Physiological and Biochemical Effects of Thermo-Priming on Wheat (Triticum aestivum L.) under Drought and Heat Stresses

Abstract

Seed priming is a physical method for increasing the stress tolerance of crops against stressful environmental conditions. Drought and high temperatures are important environmental factors that limit the growth and grain yield of wheat. The aim of our study is to determine the physiological (germination rate, root and shoot length, specific leaf area (SLA), relative water content (RWC), biomass, total chlorophyll amount (SPAD)), and biochemical (protein amount, hydrogen peroxide (H2O2) amount, catalase activity (CAT), ascorbate peroxidase activity (APX), glutathione reductase activity (GR)) changes that occur with thermo-priming in wheat seeds under drought stress (D) and heat stress (H). Our results showed that shoot lengths were drastically reduced with D, H, and HD compared to root lengths. Besides, combined stress protected RWC by 6.8% with 60 min thermo-priming compared to other stress treatments. Chlorophyll content decreased dramatically with D and H, while thermo-priming wasn’t limited to that decrease. In addition, SLA was decreased with all stress treatments, while it healed only with 60 min thermo-priming (HDT60) by 12%. H2O2 was increased with drought stress, while reduced with all heat stress treatments. Among them, HDT60 was found to be more effective than the others. GR activities were increased with thermo-priming by 14-18%, with D and H by 5%. Additionally, GR activity was increased with 30 min thermo-priming (HDT30) in HD treatment by 5.8%, while only with HD by 3.2%. Consequently, HDT60 seemed to effectively on biochemical parameters in wheat seedlings against drought and heat stresses.