Effect of Salicylic Acid on Photosynthetic Activity and Performance Flowers Borage Plant (Borago officinalis)

Background: Medical plants production, including borago, is for maximum productivity from their effective ingredients’. Flowers, leaves and seed oil are medical parts of borago. Unfortunately, because of little breeding and domestication programs in medical plants, including borago, their establishments are usually slow. One of the effective techniques for solving this problem is seed priming. Salicylic acid is a plant hormone which improves growth and yield under different environmental conditions. Objective: This experiment was done for founding the best method and concentration on photosynthetic properties of borago. Methods: For studding the effect of salicylic acid on some photosynthetic properties of borage plants (stomatal conductance, transpiration rate, internal CO2 concentration, carboxylation efficiency and chlorophyll index) an experiment was done in randomized complete design with three replications. Treatments include borago seeds priming by four concentrations of salicylic acid (500, 1000, 1500 and 2000 µM), plants spraying in two stages with four concentrations of salicylic acid (500, 1000, 1500 and 2000 µM), priming seeds with distilled water (hydropriming) and dry or control seeds. Results and Conclusion: Results showed that priming with salicylic acid and especially spraying with salicylic acid in 1500 µM had significant effect on photosynthesis and photosynthetic indexes, and finally increased flowers dry weight. The most photosynthetic activity, stomata conductance, transpiration rate, carboxylation efficiency, the lowest internal CO2 concentration were found in spraying with 1500 and priming with 500 µM SA. In addition, the highest chlorophyll index was found in spraying with 2000 µM and priming by 500 µM SA. On the other hand, any treatment by SA had not any significant effects on basic water use efficiency (WUEb). It seems that treating plants by SA by any ways leads to increasing plants performance compared to untreated seed or plants, even hydroprimed seeds.