根菜

The studies were made of growth and storage of some chemical compositions of sweet potato, potato and sugar beet under temperature conditions. Sweet potato and potato were grown at the following day-night temperatures, 15-13℃, 20-15℃, 25-20℃, 25-13℃, 15-15℃ and 20-20℃ for 3 weeks. The dry matter yield of top and tuberous root in sweet potato and those of top and root in potato increased as the temperature rose, but those of potato tuber was higher at 20-15℃ than at 25-20℃, and at 25-13℃ than at 25-20℃. Nitrogen and phosphorus contents of top in the two crops decreased as the temperature rose and starch and nitrogen contents of storage organ in the two crops increased as the temperature rose. The storage rate of carbohydrate in potato root increased as the temperature fell, and was highest in 15-13℃. When sugar beets were grown at the following day-night temperatures ; 17-14℃, 22-17℃ and 27-22℃ for 5 weeks, top fresh weight increased with the rising temperature and the greatest fresh weight of root resulted in plants grown at a soil temperature of 22-17℃, while sucrose content in root decreased with the rising temperature. When sweet potatoes were grown at soil temperatures of 20℃, 30℃ and 40℃ during the daytime for 3 weeks, the dry matter yield and storage rate of carbohydrate in root were the highest at the soil temperature of 30℃. Dry matter yields of those plants grown at the same soil temperatures during night were the highest at 20℃ and decreased as the soil temperature rose. When sweet potatoes were grown at the soil temperatures of 15℃ and 30℃ under the two different air temperature conditions (day-night temperatures; 20-15℃ and 25-20℃), the dry matter yield of top was higher at the soil temperature of 30℃ than at 15℃ under both air temperature conditions. Under the low air temperature condition, the dry matter yield of tuberous root was higher at the soil temperature of 15℃ than at 30'C, but the yield was higher at 30℃ than at 15℃ under the high air temperature condition. The storage rate of carbohydrate in root was higher at 15℃ than at 30℃ under both temperature conditions. When potatoes were grown at the soil temperatures of 10, 20 and 30℃ for 3 weeks, the dry matter of tuber and storage rate of carbohydrate in root increased as the soil temperature decreased to 10℃. When sugar beets were grown at the soil temperatures of 12, 17, 22 and 27℃ for 5 weeks, top fresh weight increased as the soil temperature fell to 17℃, but the sucrose content of root steadily increased as the soil temperature fell from 27℃ to 17℃.