Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/20661
標題: 缺水處理對番木瓜葉片光能利用及抗氧化系統之影響
Effects of drought stress on light energy utility and antioxidant system of papaya(Carica papaya L.)leaf
作者: 王志恭
Wang, Jhy-Gong
關鍵字: papaya;番木瓜;drought;light energy utility;antioxidant system;缺水;光能利用;抗氧化系統
出版社: 植物學系
摘要: 
本研究以台農五號番木瓜(Carica papaya L. cv. Tainung No. 5)為試
材,藉Polyvinyl formal(PVF)做為自動供水裝置,以三種PVF長度控制
不同程度供水處理,探討長期缺水處理對番木瓜葉片生理代謝、光能利用
及抗氧化系統的影響。結果顯示,對照組、中度缺水處理組及缺水處理組
葉片水分潛勢分別為-1.12、-1.37及-1.60 MPa,滲透潛勢分別為-1.46
、-1.57及-1.68 MPa。分析葉片溶質發現,主要是以蔗糖當為滲透調節物
質,缺水處理下,葉片累積大量蔗糖,以增加葉片的可溶性糖類含量,使
葉片滲透潛勢下降,水分潛勢降低,以因應缺水逆境。缺水處理使葉片膨
壓降低及光合成速率下降,導致葉面積減少;且氣孔導度因缺水處理下降
,而使蒸散速率降低,導致缺水處理組之吸水量減少。缺水處理組之葉片
光合成速率、氣孔導度、Rubisco活性及qP皆下降,而qN及葉綠素含量皆
增加,分析後發現,光能轉換效率及氣孔因子是影響光合成速率降低的主
因,非氣孔因子及葉綠素含量對光合成速率影響程度不明顯。此外,
energy dissipation及胡蘿蔔素含量皆隨著缺水程度增加而增加,表示胡
蘿蔔素可扮演消除光反應系統因缺水引起能量過多的角色,減少活性氧產
生;而抗氧化物質含量(ascorbate及glutathione)及抗氧化酵素活性(
SOD、APX、MDHAR、DHAR及GR)皆隨著缺水程度增加而增加,促使抗氧化
系統能力增加,以增加消除活性氧的速率,降低活性氧的傷害。由於胡蘿
蔔素及抗氧化系統共同發揮光保護作用,故缺水處理下,葉片的脂質過氧
化作用及離子滲漏程度僅輕微增加,而PSII光化學效率(Fv/Fm)亦僅受
到輕微抑制。綜合以上可知,供試番木瓜的葉片可適應本研究設計之缺水
程度,並對缺水所引起的氧化逆境亦具有抗性。

This study investigates the light energy utility and antioxidant
system of leaf of papaya (Carica papaya L. cv. Tainung No. 5)
under long-term drought stress set by different length of
polyvinyl formal (PVF). The leaf water potential of control,
mild drought stress, and drought stress is -1.12, -1.37, and
-1.60 MPa, respectively. Leaf osmotic potential is -1.46, -1.57,
and -1.68 MPa, respectively. An increased sucrose as
osmoregulatory solute was detected in the papaya leaf under
drought stress which leads tothe decrease of osmotic potential
and water potential contributing to the survival under drought
stress. The leaf pressure potential and photosynthesis rate (PR)
both are decreased under drought stress, leading to the leaf
area reduction.. The decreased transpiration rate is caused by
the reduction of stomatal conductance (SC) under drought stress.
Under drought stress, the water absorption of papaya is
decreased due to both the reduction of leaf area and
transpiration rate.All of PR, SC, Rubisco activity, and qP are
increased under drought stress, but qN and chlorophyll content
are increased. The effects of light energy conversion efficiency
and stomatal factor on photosynthesis rate are larger than non-
stomatal factor and chlorophyll content under drought stress. In
addition, the contents of carotenoids and energy dissipation are
increased under drought stress. It indicates that carotenoids
play a role to dissipate excess energy of light reaction leading
to the decreased formation of active oxygen. Moreover, both the
contents of antioxidants (ascorbate and glutathione) and
activity of antioxidative enzymes (SOD, APX, MDHAR, DHAR, and
GR) are increased under drought stress leading to enhancing the
ability of scavenging active oxygen. The ability of the
photoprotection by carotenoids and antioxidant system is
enhanced under drought stress, so lipid peroxidation and ions
leakage are only slightly increased, and PSII photochemical
efficiency (Fv/Fm) was only slightly inhibited.Based on the
results shown above, papaya leaf is acclimated to the degree of
long-term drought stress used in this study, so it is resistant
to the oxygen stress induced by long-term drought stress.
URI: http://hdl.handle.net/11455/20661
Appears in Collections:生命科學系所

Show full item record
 

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.