Effects of shading stress on qualities of purple sweetpotato storage roots | 遮阴处理对紫甘薯块根品质的影响

Chinese. 【目的】研究不同基因型紫甘薯块根品质对不同遮阴程度的响应。【方法】以济薯18和Ayamuraski为材料,分别于块根膨大高峰期(栽后50―100 d),用不同透光度的黑色遮阳网设置遮光40%和遮光70%处理,对照(CK)为自然光处理,测定不同处理对块根干物质含量,总淀粉、直链及支链淀粉含量,淀粉积累速率,可溶性糖含量,蛋白质含量,全粉黏度仪参数及花青素含量的影响。【结果】遮阴处理下,紫甘薯块根中的干物质、总淀粉含量和淀粉积累速率比对照显著降低;遮阴处理不仅显著增加了济薯18直链淀粉含量、直/支比值,而且显著降低了济薯18全粉的高峰黏度、衰减值、回生值和峰值时间,遮阴下Ayamuraski块根的淀粉品质与济薯18相反;遮阴处理还显著提高了两个品种块根中的可溶性糖和可溶性蛋白含量,并随遮阴程度加大而增高;同时,紫甘薯的花青素含量和积累速率显著降低,济薯18的花青素积累对遮阴的反应比Ayamuraski更敏感。【结论】遮阴处理使紫甘薯的块根干物质、总淀粉含量和淀粉积累速率、花青素含量及不同膨大阶段的花青素积累量明显降低,同时遮阴处理下紫甘薯块根淀粉品质因品种而异。

English. 【Objective】 The study is to elucidate the effects of shading stress on root qualities of different genotypes purple-freshed sweetpotato. 【Method】 Using Jishu18 and Ayamuraski as materials, the plants were shaded with nets which had 40%, 70% transmittance of natural light at the root expanding peak period (50-100 d after transplantion), and the natural light was used as the control. Dry matter, starch content, amylose and amylopection content, starch accumulation ratio, soluble sugar content, protein content, the parameters of viscosity and anthocyanidin content of tuber root were determined. 【Result】 Results indicated that dry matter, total starch content and starch accumulation rate in the root of purple-freshed sweetpotato decreased significantly compared with the control under shading treatments. Shading treatments not only significantly increased amylose content and the ratio between amylose and amylopectin, but also significantly decreased peak viscosity, break down, set back and pasting temperature of Jishu18. However, the above-mentioned starch qualities of Ayamuraski were against to those of Jishu18. Soluble sugar and soluble protein increased significantly accompaned by rising of shading degree in two cultivars. In addition, anthocyanidin content and accumulation rate declined significantly under shading treatments, compared with Ayamuraski, the response to stress of Jishu18 was more sensitive. Researches showed that shading treatments changed root qualities of purple-freshed sweetpotao and displayed difference between varieties. 【Conclusion】 Shading treatments can significantly decrease dry matter, starch content and starch accumulation ratio, anthocyanidin content and anthocyanidin accumulation in tuber root of purple-freshed sweetpotato, while the quality of root starch varied in the different sweetpotato varities under shading treatments.