Seed Priming Improves the Performance of Barley Under Drought Stress.

Drought stress leads to decline in plant growth and productivity by exerting effects on physiological and metabolic processes. A pot study was conducted to evaluate the potential of seed priming in improving the performance of barley under drought stress. Seed of two barley cultivars (Solum and Cochise) was subjected to hydropriming or osmopriming with 1.5% CaCl₂ solution; dry seed was used as control. After stand establishment drought was imposed at two levels i.e. well-watered (75% field capacity) and drought stress (40% field capacity). The results revealed that drought stress imposed deleterious effects on biosynthesis of total chlorophyll (Chl), rate of photosynthesis, transpiration, stomatal conductance, carboxylation use efficiency, quantum yield of photosystem II and electron transport rate (ETR) of barley. Total phenolics contents were initially decreased but afterwards exaggerated with continuous drought stress. Among both barley cultivars the Solum was photosynthetically more efficient and also produced higher phenolics contents than Cochise under both well-watered and water stressed conditions. Seed priming improved photosynthetic efficiency, quantum yield of photosystem II, ETR, and Chl and phenolics contents, and decreased the stomatal limitation, as compared to control. The improvement in the performance of barley by seed priming was in the order of hydropriming>osmopriming>control. In conclusion, seed priming improves the photosynthetic efficiency, quantum yield of photosystem II and ETR of barley under drought through improved biosynthesis of photosynthetic pigments, reduced stomatal limitation and improved protection of photosynthetic machinery by enhanced synthesis of phenolics. This research was partially supported by a Pakistan Higher Education Commission Fellowship to TT.