スギ苗木の光合成速度と窒素含量に及ぼす庇陰と施肥の影響  [in Japanese] Effects of Light and Nitrogen Fertilization on Photosynthesis and Leaf Nitrogen Content in Cryptomeriajaponica Sapling  [in Japanese]

日林誌84:180〜183,2002異なる光強度と窒素施与量で育てたスギ苗木の,葉の窒素含有量と光飽和下の最大光合成速度との関係を調べた。面積あたりの最大光合成速度と窒素含量は生成光強度が高くなるにつれて増加し,窒素施与量が多いほど高い値を示した。このため,面晴あたりの窒素含有と最大光合成速度との間には高い正の相関が認められ,直線式で近似された。一方,乾重あたりの最大光合成速度は生育光強度が高くなっても増加しなかったが,窒素施与量が多いほど高い値を示した。このため,乾重あたりの窒素含量と最大光合成速度との間にも正の相関が認められたが,その相関は低かった。スギはにおける面積あたりの窒素含量は,光環境と土壌養分の双方が異なる場合でも最大光合成速度と常に直線関係にあることから,光合成速度を推定するための有効な指標になると考えられた。

J. Jpn. For. Soc. 84 : I80〜183, 2002 Relationship between light-saturated photosynthesis and leaf nitrogen content was studied in Cryptomeria japanica D. Don saplings growing under different light and nitrogen supply. Both light-saturated photosynthesis per area (P_max area) and leaf nitrogen per area (N_urea) increased with increasing light and nitrogen supply, P_max area was highly positively correlated with N_area. The slope of the linear regression between P_max area and N_area was 1.67 μmol CO_2gN^-1s^-1, which was low compared to that for other conifer trees previously described. Light-saturated photosynthesis per mass (P_max mass) did not increase with increased light, but increased with increasing nitrogen supply, P_max mass also positively correlated with leaf nitrogen per mass (N_mass), but the correlation coefficient was low. Since P_max area was highly correlated with N_area regardless of whether variation in N_area was due to light or nitrogen supply, this suggested that N_area would be a good index of photosynthesis in Cryplameria japonica.