Two field experiments were carried out at Gharbia Governorate, El-Gemmeiza Agricultural Research Station, Egypt, during 2019 and 2020 seasons using the cotton cultivar Super Giza 86 (Gossypium barbadense L.) to study the effects of N [number of splits; (2, 3 and 4 splits) and time of application], P [sources; mineral, natural, bio-fertilizer, phosphoric acid, and mixture of these sources, time, and method of application] as well as their interactions. The experimental design was a strip plot with three and four replicates in 2019 and 2020 seasons, respectively. The important results indicated that two equal N splits resulted in a significant increase in growth parameters, earliness attributes (except boll shedding% which was decreased), seed cotton yield and its components in both seasons and significantly increased fiber length and fiber uniformity ratio in one season. However, fiber length increased in the second season in favour of four equal N splits. Fiber strength and fineness did not affect.
Sources of P application when used in mixture or in organic form recorded a significant increase in all studied traits, except boll shedding% which was decreased whereas fiber length, and fineness which was not affect in the second season.
The best results were obtained from two equal N splits combined with the mixture of different P sources or with foliar spraying with organic P twice. It could be concluded that, this interaction treatment under El-Gemmeiza condition, increased cotton productivity and quality especially in vigour's cultivar like Super Giza 86.