作 者 ：安慧,上官周平
期 刊 ：生态学报 2007年 27卷 4期 页码：1323~1332
Keywords:root restriction, Forsythia suspensa, gas exchange parameters, nitrogen allocation, nitrogen application,
摘 要 ：在植物生长箱通过溶液培养试验，从叶片光合气体交换参数、叶绿素含量及其荧光参数等方面来探讨不同氮素浓度条件下根域体积对连翘幼苗光合生理特性及生长的影响，并采用15N示踪技术对不同氮素浓度条件下根域体积对连翘幼苗体内氮素转运进行了研究。结果表明：低氮（LN）处理幼苗的地上部和根系干物质重较高氮（HN）处理的高，根域限制对地上部和根系干物质重的影响不同，LN处理幼苗地上部和根系干物质重在低根域体积（10cm×10cm×15cm，LR）处理均较高根域体积（20cm×10cm×15cm，HR）处理的低，HN处理的幼苗响应情况有所不同。LN处理幼苗的叶片净光合速率（Pn）和叶绿素含量较HN处理的高；LN处理幼苗Pn 和气孔导度（Gs）在LR处理较HR处理的高，而HN处理幼苗的Pn 和Gs 随根域体积变化规律与LN处理相反，LN和HN处理叶绿素含量随根域体积变化规律与Pn相反。LN处理幼苗的PSⅡ 最大光化学量子效率（Fv/Fm）和PSⅡ电子传递量子效率（ФPSⅡ）均较HN处理的高，不同供氮处理下LR处理幼苗的Fv/Fm 均较HR处理的高；而ФPSⅡ的变化规律相反。不同供氮处理时，LR处理幼苗的光化学猝灭系数（qP）均较HR处理的低，而非光化学猝灭系数（qNP）的变化规律相反，LN处理幼苗的qNP较HN处理的高（p<0.05）。不同供氮处理时，LR处理幼苗根系和地上部氮含量均较HR处理的低，LN处理幼苗根系和地上部氮含量较HN处理的低，幼苗根系和地上部氮含量随氮素浓度变化差异显著（p<0.05）。LN处理幼苗根系吸收15N在根系和叶片的分配率均较HN处理的低，而根系吸收15N在枝和茎的分配率呈相反变化规律。根系吸收氮在叶片和枝的分配率分别为7%～10%和7%～12%，叶片和枝生长需要的氮素主要由其内源N库提供。
Abstract:The photosynthetic characteristics, nitrogen (N) transport and root-zone volumes of Forsythia suspensa seedlings cultivated in a plant growth chamber with different N concentration treatments were studied. The results showed that the dry weights of shoots and roots of Forsythia suspensa seedlings under low N treatment were higher than that under high N treatment. The effects of root restriction on the shoot and root dry weights of Forsythia suspensa seedlings under low N treatment were different, and the seedlings with low root restriction (LR, 10cm×10cm×15cm) had lower shoot and root dry weights than that with high root restriction (HR, 20cm×10cm×15cm). The net photosynthetic rate (Pn) and chlorophyll content of Forsythia suspensa seedlings under low N treatment were higher than that under high N treatment. Under low N treatment, the LR seedlings had higher Pn and stomatal conductance (Gs) than HR seedlings, however, the HR seedlings under high N treatment had higher Pn and Gs than LR seedlings. The effects of root restriction on chlorophyll content of Forsythia suspensa seedlings under both N treatments were different from that on Pn Comparatively, the maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency of PSⅡ (ФPSⅡ) and non-photochemical quenching coefficient (qNP) of Forsythia suspensa seedlings under low N treatment were higher than that under high N treatment. And the LR seedlings under low or high N treatment had higher Fv/Fm and qNP but lower ФPSⅡ and photochemical quenching coefficient (qP) than HR seedlings. The N contents in roots and shoots of Forsythia suspensa seedlings under low N treatment were lower than that under high N treatment. And the LR seedlings under low or high N treatment had lower N contents in roots and shoots than HR seedlings. The percentages of 15N allocation in roots and leaves of Forsythia suspensa seedlings under low N treatment were lower than that under high N treatment, however, the percentages of 15N allocation in branches and stems of seedlings under low N treatment were higher than that under high N treatment. The allocation percentages of N absorbed by roots in leaves and branches were 7%-10% and 7%-12% respectively, and the nitrogen demand for leave and branches growth was mainly met by internal N stocks.