Growth and Mineral Status of Moringa Plants as Affected by Silicate and Salicylic Acid under Salt Stress

For evaluation of moringa growth and its minerals content response to irrigation with diluted seawater and spraying by potassium silicate solitary (Si) or in combination with salicylic acid (Si+SA), a pot experiment was conducted in the greenhouse of the National Research Center, Cairo, Egypt. Negative relationship was shown between salt stress degree and plant growth characters i.e. plant height, leaves area and dry weight of root, stem and leaves, which decreased as the salt concentration increased in the diluted seawater. Nevertheless, shoot/root ratio and leaf water content were increased with salinity increased. All growth characters increased with Si+SA addition. While adding sole silicate gave more plant height than the combined application without significant difference between them. The highest positive effect was shown when plants irrigated by tap water and spraying with Si+SA together. Significant depressions were obtained in nitrogen concentration or content as a result of growing moringa plants under salinity condition. Similar response in P content but the differences were not significant. Calcium and K concentrations did not significantly responded with salinity but Mg concentration decreased significantly only with the first level of salinity. Calcium showed its higher increment in content by spraying single Si under fresh water treatment. In most cases, application of potassium silicate in combination with salicylic acid gave the higher increases in mineral content estimated in this work. This means that, a synergistic effect was found between these two materials.