الفهرس 
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Abstract
Bean, Phaseolus vulgaris, L is considered an important
vegetative crop in Egypt as well as many other countries in the world,
Therefore, the improvement of bean yield is always demanded. The
improvement of both quantitative, and qualitative traits specially
protein content of bean depends on the present of genetic variability
that permits effective selection. Hybridization and mutation are the
main sources of inducing genetic variability in plant Thus, combined
effects of hybridization and mutagenic treatments are more effective in
increasing the genetic variability The efforts of many investigators
were directed to study the effects of the ionizing radiation and
hybridization on the morphological, biological and physiological
changes accompanying the application of such mutagens.
Furthermore, they aimed to obtain new strains of plants different form
initial varieties and their crosses, with improved qualities permitting
effective breeding and ensuring high economic value.
Random mutations could increase the variance and cause shift
in the mean values of the characters away from the initial previous
means. Thus, the increasing of genetiC variation that appear in
the successive F, generation, after mutagenic treatments, permits
effective selection. Therefore, selection must be applied
simultaneously for all economic characters, if these characters are to
be maintained at the desired level,
The success of a given mutation program in producing new
strains of cultivated plants, depends on some factors. These factors
may be placed in two groups. The first, are those factors concerned
with the amount of useful and usable variation produced. These
include the efficiency of the mutagenes available, the efficiency with
which they are used and the manner in which the induced variation is
detected and utilized. The second group of factors, which have
received less attention, are those associated with the nature of the
induced variation.
The present investigation was planned to determine the effecls
severaldoses of gamma irradiation on variability, means, heterosis,
genetic parameters and heritability in bean varieties. The effect of
radiation was evaluated in the first (Mil and the second (M2)
generations for the parental varieties and the hybrids among them.