Post-anthesis drought stress: impacts on seed filling and translocation in safflower cultivars

Abstract

During whole plant senescence induced by drought stress, plants mobilize assimilates stored in vegetative reserves to support seed development. This study aimed to evaluate the contributions of vegetative reserves to seed development under drought conditions simulated using chemical desiccant and to identify drought-resistant safflower (Carthamus tinctorius L.) cultivars. The study was conducted under field conditions in a semi-arid region of Türkiye using nine safflower cultivars. Drought stress was induced by applying potassium chlorate to the plants during the post-flowering period. Significant differences were observed among cultivars in their capacity to translocate reserve photosynthetic assimilates and in their responses to post-anthesis drought stress. The results indicated that the Dinçer and Linas cultivars exhibited high leaf SPAD values (36.47–53.86), leaf temperatures (23.40–25.22°C), and relative water content (54.17–72.71%). The Balcı cultivar exhibited high dry matter translocation (2.76–10.10 mg seed⁻¹), dry matter translocation efficiency (16.37–51.95%), whereas the Safir cultivar showed high oil content under control conditions (32.76–39.19%), and oil content under stress conditions (18.25–25.25%). The Hasankendi cultivar had a high grain weight reduction (23.33–49.22%). The Linas cultivar demonstrated high mean productivity (101–162 kg da⁻¹), while the Olas and Yekta cultivars exhibited high seed yield tolerance (34.9–71.4 kg da⁻¹). According to the results, post-anthesis assimilate storage is an important indicator for the selection of drought-tolerant safflower genotypes.