Level of potassium affects concentration and uptake of nutrients in bt. cotton.

The present study was carried out at the farm of Krishi Vigyan Kendra, Sirsa in a sandy loam soil, low in organic carbon and nitrogen, medium in phosphorus with medium to high potash levels. Bt. cotton (var. Bioseed-6588) seed was sown in two soils with varying potassium (K) levels. The treatments comprised of T - ^T2 - ^N175^P60 + Water Spray ^T3 - ^N₁₇₅ 1% foüar spray of KNO₃ - T₄ - ^N₁₇₅^p₆₀+ T₅ - ^N₁₇₅^p₆₀+K₃₀+1% foliar spray of KNO₃, T₆ - N₁₇₅P₆₀+K₆₀ and T₇ - N₁₇₅P₆₀+K₆₀+ 1% foliar spray of KNO₃. The two foliar sprays were done at the time of early and peak boll development stages. Application of K increased the N content in the plant parts. P content in different plant parts decreased in all the treatments over treatment where only recommended dose of N and P applied. The relative K concentration in plant parts followed the order: leaves > bur > seed > stems. The mean N uptake in various plant parts in medium K fertility soil was lower as compared to the same in high K fertility soils. The mean P uptake was slightly higher in high K fertility soils as compared to the medium K fertility soils. The uptake showed a decreasing rate as the level of K increased.