Shoot biomass growth is related to the vertical leaf nitrogen gradient in Salix canopies.
Shoot biomass growth is related to the vertical leaf nitrogen gradient in Salix canopies.
复制标题
芽生物量的生长与柳树冠层的垂直叶氮梯度有关。
作者：
M. Weih;Ann
植物冠层优化模型预测，叶片氮（N）在冠层中的分布将平行于垂直光梯度，许多物种的研究已经证实了这一预测。此外，据预测，对于一个给定的冠层叶面积，低的垂直消光系数将促进快速增长。因此，理想的冠层的快速增长的植物应结合联合收割机高叶面积指数与低消光系数，后者反映在一个平坦的垂直叶片N梯度整个冠层。根据数据从实验柳立场（6个品种）在瑞典中部的农业用地上生长，我们测试的假设，即新梢生长与垂直叶氮梯度的混合柳树繁殖的生物量生产，这可能会对柳育种。树木改良研究需要筛选大量植物的生长相关性状，但通过化学分析评估冠层叶片氮梯度是昂贵的，耗时的和破坏性的。分析方法的一种替代方法是用光学叶绿素计（SPAD方法）非破坏性地估计叶片N梯度。在这里，我们提供了一个具体的校准解释SPAD数据测量杂交柳树生长在肥沃的农业用地上的生物质种植园。SPAD观测结果表明，6个柳品种地上部生物量生长与冠层内叶片氮素垂直梯度呈显著负相关（r（2）= 0.88）。
Plant canopy optimization models predict that leaf nitrogen (N) distribution in the canopy will parallel the vertical light gradient, and numerous studies with many species have confirmed this prediction. Further, it is predicted that for a given canopy leaf area, a low vertical light extinction coefficient will promote rapid growth. Therefore, the ideal canopy of fast-growing plants should combine high leaf area index with a low light extinction coefficient; the latter being reflected in a flat vertical leaf N gradient throughout the canopy. Based on data from an experimental Salix stand (six varieties) grown on agricultural land in central Sweden, we tested the hypothesis that shoot growth is correlated with vertical leaf N gradient in canopies of hybrid willows bred for biomass production, which could have implications for Salix breeding. Tree improvement research requires screening of growth-related traits in large numbers of plants, but assessment of canopy leaf N gradients by chemical analysis is expensive, time-consuming and destructive. An alternative to analytical methods is to estimate leaf N gradients nondestructively with an optical chlorophyll meter (SPAD method). Here we provide a specific calibration for interpreting SPAD data measured in hybrid willows grown in biomass plantations on fertile agricultural land. Based on SPAD measurements, a significant and inverse relationship (r(2) = 0.88) was found between shoot biomass growth and vertical leaf N gradient across canopies of six Salix varieties.