Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/20951
標題: 根溫處理對溫室洋香瓜氮代謝之影響
Effects of Root Temperature on the Nitrogen metabolism of muskmelon (Cucummis melo L.)
作者: 郭建榮
Guo, Jain-Rong
關鍵字: root temperature;根溫;nitrogen metabolism;muskmelon;氮代謝;洋香瓜
出版社: 植物學系
摘要: 
以水氣耕栽植之溫室洋香瓜( Cucummis melo L. )為材料,用循環水
槽控制培養液溫度於15度,25度,及35度,藉以探討根溫與溫室洋香瓜根部
及地上部之生長,生理機能及氮代謝 酵素活性關係.結果顯示溫室洋香瓜
於15度低液溫下生長,根部受低溫逆境影響,導致蒸散速率,水分與養分的
吸收速率,葉片光合作用能力及碳同化作用( Rubisco活性 )皆下降,因此,
碳骨架與能量來源受到限制而造成植物生長受抑制. 植物的固氮作用
是亟需耗能的反應,且須利用光合產物的碳架來固定氨基.低溫處理株根部
之呼吸作用會下降,能量來源不足,致使固氮作用的酵素活性( 包括NR,
NiR, GS, GOGAT )偏低.植株為維持正常生理代謝上氮源的需求,低溫處理
株轉移部份的硝酸至地上部葉片中進行固氮作用,因此,低溫處理株葉片的
固氮酵素活性會高於其他根溫處理株.25度,35度根溫處理株之固氮作用主
要則由根部組織進行.因此,固氮酵素活性較低溫處理株高. 結果期,植
物生合成產物會大量輸送至果實,為有效運送含氮物質,溫室洋香瓜以
amide 中的Asparagine(Asn)為主要氮源輸送的有機形式.Glu和Gln為
植物體轉換成Asn的前驅物,因此植物可將其他組織蛋白水解的氨基酸,利
用GS/GOGAT cycle的進行,轉換成Glu和Gln的 形式,提供給Asn
synthetase轉換成Asn的形式,以便運送至果實中,而有利於植物體內氮源
之再分佈.

The aim of this study was to elucidate the effects of the
different root temperatures (35, 25, 15 degree )on growth and
nitrogen metabolism of muskmelon (Cucummis melo L.) under the
hydroponic system. Examinations on the changes of the
physiological characterics under different root temperatures
including biomass, photosynthetic rate, respiration rate,
stomatal conductance, content of free amino acid, soluble, and
the enzyme activities of NR, NiR, GS, GOGAT,GDH, and Rubisco.
The results were summarized as follows: The decreasing of
root temperature resulted in the decreasing of photo-synthetic
rate, respiration rate, Rubisco activity and total dry weight in
leaves. The lowest root temperature inhibited the absorpting of
nutrition onplant growth. Undeer 15 degree root temperature
treatment, the content of total solubleprotein was lowest in
both roots and leaves. Furthermore, the activities ofNR and NiR
were lowest in root, but highest in leaves. The reason may be an
increasing in the flow rate of nitrate into leaves. Therefore,
the assimilation of nitrogen increasing in leaves on low
temperature. In higher plants, ammonina is mainly assimilated by
GS and GOGAT pathway which produces glutamine andglutamate. The
low temperature inhibited GS/GOGAT activities in roots.
Thereforethat is favorable to ammonium assimilation in leaves.
Our results showed that indeed asparagine was the highest
content among 20amino acids in leaves and roots of all root
temperature treatments. In fruit growth period, the transmitting
of asparagine is very important from leaves and roots. For this
reason, changes in amino acids content and composition of sink
(fruit) was more important than the effect of root temperature.
URI: http://hdl.handle.net/11455/20951
Appears in Collections:生命科學系所

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