الفهرس 
INTRODUCTION .Only 14 pages are availabe for public view
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Abstract
A set of experiments were carried out at the greenhouse and tissue culture Laborat01y of the National Research Centre.
The work was divided into two main groups : A. Experiments of seed germination :
Five experiments were carried out in the tissue culture
laborat01y, these experiments were as follows :
1. First Experiment : Aimed to study the response of some vegetable crops seeds (tomato, lettuce, cabbage and carrot to the different salinity, concentrations (0, 2000, 4000, 6000,
8000 and 10000 ppm)
2. Second Experiment : Aimed to investigate the effect of different degrees •of temperature (optimum temperature , l0°C, 32°C) on seed germination of some vegetable crops (tomato, lettuce, cabbage and carrot).
3. Third Experiment : aimed to study the effect of different levels of stomp herbicide (0, 2000, 4000, 6000, 8000 and
10000 ppm) and different levels of Giza gard herbicide
(0,1000, 2000, 3000, 5000 and 7000 ppm) on germination
percentage, germination rate index, hypocotyl and radical length of the some mentioned vegetable crops.
4. Fourth Experiment : Aimed to study the effect of root exudates of carrot, lettuce, cabbage and tomato seedlings on the germination of the same vegetable crop seeds.
5. Fifth Experiment : aimed to collect seeds exudates for chemical determinations of seeds exudates.
The obtained results could be summarized as follows :