| Resumo: |
Ascobin had a promotion effect on growth and active constituents’ compounds of various plants under normal and stressed conditions. The physiological response of sunflower plant to foliar application of ascobin treatments (200,400,600 ppm) was investigated either under normal or salinity stressed conditions (5000 ppm NaCl solution) in pot experiments at the wire-house of the National Research Centre, Dokki, Cairo, Egypt. Data revealed that salinity stress caused significant decreases in shoot height, leaf area chlrorophyll b, carotenoids, total photosynthetic pigments, seed yield, yield components, oil and protein content of the yielded seeds relative to control. The decrease in oil percentage was more obvious by salinity than protein percentage. Since salinity caused decreases in oil % by10.42% and decreases in protein % by 3.44% relative to control. Meanwhile, salinity stress caused significant increases in H2O2, MDA and activity of antioxidant enzymes (CAT, SOD, APX and GR) as well as total soluble carbohydrate, phenolic content, proline, free amino acids. Salinity stress caused significant increases in sum of stearic acid and palmitic acid accompanied by significant decreases in sum of oleic and linoleic acids as well as ratio of oleic/linoleic and total unsaturated fatty acids/total saturated fatty acids. On the other hand, ascobin treatments caused significant increases in most of growth parameters and activity of all antioxidant enzymes under investigation accompanied by significant decreases in H2O2 and MDA under normal and stressed conditions relative to corresponding controls. Ascobin treatment at 400 ppm showed significant increases in all components of photosynthetic pigments under normal condition relative to control. Meanwhile ascobin treatments significantly decreased total soluble carbohydrate, phenolic content and increased proline and free amino acids. It was noted that all treatments alleviate the harmful effect of salinity stress on sunflower yield and yield components. Since all treatments caused significant increases in yield and yield components as well as oil and protein percentages. Ascobin treatment at 400 ppm was the most optimum treatments in increasing seed yield/plant by 44.78% under normal condition and by 45.43% under stressed conditions relative to corresponding controls. Oleic acid and linoleic acid significantly increased by ascobin treatment at 400 ppm leading to non-significant decrease in total saturated fatty acid and significant increase in total unsaturated fatty acids.
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