Effect of silver nitrate on induction of staminate flowers in gynoecious cucumber line (Cucumis sativus L.)

Cucumber is the second largest vegetable cultivated under greenhouse in Albania. Being so important for our country, the Vegetables and Potato National Research Institute is working intensively to create and introduce new hybrids suitable for the Albanian climate. Our breeding work is based on the creation of new hybrids from crosses of different gynoecious lines by inducing staminate flowers. The present study was carried out to investigate the effect of silver nitrate (AgNO3) concentration and number of sprays on sex expression of gynoecious, parthenocarpic, cucumbers. The initial sprays were applied at the first true leaf stage of growth, and subsequent treatments were applied at weekly intervals. Treatment effects were evaluated through anthesis at the loth node. Induction of staminate flowers is dependent upon AgNO3 concentration and number of sprays. All treatments using one spray were ineffective in producing staminate flowers. The treatments with 100 ppm failed to induce staminate flowers. The greatest number of staminate nodes was produced on plant sprayed 2x or 3x with 400 to 500 ppm AgNO3. Plants showing injury a few days after spraying with 400-500 ppm recovered within 7 to 10 days. These results demonstrate that commercial seed production of gynoecious hybrids is feasible when the staminate parent is gynoecious, which permits maintaining gynoecious inbreeds.