Evaluation of drought tolerance in fodder sorghum cultivars using stress sensitivity and tolerance indices

This experiment was conducted in order to evaluate the effect of water deficit irrigation on the agronomic characteristics of fodder sorghum cultivars in Kerman province. This experiment was carried out as a strip split-plot in a complete randomized block design with four replications in a research farm of agricultural research center of Jirof and Kahnooj, Kerman province, in 2019 and 2020. Drought stress as a vertical factor in four levels including without stress (irrigation after 80 mm evaporation from evaporation pan) as control, mild stress (irrigation after 110 mm evaporation from the evaporation pan), medium (irrigation after 140 mm evaporation) and sever (irrigation after 180 mm evaporation) and four sorghum cultivars including Spidfeed, Sugar graze, Jumbo and Pegah as a horizontal factor. The highest yield of fresh forage yield under non-stressed conditions (control) was observed in Spidfeed and Pegah (121.60 and 118.79 ton.ha-1, respectively). Also, Spidfeed and Pegah had the highest dry forage yield under non-stressed conditions (control) as 22.50 and 20.69 ton.ha-1, respectively. Also, the highest yield of dry forage in mild drought stress was observed in Pegah and Speedfeed varieties (15.30 and 14.88 ton.ha-1, respectively) and under medium drought stress in Pegah (11.12 ton.ha-1), whereas Spidfeed variety was superior to others for dry forage yield (7.42 ton.ha-1), in severe drought stress. Based on MP and STI indices, Spidfeed and Pegah cultivars with higher average of dry fodder yield were selected as the most suitable genotypes under drought stress conditions in Jiroft region of Kerman province.