京都大学北海道演習林におけるヤチダモの育林学的研究 第IV報 : ヤチダモ稚樹の耐陰性について

Abstract

(1) 庇陰格子 (照度5%, 15%, 60%) を使つてヤチダモ稚樹の庇陰に対する成長上及び栄養生理上の影響を調べた｡ (2) 幹重量成長量は, 60%区>100%区>15%区>5%区となつて, 60%区は対照区よりも良好である｡ (3) 肥大成長量は大体乾重量と同様な傾向にあり60%区が最大である｡ (4) 上長成長は, 60%区>15%区>100%区>5%区となつて, 60%区で最大であるが, 15%区も対照区より良好である｡ (5) 有機化合物中, 窒素代謝に対する庇陰の影響は葉部の蛋白態窒素及び可溶性窒素に現われ前者は15%, 5%区に, 後者は60%及び100%区に多量に存在した｡ (6) 葉部炭水化物の含量は60%区>100%区>15%区>5%区となつて, 60%区で最多となる｡ (7) 光合成能力は, 単糖類の出現量から推して, 100%区が最も旺盛であることがわかつた｡ 以下60%>15%>5%となる｡ (8) 葉部P2O5及びK2O含量は光線量の増加に伴なつて増大の傾向にある｡ これに反しCaO及びSiO2は減少の傾向が認められた｡ (9) 葉部組織の灰分代謝は光線量の不足に伴なつて旺盛になるようである｡ (10) 以上の栄養生理上の事実は, 陰, 陽両葉における過去の文献と良く一致しており, 庇陰下における樹木の葉部生理機能も, 全く陰陽両葉における生理機能と同一であることが推定できた｡ (11) 各種, 4段階の光線量のもとで試験を実施したが, 成長量及び栄養生理面から眺めれば, 100%, 60%区, 及び15%, 5%区の2区に大別できるようである｡ (12) 本研究の結果, ヤチダモ稚樹は, 60%前後の光線で生育可能であつて, それ以下では被圧を受け漸次生長量の減退を来たすものと思われる｡

These investigations reported here were performed to make clear the shade resistances of Yachidamo (Fraxinus Mandshuriea Rupr) reported here young tree (4 years old) from the standpoint of growth, functional changes of nutrition and plant physiology. Then the light intensity using adjusted by 3 shade lattices (the light intensity; 60%, 15%, 5%). We also supplied the control section (100% light intensity) besides 3 shade lattices. The followings are the results of these investigations, A. The changes of growth by light intensity; The dry matter weight of the leaves, stems and roots in 60% light intensity was much greater than that of the others. They changed in the following order: 60%, 100%, 15% and 5%. The diameter growth showed almost the same tendency as the dry matter weights. But the height growth changed as follows; 60%, 15%, 100%, and 5%. It was a distinctive character that the height growth in the section of the 15% light intensity was better than that in the control section (light intensity 100%). These investigations summarized that the plot of 60% light intensity showed the best growth in dry matter weight, diameter growth and height growth, and the plot of 5% light intensity the worst growth. B. The changes of the organic matter contents by light intensity; The shade effects for the nitrogenous metabolism in leaves appeared as following Albuminous nitrogen was in a large quantity both in the 15% and 5% light intensity piot and soluble nitrogen was much both in the 100% and 60% light intensity plot. Conjecturing the faculty of photosynthsis from the mono-saccharide contents in leaves, it was most vigorous in the section of 100% light intensity. This faculty of the other section decreased in proportion to declining of the light intensity. C. The changes of the inorganic matter contents by light intensity; Phosphorus and potassium contents in leaves increased with the enlargement of the light intensities, on the other hand calcium oxide (CaO) and silicon dioxide (SiO2) decreased with them. The ash metabolism in leaves was more vigorous with th declining of the light intensity. From B and C, we understood that the physiological faculty of this tree under the shade was almost the same as that of the shade leaf and the sun leaf. D. Considering the changes of the growth, organic and inorganic matter contents, the Yachidamo young tree in the 60% light intensity grew much better than others. In the 5% light intensity it grew worse.