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ASSIMILATION OF SULPHATE-SULPHUR AS INFLUENCED BY POTASSIUM NUTRITION IN COTTON (GOSSYPIUM HIRSUTUM L.)
M. I. Makhdum , H. Pervez
Abstract: A field experiment was conducted to study absorption of sulphate-sulphur (SO2-4) under varying levels of potassium (K) fertilizer in cotton (Gossypium hirsutum L.) plant. Treatments consisted of four cotton (Gossypium hirsutum L.) cultivars (CIM-448, CIM-1100, Karishma and S-12), four potassium fertilizer rates (0, 62.5, 125.0 and 250.0 kg K ha-1) and two sources of potassium fertilizer [sulphate of potash (K2SO4) and muriate of potash (KCl)]. Studies were carried out on silt loam, Miani soil series (Calcaric cambisols, fine silty, mixed Hyperthermic Fluventic Haplocambids) under irrigated conditions. The sequential harvests were collected at five stages of growth, viz; first flower bud, first flower, peak flowering, first boll split and maturity. Plants were divided into leaves, stems, burs, seed and lint at each harvest and analyzed for Sulphate-sulphur content. Sulphate-sulphur content was the highest during early part of growth period and then declined with ontogeny. Cultivars varied greatly in utilizing SO2-4 in various organs. Cultivar CIM-448 accumulated greater quantity of SO2-4 compared to other cultivars. Sulphate-sulphur content increased with concurrent increasing levels of K-fertilizer added in the form of K2SO4. Crop maintained SO2-4 in different organs in sequence of leaves> seed> burs> lint> stems. These studies showed that synergistic phenomenon existed between K+ and SO2-4 content in cotton plant.
Keywords: Gossypium hirsutum L., irrigated cotton, K-nutrition, potassium concentration, Sulphate-sulphur concentration, synergistic interaction; upland cotton.