THE EFFECT OF DIFFERENT WATER REGIMES ON MORPHLOGICAL, PHYSIOLOGICAL AND ANATOMICAL CHARACTERISTICS OF SOME CITRUS ROOTSTOCKS

Abstract

This experiment conducted during two successive seasons 1999 and 2000 to study the effect of four irrigation levels on four citrus rootstock seedlings namely sour orange Citrus aurantum ,Cleopatra mandarin Citrw reshni Hort.ex Tan , Volkamer lemon Citrus Volkameriana Ten. anc pasq and Troyer citrange[(C. sinensis (L)osh .)x(Poncirus lrifoliat' (L)Raf )]at the Horticultural Research institute, Giza Governorate Egypt.One-year-old seedlings were planted individually in black polyethylene bags filled with nonsaline sandy soil under 53% shaded greenhouse equipped with a drip irrigation system. The levels of water regime were as follows: !-Control treatment (field capacity): plants were maintained at field 2-Waterlogging treatment: plants were kept flooded under tap water. 3-Water stress treatment: plants were rewatered at 75% of field capacity. 4-Drout treatment: plants were rewatered at 50% of field capacity. The measurements included the following points: growth parameters, physiological aspects, chemical analysis of leaves and anatomical studies. The obtained results could be summarized as follows: • Volkamer lemon was the superior for its vigorous growth, physiologica potential to adapt itself against the different levels of water, its capacity to absorb minerals more than other rootstocks under shortage of water o waterlogging and finally the anatomical structure of leaves and roots whid cleared that it had the most surviving tissues under the different wate regimes. • Troyer citrange came in the second rank and characterized by vigor growth and good performance especially under the water defect. •Cleopatra mandarin exhibited the least values of most vegetative, physiological and chemical parameters which shown clearly in its anatomical structure. •The traditional rootstock sour orange had intermediate values in concerning the waterlogging conditions while it obtained less value under the water deficiency. Therefore, it could be recommended Volkamer lemon as a promising rootstock for waterlogged, high water-table soils or arid lands under the conditions of the present study and resembling