Mitigation of adverse effects of salinity stress on sunflower plant (Helianthus annuus L.) by exogenous application of chitosan

Abstract

Abstract Background Most developing countries are suffering from a decline in agricultural area and fresh water supply due to the adverse effects of climate change. Sunflower has been considered as having the ability to grow under various environmental conditions, tolerating levels considered stresses to other plants. Materials and Methods Thus, two field experiments were conducted in the screen of National Research Centre during two successive summer seasons 2018 and 2019, respectively to investigate the effect of soaking seeds of sunflower plant in different concentrations of chitosan (control, 25, 50 and 75 mg/L) on growth, some physiological parameters, yield and its components and some chemical composition of the yielded seeds of sunflower under different salinity levels (control, 4000 and 8000 mg/l). Results The obtained results showed that salt stress with 4000 mg/L recorded the highest values of all the studied growth characters, photosynthetic pigments, some physiological aspects, seed yield/plant and oil %. On the other hand, the highest values of head diameter, head circumference, weight 50 seed and crude protein were obtained by control treatment. Meanwhile, the highest values of proline and free amino acid were recorded under higher salinity level (8000 mg/L). On the other hand, all chitosan treatments significantly enhanced growth and productivity of sunflower plant. Also, the obtained data that, chitosan concentration (50 mg/L) recorded the highest values of all the studied growth and yield quantity and quality via enhancing photosynthetic pigments and the studied physiological aspects, as compared with other treatments. As for interaction effect, plants treated with chitosan concentration (50 mg/L) under salinity level (4000 mg/L) recorded the highest growth characters, photosynthetic pigments and IAA. While the interaction between chitosan concentrations (50 mg/L) under salinity level (8000 mg/L) recorded the highest yield characters, except for crude protein (75 mg/L chitosan) in control plants (those plants irrigated with tap water). Conclusion In conclusion, chitosan treatments did not only improve plant growth and productivity but also could enhance the reducing effects of salinity stress on growth and productivity of sunflower plant. The most effective concentrations was 50 mg/L on increasing growth and yield of sunflower plant.