CONSTRUCTION OF SOME SELECTION PROCEDURES FOR IMPROVEMENT LINT YIELD IN EGYPTIAN COTTON

The aim of this study was to estimate and compare the genetic gain obtained from Smith-Hazel index model of selection index with direct selection to enhance selection efficiency of superior promising families in early segregating generations of the cotton cross Giza 86 x aust2. The data revealed increase in mean values for all characters with advanced generations' from F-2 to F-4. The advanced generation (F-3 and F-4 generations) showed reduction in PCV and GCV values. A significant desirable correlation was existed between boll weight and each of seed/boll, seed index and lint/seed over the three generations. Some relations were changed from negative to positive (desirable direction) over generations. The highest predicted genetic gain from F-2 (and) F-3 generations for lint yield/plant was observed when applied index selection contained lint yield/plant with bolls/plant (IWO followed by (Iw(123)) selecting for lint yield/plant, boll/plant with seed/boll and lint/seed, selection index involving lint yield/plant, bolls/plant and lint/seed (Iw13), index selection Iw23 and Iw2. The highest realized genetic gains from F-3 generation for lint yield/plant occurred when selecting for IW12 (Selection index involving lint yield/plant, bolls/plant and seeds/boll) followed by Iw(123) (Selection index involving lint yield/plant, bolls/plant, seed/boll and lint/seed. Most indices showed high discrepancy between predicted and actual genetic gain as lint yield/plant and most showed negative values, this was due to non-additive gene effect and large effect of environmental factor. Selection index involving lint yield/plant and boll/plant surpassed all selection procedures for predicted gain. However selection index involving lint yield/plant, bolls/plant, seeds/boll and lint/seed followed by selection index involving lint yield/plant, bolls/plant and lint/seed appeared to be most effective for the improvement lint yield and gives reasonable actual gains. Breeder may utilize selected families in breeding programs aiming to improve yield and quality.