PHYSIOLOGICAL RESPONSE TO SALINITY OF SOME TIMBER TREES SEEDL.INGS

Abstract

Salinity in soil or water presents a stress condition for crop plants that is of increasing importance in agriculture. It is estimated that a third of the world"s imigated area is already affected to some degree by excess salinity preliminarly caused by inadequate drainage. In addition, the need to produce more food is continually pushing agriculture further into marginal lands often characterized by soils and water with a high degree of natural salinity. Increasing salinity in Egyptian soils and rising water table levels represent hard prblems which could face crop production. Several woody trees and/or shrubs of the ornamental plants such as Eucalyptus, Casuarina and Cupressus have beneficial affected in each of the old and new cultivated lands, that may suffer from salinity. They reduce soil erosion and protect the fields from desicating wind. They also cultivate in cities as graden and shade trees in the streets, additional to its importance as a supply of raw material to feed some wood industries. Also, they are grown by farmers in marginal