墾丁熱帶森林六種樹苗生長性狀及光合作用對光量的可塑性

Morphological and Photosynthetic Plasticity to Light Regimes in Seedlings of Six Tropical Tree Species at Kenting, Taiwan

郭耀綸(Yau-Lun Kuo) ； 楊月玲(Yeh-Lin Yang) ； 吳祥嗚(Shang-Ming Wu)

《台灣林業科學》 14卷3期 (1999/09) Pp. 255-273

https://doi.org/10.7075/TJFS.199909.0255

摘要

本研究藉透光率100%，65%，35％及10% 4種人工遮蔭處理，探討台灣樹蘭、軟毛柿、象牙樹、火筒樹、枯里珍及鐵色6種苗木光合特性及生長性狀對不同光量的反應及可塑性。經兩年試驗，光量由10％提高到35％可顯著促進苗木生物量，6種中有5種已達最大值，軟毛柿則在65％光量才達最大生物量。除鐵色外，強光會抑制樹高的生長，而火筒樹和象牙樹的樹高隨光量減低而顯著增高。各樹種在10％低光處理有最大的葉重率、葉面積率及葉綠素總量，而根重率、比葉重、光補償點及暗呼吸率則隨光量提高而增加。比較生長在65％及10％苗木的六項生長性狀，發現枯里珍和軟毛柿的形態對光量的可塑性最高。各樹種光合可塑性與光合潛力有顯著正相關，光飽和點及最大光合率較高的樹種會有較高的光合可塑性，以台灣樹蘭的光合可塑性最高而鐵色最低。苗木四季平均淨光合率、總葉面積及此兩項的乘積，可解釋不同樹種在不同處理苗木生物量的變異。各樹種在低光下形成的蔭葉的光合潛力仍很高，除了鐵色，其它5種的光合潛力可達7.8μmol m^(-2)s^(-1)以上。

關鍵字

生物量 ； 葉面積 ； 光補償點 ； 光合潛力

並列摘要

Morphological and physiological plasticities to various light regimes were compared in seedlings of Aglaia formosana, Diospyros eriantha, Maba buxifolia, Leea guineensis, Antidesma pentandrum var. barbatum, and Drypetes littoralis. Potted seedlings of these species were grown under 10%, 35%, 65%, and 100% Light regimes. After 2-yr growth, all species except Diospyros had reached the highest biomass when light level was raised from 10% to 35%, with no significant increases at either 65% or 100%. Diospyros, on the other hand, did not reach the highest boimass until the light level reached 65%. High light inhibited height growth of all species except Drypetes. As light intensity decreased, plant heights of Leea and Maba increased significantly. Seedlings grown under 10% light had the highest leaf weight ratio, leaf area ratio, and total chlorophyll contents. On the contrary, root weight ratio, leaf weight per area, light compensation point, and dark respiration increased as light level increased. When comparing 6 growth traits of seedlings under the 65% and 10% light regimes, Antidesma and Diospyros showed the highest capacity for morphological plasticity. Photosynthetic plasticity was found to be closely related to photosynthetic capacity. Species with higher light saturation points and photosynthetic capacities had higher photosynthetic plasticities. Among these 6 species, Aglaia and Drypetes had the highest and the lowest capacity for photosynthetic plasticity, respectively. Variations in seedling biomass could be explained by their total leaf area, seasonal mean net photosynthetic rates, and the products of these 2 variables. Except for Drypetes, leaves of all other species grown with a 10% light regime still had photosynthetic capacity higher than 7.8 μmol m^(-2)s(-1), which is a relatively high rate per se.

並列關鍵字

biomass ； leaf area ； light compensation point ； photosynthetic capacity