This study was conducted to investigate the effects of different foliar potassium treatments on greenhouse seed yield and quality of BT BUR - KAP capia pepper (Capsicum annum) cultivar. In addition to soil available K2O content, 1, 2, 4 and 8 kg da(-1) K2O treatments were performed with 15% nitrogen-containing potassium nitrate fertilizer. The greatest seed yield (34.50 kg da(-1)) was obtained from 2 kg da(-1) K20 treatment. As compared to the control treatment, 2, 4, 8 kg da(-1) K2O treatments yielded better seed germination ratios and mean germination times. For under-cover capia pepper seed production, seed yield and quality, the best outcomes were achieved with 2 kg da(-1) K2O treatments. Seed macro and micro elements and pre-harvest leaf amino acids were also investigated in this study. While all treatments yielded similar Mn, B, Fe, Cu, S and Na contents with the control treatment, K, Mg, Ca, P, N and Zn contents of potassium treatments were greater than the values of the control treatment. As compared to the control treatment, potassium treatments increased leaf total amino acid, cysteine, valine, tryptophan, leucine, proline, aspartate, asparagine, serine, glutamine, glycine, arginine and tyrosine contents. It was concluded based on present findings that in greenhouse capia pepper seed production, 2 kg da(-1) K2O treatments had the best outcomes for seed yield, germination and vigor.