Ecophysiological and Agronomic Responses of Safflower Fall Genotypes under Drought Stress in Plant Settlement and Seed Filling Stages

In order to consider some echo-physiological responses related to the productivity of safflower fall genotypes to drought stress at plant greening, establishment, and seed filling stages and to recognize drought-tolerant genotypes, the present study was done.

An experiment was conducted as a split-plot based on a randomized complete blocks design with three replications in the Khosrow Shah station of East Azarbaijan Agriculture and Natural Resources Research and Education Center during the 2019-20 cropping season. The experimental factors included drought stress (non-stressed and stressed during plant greening and the establishment and seed filling stages, and five safflower genotypes including Padideh, Golemehr, Parnian, Mexico248, and Mexico14.

Occurring drought stress at the seed filling stage significantly decreased chlorophyll concentration, stomatal conductance, relative water content, seed and oil yields, and seed yield components in fall genotypes of safflower. Correlation among mentioned indices echo-physiological indices with each other and with seed and oil yields were positive and significant. Also, the amounts of mentioned indices among studied genotypes were significantly different.

The seed filling period of fall genotypes of safflower was critical for water requirements. Chlorophyll concentration, stomatal conductance, relative water content indices were able to reflect the drought stress effect during the seed filling period and can recognize the fall genotypes of safflower with high seed and oil yields under drought conditions. It seems that these echo-physiological indices are suitable to select late-season drought-tolerant safflower genotypes.