光度對大葉楠及香楠形質生長的影響

Effects of Different Light Intensities on the Morphological Growth of Large-leaved Nanmu and Incense Nanmu Seedling

本研究旨在探討不同光度對大葉楠及香楠苗木形質生長的影響，光度處理採人工遮陰，以不同密度的遮陰網調節網架內的相對光度，分別為相對光度10%、20%、40%、60%及全光對照等五種處理，測定各處理苗木的高生長、地徑生長、各部位乾物重、總葉面積及觀察葉片下表皮顯微構造，並分析葉部形態介量。試驗結果顯示，兩樹種之苗高及地際直徑生長量在不同處理間，差異性雖互異，唯大葉楠在相對光度60%及40%下有最大的生物量累積，而香楠則在相對光度60-20%處理為最佳，顯示此兩樹種皆為偏好適當遮陰的環境。乾物量的分配分析結果顯示，兩樹種在遮陰下皆會促使較多比率的乾物量分配至葉部。兩樹種葉部形態介量──葉面積比及比葉面積，在不同光度處理間皆呈顯著差異，經分析，兩介量之自然對數值與相對光度間具極顯著之相關性，且從迴歸式中可以推估，大葉楠在不同光度處理間的變化幅度較大，而香楠則在遮陰下呈現較大的形態介量值。由以上結果可得知大葉楠具適應光環境變化較大幅度的潛能，而香楠則屬於較偏陰的樹種。 The purpose of this study was to investigate the effects of different light intensities on the morphological growth of Large-leaved Nanmu(Machilus kusanoi Hay.) and Incense Nanmu(Machilus zuihoensis Hay. var. zuihoensis) seedlings. Light enviornments were cootrolled to 10%、20%、40% and 60% relative light intensities (RLI) by artificial shading and full sun-light as control. Seedling height、ground collar diameter、total le.af area、plant dry weight and micro-structures of leaf epidermis were measured, the parameters of leaf morphology were also investigated. The results exhibited that Large-leaved Nanmu seedlings grown under 60% and 40% of RLI and Incense Nanmu seedlings grown under 60-20% of RLI had the greatest biomass, which indicated those two species were adapted different light environment. The partition of dry mater strongly dispensed 10 leaves and significantly affected leaf morphology parameters by shade treaments. The regressions between relative light intensities and parameters indicated 1he characteristics of two species. Following the results mentioned above, we could conclude that Large-leaved Nanmu has greater potential to adapt varied light environments, and Incense Nanmu Lends to shade environment.

The purpose of this study was to investigate the effects of different light intensities on the morphological growth of Large-leaved Nanmu(Machilus kusanoi Hay.) and Incense Nanmu(Machilus zuihoensis Hay. var. zuihoensis) seedlings. Light enviornments were cootrolled to 10%、20%、40% and 60% relative light intensities (RLI) by artificial shading and full sun-light as control. Seedling height、ground collar diameter、total le.af area、plant dry weight and micro-structures of leaf epidermis were measured, the parameters of leaf morphology were also investigated. The results exhibited that Large-leaved Nanmu seedlings grown under 60% and 40% of RLI and Incense Nanmu seedlings grown under 60-20% of RLI had the greatest biomass, which indicated those two species were adapted different light environment. The partition of dry mater strongly dispensed 10 leaves and significantly affected leaf morphology parameters by shade treaments. The regressions between relative light intensities and parameters indicated 1he characteristics of two species. Following the results mentioned above, we could conclude that Large-leaved Nanmu has greater potential to adapt varied light environments, and Incense Nanmu Lends to shade environment.