EFFECT OF HILL SPACING AND REMOVAL OF TERMINAL BUD (TOPPING), TERMINAL SQUARE OF SYMPODIA (PRUNING) OR BOTH AT DIFFERENT PLANT HEIGHT OF GIZA 89 COTTON CULTIVAR

Two field experiments were carried out at Sakha Agricultural Re­search Station during 1996 and 1997 seasons on the new cotton culti­var Giza 89, to study the effect of hill spacing of 20,25 and 30cm (plant population) and plant growth alteration treatments i.e. topping , side branch bruning at 120 cm height, topping + pruning at 100cm height + pruning at 120 cm height on some vegetative and fruiting habits, earli­ness and seed cotton yield and its components. Generally the combined data clarified that wider hill spacing in­creased number of monopodia, main strem intemodes, sympodia, addi­tional fruiting branch bolls, retended bolls. fruiting sites, percentage of bolls on vegetative branches open bolls, boll weight and seed cotton-yield (Kintar/ fed.) while it decreased final plant height, number of aborted sites , days to finalt open boll, earliness percentage and number of unopen bolls. However , plant alteration treatments had a positive ef­fect on most studied traits and reverselly depressed number of monopo­dia, aborted sites and earliness percentage comparing with check. Within plant altering treatments, there are significant divergences. The results indicated that topping plants at 120cm height increased number of re-tended bolls, fruiting sites , days to first open-boll, open boll, unopen bolls and seed cotton yield (Kintar/fed.). Side branch pruning at 120 cm height increased final plant height, monopodia, main stem internodes, sympodia, earliness percentage and boll weight. Topping + pruning at 100cm height only decreased number of aborted sites. Topping + prun­ing at 120cm height increased additional fruiting branch bolls, percent­age of bolls on vagetative branches, boll weight and seed cotton yield (Kintar/fed.) Topping at 120 cm height and 30cm hill spacing which resulted in highest number of retended bolls and seed cotton yield.