EFFECTS OF NITROGEN FORMS AND PH INTERACTION ON ROOT YIELD AND SUGAR CONTENT IN SUGAR BEET Effects of Nitrogen Application Rates on Root Yield and Nitrogen Utilization in Different Purple Sweetpotato Varieties Comparison of Root Characteristics and Sugar Components in Root and Leaf at Early Growth Phase of Sweet Potato Varieties with Significant Difference in Valid Storage Root Number Contrast of growth characteristics of different germplasm and correlation between morphologic and individual yield of Isatis indigotica Effects of Plastic Film Mulching Cultivation on Young Roots Growth Development, Tuber Formation and Tuber Yield of Sweet Potato EFFECTS OF THE SOIL AERATION ON NUTRIENT ABSORPTION, ~(14)C-ASSIMILATES DISTRIBUTION AND STORAGE ROOT YIELD IN SWEET POTATO The growing character of sugar beet leaf and its effect on yield and sugar content in beet root in Loess plateau