Caragana korshinskii seedlings maintain positive photosynthesis during short-term, severe drought stress
Caragana korshinskii seedlings maintain positive photosynthesis during short-term, severe drought stress
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柠条幼苗在短期严重干旱胁迫下保持积极的光合作用
DOI：
10.1007/s11099-011-0067-2
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发表时间：
2011-12-01
期刊：
影响因子：
2.7
通讯作者：
Guo, X. S.
中科院分区：
文献类型：
--
作者：
Fang, X. W.;Turner, N. C.;Guo, X. S.
幼苗的表现可以决定植物的分布，特别是在水分有限的环境中。柠条（Caragana korshinskii）是我国西北干旱、半干旱地区常见的植物，其对水分胁迫的耐受方式多种多样，但其在生长初期水分胁迫下的表现尚不清楚。在1：1的黄土和珍珠岩混合土中，对1年生的幼苗在（1）水分亏缺20 d和（2）充分供水条件下的水分关系、光合活性、叶绿素（Chl）含量和脯氨酸积累进行了测定。水分亏缺导致黎明前叶水势（LWP）降低（-6.1MPa），但不引起任何叶片脱落。水分亏缺后，叶片气孔导度（g（s））、蒸腾速率（E）和净光合速率（P（N））立即下降，而光系统II（PSII）的最大光化学效率（F-v/F-m）和PSII的有效量子效率（I破垂直条（PSII））在15 d后下降。g（s）的早期快速下降、E的减少、Chl（a+B）损失的增加、PSII的表观电子光化学传递速率（ETR）/P（N）的增加以及非光化学荧光猝灭（NPQ）和脯氨酸的逐渐增加可能是防止I-断裂垂直栅（PSII）光损伤的原因。C. korshinskii幼苗采用了一种耐胁迫的策略，考虑到生长季节偶尔的降雨事件，保持叶片提供了明显的选择优势。
Seedling performance may determine plant distribution, especially in water-limited environments. Plants of Caragana korshinskii commonly grow in arid and semiarid areas in northwestern China, and endure water shortage in various ways, but little is known about their performance when water shortage occurs at early growth stages. The water relations, photosynthetic activity, chlorophyll (Chl) content and proline accumulation were determined in 1-year-old seedlings growing in a 1:1 mixture of Loess soil and Perlite and subjected to (1) a water deficit for 20 days and (2) kept adequately watered throughout. The water deficit induced low (-6.1 MPa) predawn leaf water potentials (LWP), but did not induce any leaf abscission. Stomatal conductance (g (s)), leaf transpiration rate (E), and net photosynthetic rate (P (N)) decreased immediately following the imposition of the water deficit, while the maximal photochemical efficiency of photosystem II (PSII) (F-v/F-m) and the effective quantum yield of PSII (I broken vertical bar(PSII)) decreased 15 days later. An early and rapid decrease in g (s), reduced E, increased Chl (a+b) loss, increased the apparent rate of photochemical transport of electrons through PSII (ETR)/P (N), as well as a gradual increase in non-photochemical quenching of fluorescence (NPQ) and proline may have contributed to preventing I broken vertical bar(PSII) from photodamage. C. korshinskii seedlings used a stress-tolerance strategy, with leaf maintenance providing a clear selective advantage, considering the occasional rainfall events during the growing season.