氮素形态对黄瓜幼苗光合特性及碳水化合物代谢的影响

用营养液培养的方法,研究了同一氮素水平不同氮素形态比例对黄瓜幼苗光合特性及碳水化合物代谢的影响。结果表明:与单一氮源相比,当NO3--N∶NH4+-N为75∶25时,黄瓜幼苗叶片叶绿素含量、净光合速率、气孔导度、胞间CO2浓度最大。单一供NH4+-N营养净光合速率高于单一供NO3--N。当NO3--N∶NH4+-N为50∶50时,可溶性糖、淀粉含量最大,单一NH4+-N最低。氮素形态对黄瓜根、茎、叶中的可溶性糖和叶片中的淀粉含量影响较大,但对根、茎中的淀粉含量影响较小。

Effects of Nitrogen Forms on Photosynthetic Characteristics and Sugar Metabolism of Cucumber Seedlings

A solution culture experiment was conducted to study the effect of NO3——N/NH4+-N ratio on the photosynthetic characteristics and sugar metabolism of cucumber seedlings under the condition of the same nitrogen level.The results showed that in comparison with single nitrogen nutrition,cucumber seedlings had the maximum chlorophyll content,net photosynthetic rate,stoma conductance and intercellular CO2 concentration when NO3——N/NH4+-N ratio was 75/25.In comparison with NO3——N treatment,NH4+-N treatment could increase the net photosynthetic rate.Soluble sugar and amylum content in cucumber seedlings were maximal when NO3——N/NH4+-N ratio was 50/50.Nitrogen forms significantly affected the soluble sugar content in the root,stem and leaf as well as the amylum content in the leaf,while had little effect on amylum content in the root and stem of cucumber seedlings.