中文摘要：

【目的】甘薯[Ipomoea batatas（L.）Lam]属块根类淀粉作物,同时也是较典型＂喜钾＂作物,而甘薯种植区土壤缺钾十分普遍。同时,甘薯块根淀粉用途与其理化特性密切相关,因此,必须加强研究钾缺乏对甘薯块根淀粉理化特性的影响。【方法】选用3个不同钾效率型甘薯徐薯32（耐低钾与钾高效型）、徐薯18（中间型）与宁紫薯1号（不耐低钾与钾低效型）为材料,利用1980年设置的长期肥料定位试验田低钾（LK,氮磷处理）与正常钾水平（CK,氮磷钾处理）两处理,分析甘薯块根淀粉粒径大小与分布、热焓特性、糊化特性、吸湿性及膨胀力等特征指标差异。【结果】与正常钾相比,低钾胁迫改变甘薯块根中直链淀粉、支链淀粉、总磷、总脂肪和氮等主要组分,不同钾效率型甘薯间变化存在差异。甘薯淀粉粒径存在≤2.50μm、2.50—5.00μm和5.00—30.00μm等明显的3峰分布,低钾胁迫下淀粉粒径及其分布均发生变化,淀粉平均粒径降低,其中在体积分布中,徐薯32平均粒径减幅最小,宁紫薯1号降幅达显著水平（P〈0.05）,表面积与数目分布中差异不显著,而不同粒径的百分比、平均粒径与峰值（数目分布中无峰值）均有不同的变化,且这些变化在不同品种间也存在差异。淀粉糊化过程中的起始温度（T_0）、峰值温度（T_p）和热焓值（ΔH）普遍低于正常钾供应处理的相应指标,尤其宁紫薯1号在3个热特征值上的差异均达显著水平,其差异幅度大于徐薯32,3个甘薯品种最高粘度值、崩解值均明显下降,徐薯18与宁紫薯1号的最低粘度值、最终粘度值受低钾影响显著上升,而徐薯32的表现则相反。块根淀粉吸湿性均不同程度降低,徐薯18与宁紫薯1号降低达显著水平（P〈0.05）,徐薯32淀粉吸湿性变化较小,但其吸湿性值最高。淀粉膨胀力不同程度上升,宁紫薯1号增幅达显著水平（P〈0.05）,徐薯3

英文摘要：

[Objective] Sweetpotato （lpomoea batatas （L.） Lam） is a typical K-preferred starchy root crop. Potassium （K） deficiency （namely low potassium）, an important abiotic stress in plants, has become a major limiting element for obtaining crop high yield and good quality. However, in China, K deficiency in soils exists commonly in sweetpotato-growing areas. Sweetpotato starch utilization is closely related with its physico-chemical properties. The influence of low potassium on starch physic-chemical properties was investigated in an experiment conducted by using three sweetpotato cultivars with different potassium utilization efficiencies （KUE） in response to low potassium（K） field condition, aiming at providing reference for improving sweetpotato root properties and potassium utilization efficiency. [ Method ]Three sweetpotato cultivars with different potassium utilization efficiencies （KUE） were chosen and cultivated under different potassium field condition, including two treatments （low potassium treatment, LK, and normal potassium treatment, CK）. [Result] The results showed that under low K condition, the main components （amylose, amylopectin, nitrogen, total phosphorus and total lipid） in sweetpotato storage root starch changed to a certain extent. There were some differences among the three cultivars in the main components. Three distribution peaks in 42.50 μm, 2.50-5.00 μm and 5.00-30.00μm were observed in starch granule size obviously. The slight decrease was observed in the whole average granule size under low K, which of Xushu32 had the least decrease in volume distribution. However, there was a significant difference in decrease of average granule size of Ningzishul. The percentage, average granule size and peak value of different granule sizes in three distributions had some differences among three cultivars. Starch To （gelatinization temperature）, Tp （peak temperature） and AH （heat enthalpy） were basicially lower than that in CK treatment, and Ningzishul