A field experiment was conducted during rainy season of 1997 and 1998 on silty clay loam soils sufficient in available copper status (0.8 ppm) to study the influence of copper on physiological growth parameters arid potassium uptake in soybean (Glycine max L. Merrill). Application of copper did not influence physiological growth parameters and grain yield except leaf area index which increased upto 5 kg Cu ha−1 showing 6.89 and 6.22 per cent increase over control and 2.5 kg Cu ha−1 respectively. Interaction between varieties and copper levels was significant for grain yield and potassium uptake. PK416 at 5 kg Cu ha−1 recorded highest grain yield followed by PK 1042 and PK 262 whereas Bragg yielded lowest. Highest potassium content and uptake of grain were obtained at 2.5 kg Cu ha−1. Residual available copper left after soybean, increased significantly with increasing copper levels whereas available potassium in soil increased only upto 5 kg Cu ha−1. Soybean genotypes responded significantly to differential rate of copper application indicating PK 416 can be grown in copper rich soils, whereas Bragg in low copper containing soils.