Growth Study of Some Local and Exotic Timber Tree Species Irrigated With Treated Waste Water

Abstract

This study was carried out in the Serapium Forest Plantation, Ismailia Governorate, Egypt during 2015-2018 seasons to study the response of certain tree species to treated waste water. The tree species that have been tested are Khaya senegalensis, Swietenia mahagoni, Azadirachta indica, Tectona grandis, Pongamia pinnata, Casuarina equisetifolia, Gmelina arborea and Corymbia citriodora. After three years of planting, the tallest plants were C. citriodora, followed by C. equisetifolia and Gmelina arborea. However, the highest increment in the diameter of trees was in C. citriodora, followed by G. arborea and C. equisetifolia in the first ranking.While, the smallest increase in number of branches was in C. citriodora as compared to the other tested species. The highest specific gravity value of wood was in C. citriodora followed by P. pinnata. For the fiber length, C. equisetifolia followed by K. senegalensis and P. pinnata resulted the highest values compared to other tree species. In respect of the accumulation of nickel (Ni) in the leaves, the highest values were obtained by C. equisetifolia and in the stem, the highest value in K. senegalensis, while G. arborea trees gave the highest values of nickel in the root. Concerning the accumulation of lead (Pb) in the leaves, the highest values was noticed with S. mahagoni, while in the stem was in K. senegalensis, and in the root, the highest value was in C. equisetifolia and S. mahagoni. It can be concluded from the herein study that using treated waste water in irrigating woody trees was more effective and associated with increment of growth parameters sequence produceing healthy trees and enhanced both of specific gravity and fiber length. On the other hand, it is evident that cultivating timber trees irrigated by waste water can be used as phytoremidiation by absorbing the heavy metals such as Ni, Pb and Cd which are not recommend in irrigation of the edible plants. It is possible to say that the trees under study can grow under the irrigation conditions of the treated waste water, and also expand their cultivation in the afforestation programs in Egypt for their environmental, economic and aesthetic importance, in particular the trees of Corymbia citriodora, Casuarina equisetifolia, Gmelina arborea, Khaya senegalensis, and Swietenia mahagoni .