REDUCING THE HARMFUL EFFECT OF SALINE IRRIGATION WATER ON GROWTH AND QUALITY OF (Enterolobium contortisiliquum) ELEPHANT'S EAR SEEDLINGS

The current study was conducted in order to avoid hazards of saline irrigation water on elephant's ear tree (Enterolobium contortisiliquum (Vell.) Morong) seedlings. The experiment was done under the full sun at the nursery of Hort. Res. Inst., ARC, Giza, Egypt during 2017 and 2018 seasons using six-month-old uniform seedlings. The seedlings were planted in 30-cm-diameter plastic pots filled with about 5.5 kg/pot of sand and clay mixture at equal parts (1:1, v/v), drenched monthly with 0, 2 and 4 g/pot (plant) of magnetite (Fe3O4) and irrigated with saline water containing NaCl + CaCl2 mixture at concentrations of 0, 1000, 2000, 3000 and 4000 ppm. The results showed that plants irrigated with saline water at concentrations higher than 1000 ppm without magnetite died, while those amended with magnetite at either 2 or 4 g/pot survived regardless of the salinity level. However, the means of plant length, stem diameter, No. leaves/plant, root length and stem, leaves and roots fresh and dry weights of those plants were gradually decreased with increasing salinity level to reach the minimum values by the highest level (4000 ppm). The opposite was correct regarding the effect of Fe3O4, as the means of various top and root growth parameters were linearly increased as a result of the progressive increment of magnetite dose with the superiority of 4 g/pot dose that gave the highest records in most cases. The previous characters were also affected by the combined treatments, where the plants received magnetite at either 2 or 4 g/pot and irrigated with fresh water generally recorded the utmost high averages over control, and the interaction treatment of fresh water + 4 g/pot magnetite was the most effective one. A similar trend was also attained concerning the chemical composition of the leaves, as the concentrations of chlorophyll a and b, carotenoids and total carbohydrates were gradually decreased, but those of Na, Cl and proline were progressively increased the level of salt in irrigation water was increased. Magnetic iron, however improved concentrations of these constituents under the different salinity levels. The combination of fresh water + 4 g magnetite /pot scored the maximum concentrations of chlorophyll a and b, carotenoids and total carbohydrates, but that was true for Na, Cl and proline concentrations in plants irrigated with 4000 ppm saline water and supplemented with either 2 or 4 g/pot magnetite. Hence, it can be advised to use 4 g magnetite/ plant as a soil drench every month during the growing season in order to protect Enterolobium. contortisiliquum seedlings from salinity hazards.