不同氮水平下多效唑对食用型甘薯光合和淀粉积累的影响

在大田条件下，以北京553为试验材料，设置施低氮(N 120 kg hm^–2)和施高氮(N 240 kg hm^–2) 2个处理，每个处理下设置3个多效唑喷施浓度，研究不同施氮水平下喷施多效唑对食用甘薯光合特性和块根淀粉积累的影响。结果表明, 增施氮肥能够提高叶片叶绿素含量和光合速率，但减少干物质在块根中的分配率，降低块根淀粉积累速率，显著降低了单薯重、淀粉产量和鲜薯产量，降幅分别为8.0%、30.7%和20.5%；喷施多效唑可以提高叶片叶绿素含量和光合速率，促进碳水化合物向块根的运转，提高干物质在块根中的分配，提高淀粉积累速率，显著增加单薯重、淀粉产量和鲜薯产量，平均增幅分别为18.6%、32.5%和46.1%。说明在高氮条件下喷施多效唑对甘薯块根淀粉积累和产量的提高具有明显的调节作用。

Effect of Paclobutrazol under Different N-Application Rates on Photosynthesis and Starch Accumulation in Edible Sweetpotato

A field experiment was conducted to study the effects on leaf photosynthesis,root tuber starch accumulation and yield in edible sweetpotato(Ipomoea batatas L.Lam cv.Beijing 553)with two nitrogen treatments(120 and 240 kg ha-1 )and three paclobutrazol(PP333)spraying levels(0,100,and 200 mg ha-1 ).The result showed that increasing nitrogen application boosted Pn and chlorophyll content,reduced dry matter allocation in root tuber and starch accumulation rate,and significantly reduced the fresh weight per lump of root tuber(by 8.0%)and the starch yield and root tuber yield(by 30.7%and 20.5%).Spraying PP333 improved Pn and chlorophyll content,accelerated the transportation of carbohydrate from leaf to root tuber and enhanced its allocation in root tuber,the starch accumulation rate,significantly the fresh weight per lump of root tuber(by 18.6%)and the yield of starch and fresh weight of root tuber(by 46.1%and 32.5%).It was indicated that both starch accumulation and yield could be regulated by PP333 under high nitrogen application rate.