Temporal variation in leaf nitrogen content in a Cryptomeria japonica canopy
2003
Kobayashi, H. (Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture) | Tashiro, N.
The temporal variation in leaf nitrogen content was investigated in an 8m tall Cryptomeria japonica canopy. Leaf nitrogen content (expressed on area basis) decreased with increasing leaf age. The nitrogen content of current leaves increased from June to October and then decreased thereafter. Nitrogen content of one-year-old leaves decreased gradually as the season progressed. There was no clear variation in leaf nitrogen content in two- and three-year-old leaves. The oldest leaf was three-year-old. and about half amount of the nitrogen was resorbed prior to leaf abscission. Nitrogen use efficiency was calculated from leaf life-span, resorption efficiency, and photosynthetic capacity. Photosynthetic capacity was estimated from leaf nitrogen content Nitrogen use efficiency of Cryptomeria japonica was intermediate to that of other conifer species previously described. We concluded that Cryptomeria japonica, which has short-life leaves and moderate resorption efficiency, increases nitrogen use efficiency with increasing photosynthetic capacity per unit leaf nitrogen.
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