Effect of salt stress on some chemical components and yield of potato

To obtain more information about the effect of salt stress on potato production, the effects on emergence, growth and yield, carbohydrate and mineral contents, and nitrate reductase (NR) activity of potato plants (Solanum tuberosum L.) were investigated using two cultivars (May Queen and Dejima). Salt stress was achieved by the application of NaCl (0, 10, 20, and 30 g pot(-1) and the corresponding EC, values were 0.20, 0.77, 1.37, and 1.95 dS m(-1) respectively). Emergence was delayed, growth and dry matter production, especially in tubers, were depressed with the increase in the salt level. The salt stress decreased the total and marketable tuber yield due to the decrease in the tuber number per plant and average tuber weight. The contents of water-soluble carbohydrates (WSC) and starch of leaves increased and that of total nonstructural carbohydrates (TNC) also increased by salt stress. The WSC and starch contents of stems increased at the early stage of,growth, while at the later stages, both the WSC and starch contents decreased and also the TNC content decreased by salt stress. Sodium content of leaves, stems, and tubers markedly increased with the increase of the salt level. Potassium content of leaves decreased but in stems and tubers it increased by salt stress. Calcium content of leaves and stems decreased but in tubers it increased due to the increase of the salt level. Tuber N content increased by salt stress. The leaf NR activity was suppressed by salt stress, and the increase of the salt level decreased the NR activity throughout the season. It was concluded that the yield decrease caused by salt stress was due to nutritional imbalance, resulting in the inactivation of enzymes such as NR.