الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Seed polymorphism or seed heterospermy is defined as is the production of seeds of different morphology or behavior on different parts of the same plant and is a somatic differentiation rather than the result of genetic segregation. This phenomenon has been reported in a number of weedy annuals that occupy unpredictable environments. This phenomenon helps plants to respond directly to changing in environmental conditions and also reduces the competition and mating between sibling and protection against seed predation. The aim of the present study is to identify the genetic diversity characterization in six Egyptian taxa characterized by seed polymorphism. All the six taxa are collected from their natural habitat in North Mediterranean coast and Delta in Egypt and divided into three groups as the following: seed shape, seed size and seed colour polymorphism. Seed shape polymorphism is refers to shape variations in seeds produced by a species. This phenomenon is studied in both Emex spinosa and Limbarda crithoides. In Emex spinosa, two different seed were observed in the same plant in different position as follow: aerial seeds and subterranean seeds. For Limbarda crithmoides, the two different morphs in shape are observed from the same inflorescences. Seed size polymorphism knows as size variations in seeds produced by a species Both Cakile maritia and Raphanus raphanistrium have two different seeds size (large and small seed). Seed colour polymorphism refers to the variation in seeds colour in the same species. This phenomenon is observed in both Chenopodium murale and Urospermum picroides. In Chenopodium murale, two different seed are observed with different colour (black and brown seeds). Urospermum picroides has three different seed in colours (black, brown and white seeds) are observed in the same inflorescence. Genetic diversity was studied using cytological studies including somatic chromosome count; biochemical was represented by proteins profiles via SDS-PAGE and molecular studies by using RAPD, ISSR and SCoT techniques.