대두(大豆) 수량(收量)이 우수한 은하(銀河), 방사(放射), 팔달(八達) 재배품종(栽培品種)을 광합성활성폭사선(光合成活性幅射線) ((PAR) 범위(範圍)에서 5본엽기(本葉期)(V5)에 엽온(葉溫)을 달리하여 광합성속도(光合成速度)와 호흡속도(呼吸速度)의 변화를 측정하였고, 품종별(品種別) 엽(葉)의 특성인 비엽중(比葉重)(SLW), 엽녹소함양(葉綠素含量)과 광합성(光合成)과의 관계를 조사한 결과(結果)는 다음과 같다. 1. 25℃에서 순광합성속도(純光合成速度)(Net Photosynthesis)는 은하(銀河) 21.5mgdm-2h-1, 방사(放射) 20.2mgdm-2hh-1, 팔달(八達) 18.5mgdm-2h-1이었다. 2. 전품종(全品種) 모두 엽온(葉溫) 25℃에서 광합성속도(光合成速度)가 가장 높았고 은하(銀河) 품종(品種)이 우수(優秀)했으며, 엽형(葉型)은 은하(銀河) (Long) 〉 방사(放射)(Oval) 〉 팔달(八達)(Round) 순서였다. 3. 엽(葉)의 호흡연도(呼吸連度)는 은하(銀河), 방사(放射), 팔달(八達)에서 15˚ 0.56mgdm-2h-1, 20℃ 0.79mgdm-2h-1, 25˚ 1,15mgdm-2h-1, 30℃ 1.37mgdm-2h-1였다. 4. 비엽중(比葉重)은 방사(放射)가 3.1mg/cm2이었고, 은하(銀河)와 팔달(八達)은 3.5mg/cm2이었으며 비엽중(比葉重)과 광합성(光合成)과는 유의성(有意性)이 인정되지 않았다. 5. 엽녹소(葉綠素) 함량(含量)은 은하(銀河)가 2.48μg/gF.W.으로 가장 높았고, 방사(放射)가 2.19μg/gF.W.이었고 팔달(八達)이 1.67μg/gF.W.로 가장 낮았으며 엽록소(葉綠素) 함량(含量)과 광합성(光合成)과는 유의성(有意性)이 인정되었다. 6. 광보상점(光補償點)은 15℃에서는 10μEm-2s-1로 모두 같았으나, 20℃에서 은하(銀河)는 12μEm-2s-1이었고, 방사(放射)와 팔달(八達)은 13μEm-2s-1이었다. 25℃에서는 은하(銀河)와 방사(放射)가 16μEm-2s-1이었지만 팔달은 18μm-2s-1이었고, 30℃에서는 은하(銀河)와 방사(放射)가 22μEm-2s-1이었지만, 팔달은 23μEm-2s-1이었다.

This study was conducted to investigate the Net photosynthesis and respiration rates among the varieties of Soybean(Eunha, Pangsa and Paldal that have high yields) at various leaf temperature and light intensity at the stage of V5. The relations between the Net photosynthesis rate and SLW(specific leaf weight) and chlorophyll content were also investigated. 1. Net photosynthesis rates at 25℃ were 21.5mgdm-2h-1 in cv. Eunha, 20.2mgdm-2h-1 in cv. Pangsa and 18.5mgdm-2h-1 in cv. Paldal. 2. Most cultivars of Soybean showed the maximum rates of Net photosynthesis at 25℃, especially in cv. Eunha. Also Net photosynthesis rates differed depending on the leaf shape. Long leaf shape(cv. Eunha) was better than round leaf shape(cv. Paldal) in Net photosynthesis rate. 3. Respiration rates of leaves in Eunha, Pangse and Paldal were 0.56mgdm-2h-1 at 15℃, 0.79mgdm-2h-1 at 20℃ 1.15mgdm-2h-1 at 25℃ and 1.37mgdm-2h-1 at 30℃. 4. Specific leaf weight were 3.1mg/cm2 in Pangsa, 3.5mg/cm2 in Eunha and Paldal. No signlficant difference were showed in net photosynthesis rates and specific lear weight. 5. Leaf chlorophyll content were 2.48μg/gF.W. in Eunha, 2.19μg/gF.W. in Pangsa and 1.67μ/g F.W. in Paldal. Significant difference were showed in Net photosynthesis rates and Leaf chlorophyll content. 6. The estimated compensation points at which net photosynthesis approached zero were 10μEm-2s-1 in Eunha, Pangsa, and Palda at 15℃. The compensation point in cv. Eunha at 20℃ was 12PμEm-2s-1 while 13μEm-2s-1 in Pangsa and Palda. The compensation point in cv. Paldal at 25℃ was 18μEm-2s-1 while 16μEm-2s-1 in Eunha and Pangsa. The compensation point in cv. Palda at 30℃ was 23μEm-2s-1 Palda while 13μEm-2s-1 in Eunha and Pangsa.

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