COMPARISON AMONG SOME SELECTION PROCEDURES TO PRODUCE THE NUCLEOLUS ( BREEDER SEED ) OF THE EGYPTIAN COTTON VARIETY GIZA 92 ( GOSSYPIUM BARBADENSE L )

The main objective of this work was to compare between the selection methods of maintaining and renewing the breeder seeds of Giza 92 followed by the Department of Cotton Maintenance, Cotton Research Institute, A.R. C. , and selection index procedures for the possibility of selection higher yielding plants with the same fiber properties of Giza 92. To form the new nucleolus (breeder seeds) two selection procedures were followed, the first was the procedure followed by the Department of Cotton Maintenance based on selection the best families representing the type of Giza 92 variety. The second was the procedure of classical selection index with different applications of selection intensity. Yield and yield components as well as fiber traits were evaluated for seven nucleolus, one from the traditional method and six from selection index method. Mean results showed that the means of the selected families were slightly differ from comparisons, which indicate the homogeneity between these families, also values of SE and C.V. % were relatively low for all traits except for SCY and LCY confirming the homogeneity between these families and the influence of seed cotton yield (SCY) and lint cotton yield (LCY) by environmental factors. Heritability of the studied traits ranged from moderate 64.56% for yellowness (+b) to high 97.81% for uniformity index (UI %). These results indicate the possibility to maintain the standard characters of Giza 92 variety by simple selection for these traits. Factor analysis showed that, three classes of independent factors were chosen based on Eigen value > 2, which together compose 61.28% of total variation. Contribution of these three factors in total was 23.83, 19.32 and 18.13%, respectively. Due to the relatively important of traits in each factor, factor 1 considered yield factor, factor 2 considered yield and fiber factor and factor 3 considered fiber factor. Which exhibit the importance to compare the selection index procedure in this work based on yield traits alone, fiber traits alone and all traits. Genotypic correlation revealed that selection for the direction of yield improvement can simultaneously maintain micronaire value (MV) and yellowness (+b) in the range of the variety standard. On the other hand, genotypic correlation between fiber strength (FS) which characterize G 92, was undesirable (negative) with fiber length at 2.5% Span length (2.5%SL) and elongation (E%.) and positive with micronaire value (MV), this mean special balance must be consider at the selection for these traits. Regarding to predicted gains, Application-3 (using yield and yield components with selected three families) presented the highest desirable M.A.A. El-Dahan et al., 456 predicted gains for Boll weight (BW.) and Fiber length at 2.5% Span length (2.5%SL). The highest predicted gains for SCY and LCY were observed in Application-4 (using yield and yield components with selected seven families), because both seed and lint cotton yields exhibited greater magnitude of genetic variances across this application. Application-5 (using fiber traits with selected three families) presented the highest desirable predicted gains for seed index SI, lint index (LI), fiber strength (FS), micronaire value (MV) and brightness (Rd %), and Application-6 (using fiber traits with selected seven families) for lint percentage (L %), uniformity index (UI%), maturity ratio (MR) and yellowness (+b). It conclude that using selection index procedure to produce breeder seeds in Giza 92 variety could significantly improve seed cotton yield and lint cotton yield maintaining in the same time the standard fiber properties.