Physiological Role Of Salicylic Acid In Improving Performance, Yield And Some Biochemical Aspects Of Sunflower Plant Grown Under Newly Reclaimed Sandy Soil

Salicylic acid (SA) is an endogenous plant growth regulator, acting as non enzymatic antioxidant and has a regulatory effect on some physiological and biochemical processes. Therefore, this work was conducted during two successive summer seasons to evaluate the performance of two sunflower cultivars (Sakha 53 and Giza 102) to salicylic acid. The plants were grown at the experimental station of Agricultural Production and Research Station, National Research Centre, El Nubaria Province, El Behaira Governorate, Egypt. Sunflower seeds were soaked for 12 hours with different concentrations of SA (0, 25, 50, 75,100 mg/l) before sowing. It was noted that cultivation of Giza 102 performed well than Sakha 53 under sandy soil conditions. The obtained data revealed that, all treatments caused significant increases in growth parameters and photosynthetic pigments. The maximum increases in total pigments are 26.12% and 11.96% for Sakha 53 and Giza 102 cultivars at treatments 50 and 100 mg/l salicylic acid respectively. In addition, 75 and 100 mg/l salicylic acid were the most effective concentrations in increments of endogenous phytohormones i.e. IAA, GA3, zeatin and zeatin riboside as well as the most effective treatments in decreasing ABA for Sakha 53 and Giza 102 respectively. Significant increases in total carbohydrate and phenolic contents were obtained in shoots due to all treatments. Seed yield and components were increased significantly at all SA treatments. Since, the highest increases in seed yield (ton/fed) were 26.76 and 35.00% for Sakha 53 and Giza 102 at 75 and 100 mg/l salicylic acid respectively. All treatments caused significant increases in oil and protein % relative to those of the control. Meanwhile, a marked decrease in total saturated fatty acids accompanied by an increase in total unsaturated fatty acids was observed in both cultivars. Thus, SA treatments had regulatory effect on growth, seed yield, total carbohydrate, phenolic content and the quality of the oil in favour of the increase of unsaturated fatty acids of sunflower plant grown under newly reclaimed sandy soil.