الملخص
This study aimed to explain the influence of growth regulators (GRs) [Ascorbic acid (ASA) and Gibberellic Acid (GA3)] and Moringa Leaves Extract (MLE) on physiological aspects for two tomato (Lycopersicon esculentum, L.) cultivars (cv. Cobra) resistant and (cv. Newton) sensitive to salinity stress, for alleviating salinity stress. The tomato seeds for both cultivars soaked in ASA (0.75 mM); GA3 (0.05 mM) and MLE (5%) before germinated for 12 hours in the dark. The seeds of tomato planted in trays of cork contain 218 eyes for 14 days, seedlings plant transplanted to plastic containers containing a mixture of sand/peat-moss (1:2). The tomato seeds watering using distilled water until the true leaf appearance then transferred to a larger pots which containing the same mixture of soil as mentioned above. The experiment was carried out under greenhouse conditions with temperature 18oC±1oC (night) and 22oC ± 2oC (day) and relative humidity varied between 60 - 70%. The tomato plant irrigated with NaCl salinity concentrations (0, 50, 100,150 and 200 mM) alternative with Hoagland nutrient solution.Overall, the results indicated that the salinity treatments decreased significantly seeds germination rate (%), growth parameters (shoot height and root depth; leaves number and area; fresh and dry weights); water relation (succulence and relative water content) and photosynthetic pigments content (chlorophyll a, chlorophyll b, carotenoids, and total pigments contents) with increasing NaCl salinity concentrations compared to control. Whereas, the seeds soaking before germination in GRs (ASA and GA3) and MLE get an increased all parameters as mentioned above compared to control. Meanwhile, the evident recorded an increasing significantly the non-nitrogenous organic components (carbohydrates- Monosaccharide’s - Sucrose - Polysaccharides and Total Available Carbohydrates); organic nitrogenous components (Total Soluble Proteins; Total Amino Acids; Proline; Antioxidant Enzymatic Activity (CAT), (APX), (GR), (SOD); inorganic macro-mineral nutrient elements (N3+, Ca2+); micro-nutrient mineral elements (Mn2+, Fe3+, B2+), and decreased (P3+, K+, Mg2+, Na2+ and Cl–) contents. Also, the results illustrated that the tomato seeds soaked before germination in GRs and MLE which leads to remarkably increasing more for all parameters and physiological studies than in the absence. The data provide strong support to the hypothesis that exogenous application of GRs (ASA and GA3) and MLE in both tomato cultivars decreases the deleterious impact of salinity stress and increases resistance to salinity stress. Generally, the role of ASA, GA3 and MLE were one of the main mechanisms used by the plant to raise its efficiency to bear the salt stress compared to the control. Therefore, should be pre-treatment (soaking) of tomato seeds for both cultivars in ASA (0.75 mM); GA3 (0.05 mM) and MLE (5%) before germinated for gave the best results and more effective for overcoming the harmful impacts of salinity stress and produced new strain adapted to salinity stress.
