NPK fertilization in the productive capacity and fiber quality of Tangüis Cotton (Gossypium barbadense L.)

Peruvian cotton is recognized worldwide for its excellent quality, with the Tangüis and Pima varieties of long and extra-long fiber stand out as the ones with the best fiber quality and occupy the largest planting area. For this genetic potential to be expressed, adequate agronomic management is important, with fertilization being essential to achieving this objective; under this premise, a trial was installed in the Irrigation Research Unit of the Department of Soils of the Universidad Nacional Agraria la Molina (UNALM) in the 2021-2022 campaign. Two commercial varieties of Tangüis cotton were evaluated; MASSARO and UNA N°1 and a new variety MOLINERO EXTRA LARGO, obtained from the cross of Tangüis and Pima, testing three levels of nitrogen, phosphorus, and potassium fertilization, 80:40:80, 120:60:120 and 160:80:160 kg NPK/ha, and an unfertilized control. The statistical design was complete randomized blocks in factorial arrangement, with twelve treatments and 4 replications. Each treatment was installed in an experimental unit of 3.4m2. This research was conducted in sandy loam soil, moderately saline, with low potential and basic fertility. The results show that NPK fertilization significantly affects the yield in the branch, fiber, number, and weight of the boll. The yield trend is linear, with a 46 % increase at 160:80:160 kg NPK/ha compared to the control. The response between varieties indicated that MOLINERO EXTRA LARGO had the highest yield of raw cotton (3589 kg.ha-1) and fiber (1200 kg.ha-1), different from UNA N°1 by 12 % and from MASSARO by 23 %. Regarding fiber quality, there was no significant response to fertilization. However, at the variety level, MOLINERO EXTRA LARGO produces the finest fiber, with a micronaire value of 4.2, the greatest uniformity (89.5 %), and the longest fiber length 39.8 mm, 6 % greater than UNA N° 1 and 19 % greater than MASSARO. Finally, UNA N°1 showed mean values in fiber quality between MOLINERO EXTRA LARGO and MASSARO, the latter is characterized by its higher resistance (33.6 g/tex) and lower fineness (5.3 micronaire).