| 外源一氧化氮供体SNP干旱条件对桑树幼苗光合作用和能量分配的影响 |
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| 引用本文： | 张婷,张会慧,许楠,孙广玉.外源一氧化氮供体SNP干旱条件对桑树幼苗光合作用和能量分配的影响[J].安徽农业科学,2013(22):9218-9222,9232. |
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| 作者姓名： | 张婷 张会慧 许楠 孙广玉 |
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| 作者单位： | 东北林业大学生命科学学院,黑龙江哈尔滨,150040;黑龙江省科学院自然生态与资源研究所,黑龙江哈尔滨,150040 |
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| 摘 要： | 目的]为探讨NO对桑树在干旱下光合作用的影响和光能分配的调控作用,研究了外源NO对干旱下桑树幼苗叶片的光合气体交换参数和叶绿素荧光参数的影响.方法]以一年生饲料桑为材料,以硝普钠（SNP）为NO供体,共设4个处理,每个处理3次重复.试验当天分别用Hoagland（CK）、1 mmol/L SNP＋ Hoagland（CK＋ SNP）、20％ PEG（6 000）＋ Hoagland（PEG）、20％PEG（6 000）＋1 mmol/L SNP＋ Hoagland（PEG＋ SNP）4种溶液对幼苗进行根施处理.结果]外施1 mmol/L SNP可有效提高干旱下桑树幼苗叶片最大净光合速率（Amax）,缓解净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、水分利用效率（WUE）的降低和胞间CO2浓度（Ci）的升高.干旱条件下桑树叶片的最大光化学效率（Fv/Fm）、电子传递速率（ETR）、光化学猝灭（qP）、实际光化学效率（（Φ）PSⅡ）均显著下降,初始荧光（Fo）和非光化学猝灭（NPQ）上升.根施SNP的干旱胁迫下桑树叶片的Pn、Gs、Tr、WUE、Fv/Fm、ETR、qP、（Φ）PSⅡ均明显提高,Fo和NPQ下降.根施SNP明显提高了桑树叶片的荧光量子产额和热耗散的量子产额（Φf,D）.20％ PEG（6 000）＋1 mmol/L SNP＋ Hoagland处理下用于光化学反应的量子产额（ΦPSⅡ）所占比例最高,依赖于类囊体膜两侧质子梯度和叶黄素循环的量子产额（ΦNPQ）所占比例较低.叶施SNP可以使桑树幼苗在严重干旱胁迫下用于QA-以后的电子传递能量比例增加,并且相对增大了有活性的反应中心的开放程度和电子传递速率,减轻了桑树幼苗在干旱胁迫下的光抑制.结论] NO能够缓解干旱胁迫引起的光合速率的下降及光抑制对光合系统的破坏作用,而非光化学效率的提高和热耗散的增强可能是NO减轻PSⅡ能量负荷,恢复失活的PSⅡ活性,保护光合系统并提高光合速率的重要机制之一.
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| 关 键 词： | 一氧化氮 桑树 干旱胁迫 光合作用 叶绿素荧光 |
Effect of Exogenous SNP, a Nitric Oxide Donor, on Photosynthesis and Allocation of Photosynthetic Excitation Energy in Leaves of Mulberry under Drought Stress |
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| Institution: | ZHANG Ting et al (College of Life Science, Northeast Forest University, Harbin,. Heilogjiang 150040) |
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| Abstract: | Objective ] To explore the effect of exogenous nitric oxide on photosynthesis and the allocation of photosynthetic excitation energy of mulberry under the drought stress, this study examined the changes of exogenous nitric oxide on the gas exchange parameters of photosynthe- sis and the chlorophyll fluorescence parameters in leaves of mulberry under the drought stress. Method] The study used one-year-old fodder mulberry as the experimental material, and used sodium nitroprusside （SNP） as the donor of NO. The experiment had four treatments and re- peats every treatment three times. There were four solutions, such as Hoagland （ CK）, 1 mmol/LSNP ＋ Hoagland （ CK ＋ SNP）, 20% PEG （ 6 000） ＋ Hoagland（PEG） and 20% PEG（6 000） ＋ 1 mmol/LSNP ＋ Hoagland（ PEG ＋.SNP） to treat the roots of the mulberry on the study day. Result] The increases of the intercellular CO2 concentration （Ci ） and the decreases of the maximum net photosynthetic rate （A max）, the photosynthetic rate （ P, ）, stomatal conductance（ G, ）, transpiration rate （ Tr ）, water use efficiency（WUE） were significantly alleviated under the drought stress by pretreatment SNP in the normal concentration of CO2. Under drought stress, maximum photochemical efficiency （Fv/Fm）, electron transport rate （ETR）, photochemical quenching（ qp ）, actual PSII efficiency（ Ops, ） were significantly decreased, but ini- tial fluorescence （ Fo ） and non-photochemical quenching（NPQ） were significantly increased. After pretreated with SNP, Pn, Gs, Tr, WUE, Fv/Fm, ETR, qp and Фpsn were evidently increased, while Fo and NPQ were significantly decreased. After pretreated with SNP, a combined flux of fluorescence and constitutive, light-independent thermal dissipation （ Фf,D ） in the leaves of mulberries were significantly increased. Un- der pretreated with 20% PEG（6 000） ＋ 1 mmol/L SNP ＋ Hoagland, a flux associated with photochemical electron flow in active PSII reaction centers （ФPS II ） was the highest in the proportion, and light-independent thermal dissipation in active PSIIs （ФNPQ） was low. The rate of the later electron transports energy or the QA - under the serious drought could be increased by SNP, and the openness of activity reaction cen- ter and the electron transport rate were also increased. Conclusion] NO could alleviate the decrease of photosynthetic rate and the damage of photoinhibition on photosynthetic system. And the increase of non-photochemical efficiency and antennae heat dissipation was probably the mechanism that NO protected photosynthetic system and improved photosynthetic ability under drought stress. |
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| Keywords: | Nitric oxide Mulberry Drought stress Photosynthesis Chlorophyll fluorescence |
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