结薯数差异显著的甘薯品种生长前期根系特性及根叶糖组分比较

摘要

选用结薯数差异显著的甘薯品种商薯19和济徐23,于2013年和2014年分别在大田和盆栽条件下调查生长前期根系生长发育情况,测定根叶糖组分,分析其变化规律及其与单株有效薯块数形成的关系。结果表明,与济徐23相比较,商薯19发根缓苗迅速,整个生长前期均较为侧重吸收根系建成,且秧苗栽后15 d和30 d地上部和整个根系生物量比值(T/TR)相似；而济徐23较早完成不定根的发生(秧苗栽后15 d)和不定根向块根的分化建成(秧苗栽后30 d),封垄期(秧苗栽后45 d)具有较小的地上部和块根生物量比值(T/SR)。2个品种在生长前期根叶中蔗糖、己糖代谢和贮藏糖类多聚物的形成具有显著差异,其中商薯19整个生长前期比济徐23的根系蔗糖/己糖比率显著低,在块根分化建成过程中根叶间具有较高的蔗糖浓度梯度,且根系中存在2种低果聚糖(蔗果三糖和蔗果四糖),秧苗栽后30、45 d叶片淀粉含量显著低；而济徐23在块根分化建成过程中根系仅有蔗果四糖,且与商薯19比,封垄期根系蔗糖/可溶性总糖比率相似而根系蔗糖/淀粉比率显著低。2013年和2014年的大田试验均表明,封垄期商薯19具有显著多的单株有效薯块数和显著高的单株有效薯块鲜重(F=10.71, P=0.0170；F=13.97, P=0.0212),而收获时商薯19具有显著多的单株有效薯块数和显著高的块根产量(F=353.89, P<0.0001； F=88.94, P<0.0001),济徐23具有显著高的平均单薯鲜重(F=10.32, P=0.0124)。%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-nificantly lower than that of Jixu 23 at 30 and 45 days after planting. Meanwhile, Jixu 23 only had Nystose in roots before storage root formation, with significantly lowest rate of sucrose/starch when the rate of sucrose/total soluble sugar was similar to that of Shangshu 19 at 45 days after planting. A two-year field trials (2013–2014) were performed to investigate yield-contributing traits and the fresh storage root yield at top cover stage and harvest period, in which, Shangshu19 showed the more valid storage roots per plant, higher valid storage root fresh weight per plant or storage root at top cover stage and harvest period, meanwhile, Jixu23 had significantly higher average fresh weight per storage root.