الفهرس 
GENERAL INTRODUCTION
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Abstract
This study was conducted during the period from 2012 to 2015 at the tissue culture laboratory of Fruit Crops Department, Faculty of Agriculture, Assiut University using shoot tips to study the effect of sugars as a carbon source, amino acids and salinity stress on growth of some citrus rootstocks in vitro. All culture techniques were carried out in a laminar flow sterile cabinet to ensure aseptic conditions.
The objectives of this investigation were to:
1. Study the effect of sugars and amino acids on vegetative and rooting growth in vitro of some citrus rootstocks.
2. In vitro evaluation for salt tolerance of some citrus rootstocks via studying the effects of two salinizing agents (NaCl, CaCl2) on some morphological, physiological and biochemical aspects.
Shoot tip explants (0.5 cm) of four citrus rootstocks (trifoliate orange, sour orange, volkamariana and lime) were cultured on MS medium including vitamins supplemented with100 mg/l myo-inositol and 2.5 g/l gelrite. Three types of sugars (sucrose, fructose, glucose) were used at different concentrations (88, 132 and 176 mM) and two types of amino acids were used as tryptophan at 0, 50, 75 and100 μM and glutathione at 0, 5, 10 and 20 μM. Two salinizing agents (NaCl, CaCl2) supplied in different concentrations were used as follow: I) NaCl at 0, 40, 80 and 120 mM, II) CaCl2 at 0, 1, 3 and 5 mM, and III) Mix at 0, 45 (40 NaCl + 5 CaCl2) and 85 (80 NaCl + 5 CaCl2) mM. Growth regulators were used during multiplication and rooting stages as follow: a) multiplication, BAP at 1.0 mg/l and b) rooting, IBA at 0.5 mg/l. The pH was adjusted to 5.6-5.8 before autoclaving at 1.5 kg/cm2 pressure and 121°C temperature for 20 min. The vessels were placed in incubation room at 23±2°C, under 16 h light/8 h dark photoperiod. Each treatment consisted of 15 repetitions (15 jars).