七種林木在不同季節達最大光合作用率時的葉位 及葉齡

Seasonal Variations of Leaf Order and Leaf Age when Reaching Maximum Photosynthetic Rate in Seven Tree Species

郭欣儀(Shin-Yi Kuo)

指導教授 ： 郭耀綸

國立屏東科技大學/農學院/森林系所/碩士(2015年)

https://doi.org/10.6346/NPUST.2015.00108

摘要

過去研究人員在測定光合作用率時，通常是選取形態新近成熟之葉片，或是選取位於枝條前端第3~5個葉位的葉片供測定，認為此處的葉片有較高的淨光合作用率。然而，上述經驗法則並無量化的數據供驗證。本研究目的為比較同一樹種在不同季節葉片達最大光合作用率(Amax)時的葉位是否不同，並探討最大光合作用率的葉片在枝條何處。本研究在屏科大森林系苗圃選擇陽性樹種構樹及臭娘子，中等耐陰樹種紫黃、烏心石及銀葉樹，耐陰樹種白樹仔及鐵色共7種，每種3~4株樣木，各樹種均選定10個枝條，連續標定新生葉片。樣木高度在1.5~3.0 m範圍。從2013年8月開始分別測定一年四季各葉位葉片的淨光合作用率，可得知各季同一枝條出現最大淨光合作用率之葉片的葉位及葉齡，並計算各樹種不同季節的長葉速度。結果發現於春夏兩季，構樹、紫黃、銀葉樹及鐵色達Amax時的葉片以形態成熟葉的第4~6葉位居多，而臭娘子、烏心石及白樹仔以第3葉位居多。在秋冬兩季除了紫黃之外，其餘6樹種達Amax的葉片以形態成熟葉的第2~4葉位居多。研究發現同一樹種不同季節達Amax的葉位，會受該季節葉片生理成熟的葉齡，及該季節長葉速度，兩者共同影響。某樹種在達Amax需時較短的季節，達Amax的葉片會排列在枝條較前端。若某樹種在長葉速度較快的季節，達Amax的葉位會在枝條較後端。然而，在冬季長葉速度較慢，令生理成熟葉片出現在枝條較前端。此外，本研究也發現同一樹種一年四季中以春季或夏季達Amax的葉齡最短；有5種達Amax葉齡在冬季最長，但銀葉樹及鐵色達Amax的葉齡卻是以春季最長。在長葉速度方面，構樹、臭娘子及紫黃同一枝條春夏兩季每個月可長5~9片新生葉片，烏心石及銀葉樹均約為3片，白樹仔及鐵色則為2~3片。綜合供試7樹種的結果，本研究發現同一枝條達Amax的葉片大多在形態成熟第3~5葉位的葉片。此外，本研究供試樹種達最大光合作用率的葉片，都是在枝條前端1/4的部分，而不是在枝條中間部位。
關鍵詞：葉齡、長葉速度、葉位、最大光合作用率、季節變化

關鍵字

葉齡 ； 長葉速度 ； 葉位 ； 最大光合作用率 ； 季節變化

並列摘要

In the past, researchers normally chose newly matured leaves, or leaves at the 3~5 sprouting orders from top of a branch, to measure the photosynthetic rate of a plant. However, this measuring method which based on past experiences did not provide quantitative data for references. The objectives of this research were to investigate the differences of maximum photosynthetic rate (Amax) in different leaf orders of a species during various seasons, and at which leaf order does the Amax occur. Seven species of various shade tolerance classes, including shade-intolerant species Broussonetia papyrifera and Premna serratifolia, moderate shade-tolerant species including Margaritaria indica, Michelia formosana and Heritiera littoralis, shade-tolerant species Gelonium aequoreum and Drypetes littoralis were selected for this study. Ten branches from 3~4 saplings within the range of 1.5~3.0 m in height of each species were tagged for their newly sprout leaves. Photosynthetic rates of each leaf during the four seasons were measured since August, 2013. With these obtained informations, we then knew the leaf order at the branch and leaf age when it reached Amax in various seasons, and thereby calculated leaf sprouting rates in different seasons. Our results showed that, during spring and summer seasons, leaves which had reached Amax were mostly at the 4th~6th leaf orders of morphologically matured leaves in B. papyrifera, Mar. indica, H. littoralis, and D. littoralis, while they were mostly at the 3rd leaf order in P. serratifolia, Mic. formosana, and G. aequoreum. During autumn and winter seasons, leaves which had reached Amax were mostly at the 2nd~4th leaf order in all species besides Mar. indica. We found that the leaf order at which a leaf reached Amax in various seasons was influenced by both the leaf age when physiologically mature and the leaf sprouting rate during that season. A species would have leaves reached Amax at an front position of a branch when a shorter time is needed for reaching Amax. During a faster sprouting season, leaf order of reaching Amax would be at a position relatively away from the branch tip. However, leaf sprouting rates were slower during winter season such that leaves of physiologically mature would be at an front position. In addition, we also found that leaf age of leaf reaching Amax were the shortest during spring or summer seasons. Five species showed the longest leaf age of leaf reaching Amax during winter season, while that of H. littoralis and D. littoralis were during the spring season. For leaf sprouting rates, B. papyrifera, P. serratifolia, and Mar. indica grew 5~9 new leaves per month during spring and summer seasons; Mic. formosana, and H. littoralis grew 3 new leaves; and G. aequoreum and D. littoralis grew 2~3 leaves. To summarize results from the above 7 species, we found that leaves of a same branch reached Amax mostly at 3~5 leaf orders. In addition, leaves reached the highest photosynthetic capacity were at the front 1/4 position and not at the middle position of a branch.
Keywords：leaf age, leaf generating speed, leaf order, maximum photosynthetic rate, seasonal variation.

並列關鍵字

leaf age ； leaf generating speed ； leaf order ； maximum photosynthetic rate ； seasonal variation

參考文獻

顏君靜 (2013) 不同耐陰性樹種葉片達最大光合潛力葉序之比較。國立屏東科技大學森林系碩士論文，62頁。

游智偉 (2006) 不同光量及養分對四種臺灣原生闊葉樹苗光合作用及葉綠素螢光反應之影響。國立台灣大學森林環境暨資源學系碩士論文，67頁。

陳淑真、熊同銓 (2003) 玫瑰葉齡及品種對於光合作用之影響。華岡農科學報 11: 73-84。

翁韶良、陳忠偉、方懷聖、黃士元、翁仁憲 (2011) 在不同溫度與光度下桃實百日青之光合速率與葉綠素螢光特性。台灣生物多樣性研究 13(1): 71-83。

葉嬋嫻、施慶芳、周雪美 (2003) 台灣欒樹光合作用之研究。生物學報 38(1): 27-36。