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

Abstract

Starch sweet potato varieties Shangshu 19 and Jixu 23 differing in valid storage root number per plant significantly were used to investigate root characteristics, sugar components in root and leaf at early growth phase and their relationship with the formation of storage root per plant at top cover stage. The results showed that, Shangshu 19 with higher valid storage root number regrew quickly with more new roots after seedling transplanting, developed fiberous roots mainly in the whole early growth phase, and formed a stable rate of top biomass/total root system biomass (T/TR) at 15 and 30 days after planting. Jixu 23 achieved the steady number of adventitious root and valid storage root at 15 and 30 days after planting, respectively. Meanwhile, Jixu 23 showed the lower rate of top biomass/storage root biomass (T/SR) at top cover stage (45 days after planting). On the other hand, in point of metabolism of sucrose and hexoses, and the formation of stored polysaccharide polymers, Shangshu 19 had sig- nificantly lower rate of sucrose/hexoses in the whole early growth phase, formed the greater sucrose concentration gradient be- tween leaves and roots, and had 1-kestose and nystose in roots at 15 and 30 days after planting. Its starch content in leaf was sig-