楊樹種間耐旱性差異的生理生化基礎(chǔ)研究(完整版)
【正文】 后第八天有明顯回升, 分別恢復(fù)至對照水平的88%(群眾楊)和78%(中東楊)，并且未導(dǎo)致落葉。干旱脅迫使群眾楊葉片脯氨酸水平增高40%，表明在干旱初始階段有較明顯的滲透調(diào)節(jié)發(fā)生。木質(zhì)部導(dǎo)入的ABA(10ml 200mM)能誘導(dǎo)I214楊葉片的多胺和乙烯生物合途徑發(fā)生類似于干旱脅迫下的變化和落葉。通過比較玉米素、激動(dòng)素和BA等不同種類細(xì)胞分裂素與ABA的相互作用，結(jié)果表明激動(dòng)素與植物內(nèi)源激素玉米素的作用相同，也能拮抗ABA對氣孔運(yùn)動(dòng)的影響，而BA的作用相反。 ，群眾楊氣孔對ABA反應(yīng)最敏感，I214楊次之，中東楊的敏感性最低。因此，新蛋白質(zhì)的誘導(dǎo)產(chǎn)生對于耐旱的群眾楊適應(yīng)干旱逆境以及與之相關(guān)的高溫逆境可能是很重要的。 var. italica。 (P. pyramidalis + Salix matsudana). The effects of water stress on growth, photosynthesis and water status were investigated, and stomatal, nonstomatal Page: 4limitation li limitation of CO2 assimilation of the four genotypes were analyzed. The influence of water stress and external ABA application on polyamine, ethylene biosynthesis and their relationship with leaf abscission were examined. Genotypespecific differences in mechanisms of rootshoot munication of poplar in response to drought were elucidated for the first time, and the concept of a pound rootoriginated signal of ABA/cytokinins was put forward and preliminarily conformed. Furthermore, the difference between droughtsensitive and droughttolerant genotypes in stressresponsive polypeptides were pared and it was considered as molecular mechanisms involved in drought tolerance. The main results of the paper are detailed as follows:1. Under optimal moisture of 90%FFC (full field capacity, soil water potential ), net photosynthetic rate (Pn) of four experimented genotypes were limited by air drought. Comparatively, Berolinensis was the most tolerant to air drought because its stomata were insensitive to low air humidity, allowing to keep a relatively high stomatal conductance for gas exchange(Pn, TRN) and water use efficiency.2. Under high soil moisture of 70～100%FFC (soil water potential ～), Italica kept the highest Pn and growth rate and Robusta was next. However, Italica and Robusta were very responsive to soil drought and significant reductions of Pn appeared when soil moisture was lowered to 40% FFC. After subjected to severe soil drought (30% FFC, soil water potential ), Pn was dramatically suppressed and about one quarter to one third of the leaves of droughted plants for the two genotypes were shed, and growth of expanding leaves was decreased by 51% (Italica) and 37% (Robusta), respectively. And stem height growth of Italica was almost halted, whereas only a moderate effect on leaf growth was found, there was no leaf abscission at all for Berolinensis and Popularis. Although the severe soil drought significantly decreased Pn of Berolinensis and Popularis as well in the first several days, an obvious recovery of Pn displayed in the 8th day of exposure to water shortage. In conclusion, Popularis kept the highest productivity under soil moisture of 30%FFC among the four poplar genotypes and Italica was the lowest.3. The effects of water stress on photosynthesis and chlorophyll a (Chl a ) fluorescence were investigated in
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