Nitrogen and zinc effects on cotton yield and quality: Insights from a 6-year field study

Abstract

The physiological utility of nitrogen (N) and zinc (Zn) in cotton (Gossypium hirsutum L.) is interlinked, but the level of their contribution to nutritional balance and production remains unexplored. Therefore, this study explored the interactive effects of N and Zn on cotton lint yield, seed yield, and fiber quality under field conditions. The experiment was conducted from 2016 to 2021 within a randomized complete block design replicated five times, testing a full factorial treatment structure with four N rates (34, 67, 101, and 134 kg N ha⁻¹) and four Zn rates (0, 6, 11, and 17 kg Zn ha⁻¹). Overall, cotton lint and seed yield were significantly influenced by the three-way interaction between N, Zn, and year. Applying just N never resulted in high yield, except in 2017. Each year, applications of 101 kg N ha⁻¹ and 6 kg Zn ha⁻¹ were found to be the optimum rates, and in 2021 this combination resulted in the highest lint (1804 kg ha⁻¹) and seed cotton (4484 kg ha⁻¹) yields, while the lowest lint yield was recorded in 2016 when 34 kg N ha⁻¹ was applied alone. Increasing N rates from 34 to 101 kg N ha⁻¹ reduced micronaire by 6%, while the opposite was observed with Zn. Overall, the synergistic effects of both N and Zn were noted. Lint, seed, and fiber quality responses to N and Zn varied slightly each year, underscoring the annual environmental variations and the need for adaptive nutrient management plans.