Coupling effects of silicon and calcium foliar application and potassium soil fertilization on growth and yield production of cotton plants under drought stress conditions

Abstract

Drought significantly affects cotton production, decreasing both yield and fiber quality. This study investigated how foliar applications of calcium (Ca) or silicon (Si), along with varying potassium (K) levels in the soil, can improve drought tolerance in cotton. The foliar treatments involved calcium nitrate at 4 g/L or silicon oxide at 1 ml/L, combined with 106.6 and 160 kg K₂SO4 ha⁻¹ as soil fertilizer. These treatments were compared to potassium-only applications, with irrigation intervals of 30 days during the 2021 and 2022 growing seasons. The 160 kg K₂SO4 ha⁻¹ treatment notably improved plant growth, including increased plant height, dry weight, leaf area, and the number of fruiting branches, compared to the 106.6 kg K₂SO4treatment. It also enhanced chlorophyll content, antioxidant enzyme activity, leaf phenol and proline levels, and relative water content (RWC). Additionally, the 160 kg K₂SO4 ha⁻¹ treatment improved yield-related traits, such as the number of open bolls, lint percentage, seed index, and fiber quality, including fiber length, strength, and micronaire. The number of open bolls, lint percentage, and seed index increased by 2.38%, 1.71%, and 1.68% in the first season, and by 4.29%, 1.57%, and 1.38% in the second season, respectively. The combination of Ca or Si foliar applications with K treatments further enhanced plant growth, chlorophyll, antioxidant activity, RWC, seed index, boll weight, and fiber quality. These treatments also raised nutrient levels of N, P, K, Ca, and Si compared to the control. Overall, combining Ca or Si sprays with 160 kg K₂SO4 effectively mitigated drought stress and improved cotton growth and productivity.