Biofortification of Productivity of Egyptian Cotton Variety Giza 94 through Split Application of Nitrogen Fertilizer and Phosphorus Sources

Two field experiments were conducted at the Nubaria Agricultural Research Station in Giza, Egypt, located at 46 km southwest of Alexandria. The study aimed to evaluate the influences of splitting N fertilizer and different P sources on the seed cotton yield and its components of the Egyptian cotton cultivar Giza 94, a long-staple variety, during of 2021 and 2022 seasons. The experimental design was a split-plot design with four replications, where N splitting treatments (Twice, Thrice, and Four times) were assigned to the main plots, while the sub-main plots included sources of P fertilization (Super phosphate, Organic P, Phosphoric acid, and Phosphorien). The results indicated that growth and yield of Egyptian cotton were influenced by N splitting, P sources, and their interaction, particularly with three equal splits applied at 30, 45, and 60 days after sowingsowing (DAS). The first split occurred before the first irrigation (30 DAS), the second before the second irrigation (45 DAS), and the third before the third irrigation (60 DAS). The P application involved adding half a dose of Ca superphosphate during seedbed preparation, inoculating seeds with the biofertilizer Phosphorein at planting date, foliar application with 1.5 cm³ phosphoric acid per liter twice (after thinning and six days after the third irrigation at 66 DAS), and foliar application of 5 cm³ organic phosphorus (Pro Phos™ 0-20-0) per liter twice (at the squaring stage, 45 DAS, and flowering initiation, 80 DAS) in both seasons under Nubaria conditions.