الفهرس | Only 14 pages are availabe for public view |
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. |