甘薯叶光合特性与块根主要性状对氮素供应形态的响应

为探明甘薯叶光合特性与块根主要性状对不同氮素形态供应的响应特点，以徐薯18为研究对象，在盆栽条件下，设置铵态氮、 硝态氮和酰胺态氮3种氮素处理，研究不同形态氮素供应对甘薯叶光合特性、 块根产量与品质性状影响的差异。结果表明，在移栽后30 d 和50 d 时，酰胺态氮处理叶片叶绿素含量(CCI)为最高，70 d时，铵态氮处理的CCI最高；铵态氮处理显著提高叶片的光合速率与有效辐射(PAR)；氮素处理明显提高甘薯块根产量，其中，铵态氮处理较硝态氮和酰胺态氮处理块根产量分别增加10.6%与17.2%，增产显著(P0.05)；铵态氮处理提高甘薯块根的淀粉率和蛋白质含量，而酰胺态氮处理增加可溶性糖和还原糖含量；铵态氮处理有利于增加甘薯淀粉最高粘度值（PKV）、 崩解值（BDV）和回复值（CSV），而硝态氮处理促进最低粘度值（HPV）和最终粘度值（CPV）的上升。

Responses of nitrogen supply forms on leaf photosynthetic characteristics?and root characters of sweetpotato

In order to study the effect of different nitrogen supply forms on leaf photosynthetic characteristics, root yield and quality of sweetpotato, a pot experiment was conducted with three nitrogen forms, NH+4-N［(NH4)2SO4)］, NO-3-N(NaNO3) and CONH4-N(urea) using sweetpotato cv. Xushu18. The results showed the chlorophyll contents(CCI) with CONH4-N were the highest after 30 d and 50 d of planting, while CCI with the NH+4-N was the highest in 70 d. The photosynthetic rate and photosynthetically active radiation(PAR) under the NH+4-N treatment are the highest. TheNO-3-N treatment could promote more photosynthesis of sweetpotato leaves, and the yield under the NH+4-N treatment is higher than those of the NO-3-N and CONH4-N treatments, increased by 10.6% and 17.2%, respectively. There are significant differences(P0.05) between the NH+4-N treatment and other treatments. Meanwhile, the starch content and protein content of sweetpotato roots under theNH+4-N treatment are the highest, while the soluble sugar content and reducing sugar content under the CONH+4-N treatment are the highest. The NH+4-N treatment promotes the values of peak viscosity, breakdown and consistence of sweetpotato starch, and theNO-3-N treatment promotes the values of through viscosity and final viscosity.