Effect of Potassium and Sucrose Concentrations on the Production of Potato Microtubers Through Tissue Culture

This investigation was carried out on potato (Solanum tuberosum) cultivar "Alpha" where shoot tips were cultured on solid MS medium supplemented with 3% sucrose and 1 mg/l of BA for four weeks. Multinodal (three nodes) explants were excised from proliferated shoots and were subcultured on MS media with different strengths (25, 50 and 75 % strength of MS medium) enriched with potassium nitrate (at concentrations of 475, 950, 1425 and 1900 mg/l), potassium di-hydrogen-ortho-phosphate (at concentrations of 42.5, 85.0, 127.5 and 170 mg/l), and sucrose (at concentrations 25, 50, 75 and 100 g/l) to produce microtubers under long day (LD) and dark conditions on growth-regulator-free mediums. The results indicated that maximum number of microtubers was produced on MS medium with 25% strength supplemented with 25 g/l sucrose under LD conditions, whereas under dark conditions, best results were obtained from cultures on 75% strength MS mediums enriched with 950 and 1425 mg/l KNO3. It was also found that regardless of MS medium strength, sucrose additives resulted in the production of microtubers with the heaviest weights under LD conditions, while under dark conditions, all potassium supplements produced relatively heavy microtubers. Finally, MS medium with 25 % strength supplemented with 170 / l KH2PO4 produced the largest microtubers under LD conditions, while 75 % MS medium with supplemented with 127.5 g/l KH2PO4 under dark conditions produced the largest microtubers.