IMPROVING TOLERABILITY OF TAXODIUM DISTICHUM SEEDLINGS TO WATER SALINITY AND IRRIGATION WATER DEFICIENCY II. EFFECT OF SALICYLIC ACID ON SALINITY STRESS

Abstract

This study was carried out at the nursery of Horticulture Research Institute, Agriculture Research Center, Giza, Egypt in the two years, 2016 and 2017, aiming to investigate the effect of salicylic acid at different level (0, 0.5, 1.0 and 1.5 g/l) on growth and chemical composition of Taxodium distichum under salinity stress at four concentrations (0, 4, 6 and 8 g/l NaCl). The results revealed that, salinity levels significantly decreased growth parameters, i.e. seedlings height, branches number, root length and shoot, root fresh and dry weight. Also salinity decreased total carbohydrate content and total chlorophyll content in leaves. Salicylic acid application significantly increased growth parameters under salinity stress as compared with salinity treatment without salicylic acid application. Application of 0.5 g/l salicylic acid recorded the best results. Also, combinations that occupied the highest position were: salicylic acid at 0.5 g/l with salinity at 4 and 6 g/l for shoot dry weight and root fresh weight; salicylic acid at 0.5 g/l with salinity at 0 g/l for branch number, root length; salicylic acid at 0.5 g/l with salinity at 4 g/l for plant height 2nd year, root dry weight and total chlorophyll content; salicylic acid at 0.5 g/l with salinity at 6 g/l for plant height in the 1st year and root dry weight; salicylic acid at 1.0 g/l with salinity at 0 g/l for branch number in the 1st and 2nd years and shoot fresh weight; in addition to salicylic acid at 1.0 g/l with salinity at 4 g/l, salicylic acid at 1.5 g/l with salinity at 0 g/l and salicylic acid at 1.5 g/l with salinity at 4 g/l for shoot fresh weight. Combinations that obtained the lowest grade were: salicylic acid at 0 g/l with salinity at 8 g/l for root length, root fresh weight, root dry weight, total carbohydrate content and, total chlorophyll content. It is recommended to in case of irrigation water or soils afflicted with salinity, it is advised to apply salicylic acid at 0.5 - 1.5 g/l as to alleviate salinity stress. So that it could be concluded that the addition of 0.5-1.5g/l of salicylic acid are beneficial to mitigate the adverse effects of salinity stress of T. distichum seedlings.

Keywords

• taxodium distichum
• salicylic acid
• salinity stress
• bald cypress
• conifer