Hormo- and halo-priming induced biochemical changes improve post-storage vitality and seedling performance of sesame seeds under abiotic stresses
Abstract
Seed priming mitigates the negative effects of seed deterioration and abiotic stresses by increasing vigor with enhanced germination rate and percentage, as well as seedling growth. This study aimed to enhance the post-storage vitality of sesame by seed priming techniques and alleviate the detrimental effects of salinity, drought, and temperature stresses during germination and seedling growth stages. Seed priming techniques employed were halopriming (KCl 1.5%, CaCl 2 2%) , hormopriming (GA 3 50 mg kg −1 ), priming with MLE (3%), and hydropriming in comparison to untreated dry seed as a control. Primed and control sesame seeds were exposed to different salinity (0, 2.5, 5 dS m −1 ), water potential (0, −0.2, −0.4 MPa), and temperature (10, 20, 30, 40 °C) stresses during germination and seedling growth stages. Outcomes showed that incremental drought and salinity reduced the germination and seedling growth of post-storage sesame seeds. No germination occurred at 10°C, while maximum germination and seedling growth was found at 30°C with a simultaneous decrease at 40°C. Halopriming (KCl or CaCl 2 ) and hormopriming (GA 3 ) enhanced post-storage vigor of sesame seeds was attributed to increase in final germination and its rate, germination energy, and its index. The enhanced vigor also decreased the time to 50% germination (T 50 ) and mean germination time (MGT) under stress conditions. The post-priming improved vigor of sesame seeds was attributed to better membrane repairs owing to a decrease in seed leachates, MDA, and H 2 O 2 contents, as well as increased seedling fresh and dry weights under each stress type. A positive association of seed vigor with germination and seedling growth attributes was also found. In conclusion, halopriming (CaCl 2 or KCl) and hormopriming (GA 3 ) enhanced the post-storage vitality of sesame seeds and mitigated the detrimental effects of abiotic stresses during germination and seedling stages.