AbstractTwo experiments were carried out at Giza Agric. Res. St., Agric. Res. Centre, Mins. of Agric., Egypt, during 1981 and 1982 seasons on cotton cultivar Giza 75 (Gossypium barbadenseL.), to investigate the influence of nitrogen rates (72, 144 or 216 kg N/ha), phosphorus rates (36 or 72 kg P2O5/ha) and three growth regulators, i.e. indole‐3‐acetic acid (IAA), indole‐3‐butyric acid (IBA) or 1 naphthalen acetic acid (NAA), each was sprayed with 10 ppm at three times 70, 85 and 100 days after sowing, on yield components, cotton yield and fiber properties. The design of the experiment was randomized complete blocks with four replications.The data obtained showed that, the number of bolls/plant, boll weight, seed index, seed cotton yield/plant and seed cotton and lint yield/ha increased by increasing N rates and under the application of IAA, IBA or NAA. Lint index increased by applying the growth regulators, while it was not affected by N rates. Lint percentage decreased by raising N level, whereas it was not affected by the growth regulators. The number of bolls and seed cotton yield/plant, seed cotton and lint yield/ha increased, while the other yield components were not affected with the increase in the added P. In general, all the fiber properties tended to improve slightly by applying the three growth reg
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