yield of grain sorghum (Sorghum bicolor L. Moench) promising lines

To evaluate the effect of deficit irrigation and within row spacing on grain yield and yield components of grain sorghum promising lines, an experiment was conducted as split plot-factorial arrangement in randomized complete block design with three replications in 2015 and 2016 at the research field of Seed and Plant Improvement Institute, Karaj, Iran. Main plots consisted of three irrigation regimes (irrigation applied after 60, 120 and 180 mm cumulative evaporation from Class A pan) and sub-plots included factorial combination of three levels of within row spacing [8, 12 and 15 cm (21, 14 and 11 plant.m-2, respectively)] and three promising lines of grain sorghum (KGS23, KGS32, and KGS36). Combined analysis of variance showed that the sorghum prmising lines differed significantly for grain yield. The highest (5333 kg.ha-1) and lowest (4011 kg.ha-1) grain yield obtained from promising lines KGS23 and KGS32, respectively. The results showed that the response of the grain sorghum promising lines to the irrigation regimes was different, and KGS23 was significantly superior in comparison with the other two lines for most of the studied traits. In addition to high grain yield and desirable morphological traits, KGS23 showed adaptibility to deficit irrigation conditions. KGS36 ranked next to KGS23 for grain yield and tolerance to deficit irrigation. The effect of within row spacing on forage yield and biological yield was significant. Decreasing the within row spacing increased the forage and biological yields. Considering the stress tolerance (STI), geometric mean productivity (GMP) and grain yiled, KGS23 promising line which had higher grain yield in all irrigation regimes was identified as tolerant line with high grain yield.