EFFECT OF PHOSPHORUS LEVELS AND TOPPING DATES ON YIELD OF TRANSPLANTED COTTON CULTIVAR GIZA 83

Two series of experiments were carried out at Mallawi Agricultural Research Station during 1993, 1994 and 1995 seasons on cotton culti­var Giza 83 to study: the effect of phosphorus fertilizer rates on trans­planted cotton (zero, 15, 22.5 and 30 kg P205/fed), and (2) the effect of topping dates on transplanted cotton at formation of, 6, 8, 10 and 12 branches/plant. A randomized complete block design with four repli­cations was used for each experiment. The results indicated that higher phosphorus fertilizer rate of 30 kg P205/fed increased final plant height, number of sympodia/plant, yield components per plant, and yield earliness and produced the first sympodia/plant at lower node on the main stem, while lint percentage and seed index were not significantly affected by phosphorus fertilizer. Seed cotton yield/fed. was significantly increased in favour of higher phosphorus rate of 30 kg P205/fed. Early topping date at formation of 6 fruiting branches/plant decreased final plant height, number of fruiting branches/plant, while later topping date at formation of 10 or 12 fruit­ing branches/plant increased number of open bolls/plant, seed cotton yield/per plant and per fed. Yield earliness and boll weight were slightly affected by topping dates, while lint percentage and seed index were not affected by topping dates.