Effect of Early and Late Season Drought Stress on Agronomic Characteristics, Seed and Oil Yield of Safflower (Carthamus tinctorius L.) Genotypes in Marginal and Saline Soils around Lake Urmia

The aim of this study was to evaluate the effect of early and late season drought stress on autumn sown safflower genotypes in marginal and saline soils around Lake Urmia in East Azarbaijan in Iran. A filed experiment was carried out as split-plot arrangements in randomized complete block design with three replications at Khosroshah agricultural research field station, East Azarbaijan agriculture and natural resources research and education center, Tabriz, Iran, in 2019-20 and 2020-21 cropping seasons. Experimental factors included: drought stress levels (non-stress, drought stress in rosette stage and drought stress in seed filling stage) and safflower genotypes (cv. Padideh, cv. Golemehr, cv. Parnian, and Mexico14 and Mexico248 promising lines). The irrigation (water with EC = 4.2 ds m-1) of non-stressed plots was applied at the 80 mm and stressed plots at 180 mm evaporation from the Class A evaporation pan. The results showed that the effect of drought stress in the rosette stage on seed and oil yield was not significant. However, drought stress in the seed filling stage significantly decreased the seed no. head-1 by 17%, 1000-seed weight by 7%, and seed and oil yield by 48% and 51%, respectively. Therefore, application of irrigation in seed filling stage of safflower crop is necessary. The effect of drought stress on leaf relative water content and canopy temperature indices was significant, and these two indices were suitable for evaluation of drought sterss effect on safflower genotypes. It was concluded that cv. Padideh, cv. Golemehr, and Mexico248 promising line with 1983, 1979 and 2087 kg h-1 seed yield, respectively, under drought stress conditions in the seed filling stage, were adapted and suitable for being grown under late season drought stress in marginal and saline soils around Lake Urmia.