Application of Methyl Jasmonate and Chitosan on Behavior of “Anna” Apple Seedlings Grown under Water and Heat Stress Conditions

The role of methyl jasmonate and chitosan application as anti- stress materials on responses of “Anna” apple seedlings grown under water and heat stresses was evaluated during 2018 and 2019 seasons. Anna" apple seedling were exposed to three levels of water regiem reated to avaialable (100, 80 and 60%), kept in the plastic greenhouse conditions at 45 ± 2°C., and treated with MeJA at 1.0 and 2.0 mM as well as chitosan at 0.5 and 1.0 %. Vegetative growth parameters, leaf mineral contents, chemical constituents and physiological attributes were detcrmined through out the development of apple seedling abiotic stress. Vegetative growth parameters including plant height (cm), average stem diameters (cm), total number of leaves/ plant, leaf area (cm2 ), number of branches/plant and shoot lengths (cm), fresh and dry weights (g/plant) greatly affected with both studied factors. Application of methyl jasmonate at 2.0 mM and chitosan at 1.0 % combined with irrigation with the three levels of recommended water regien (100, 80 and 60%), were superior than other treatments or untreated one in recording the highest values of all vegetative growth parameters in both seasons. All anti -stress materials were effective in increasing apple seedlings levels of macro (N, P and K) and micro (Fe, Zn, Mn and Cu) elements compared to untreated apple seedlings. However, chitosan treatment at 1.0 % in combination with all water regiems were more effective in improving the nutrition status of treated seedlings. Additionally, high values of total chlorophyll and carbohydrates were achieved by apple seedlings irrigated with 100% of water regiem and sprayed with higher concentration from chitosan or methyl jasmonate materials. On the other hand, the untreated seedlings under all irrigation water regiems recorded the least values in this respect. On the contrary, the treatments of 2.0 mM methyl jasmonate and 1.0 % chitosan under heat and water stress conditions were effective in reducing proline amino acid, glycine betaine and phenolic compounds contents values which is similar to the apple seedling did not expose to stresses. Generally, it could be concluded that spraying apple seedlings with methyl jasmonate at 2.0 mM and chitosan at 1.0 % in combination with all water regiem considered a good horticulture application to alleviation of a biotic stress (water and heat).