,, 纪洪亭, 刘兵, 马吉锋, 肖浏骏, 汤亮, 曹卫星, 朱艳,南京农业大学国家信息农业工程技术中心/农业农村部农作物系统分析与决策重点实验室/江苏省信息农业高技术研究重点实验室/江苏省现代作物生产协同创新中心,南京 210095Effects of Jointing and Booting Low Temperature Treatments on Photosynthetic and Chlorophyll Fluorescence Characteristics in Wheat Leaf
LIU LeiLei,, JI HongTing, LIU Bing, MA JiFeng, XIAO LiuJun, TANG Liang, CAO WeiXing, ZHU Yan,National Engineering and Technology Center for Information Agriculture, Nanjing Agricultural University/Key Laboratory for Crop System Analysis and Decision Making, Ministry of Agriculture and Rural Affairs/Jiangsu Key Laboratory for Information Agriculture/Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing 210095通讯作者:
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责任编辑: 杨鑫浩
收稿日期:2018-06-6接受日期:2018-07-10网络出版日期:2018-12-01
| 基金资助: |
Received:2018-06-6Accepted:2018-07-10Online:2018-12-01
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刘蕾蕾, 纪洪亭, 刘兵, 马吉锋, 肖浏骏, 汤亮, 曹卫星, 朱艳. 拔节期和孕穗期低温处理对小麦叶片光合及叶绿素荧光特性的影响[J]. 中国农业科学, 2018, 51(23): 4434-4448 doi:10.3864/j.issn.0578-1752.2018.23.004
LIU LeiLei, JI HongTing, LIU Bing, MA JiFeng, XIAO LiuJun, TANG Liang, CAO WeiXing, ZHU Yan.
0 引言
【研究意义】近百年来,自然的气候波动和人类活动的加剧导致地球气候正经历一次以全球变暖为主要特征的显著变化。在全球变暖背景下,极端低温发生的频率、强度和持续时间也在不断加强[1,2,3]。低温频发加剧了小麦生产系统的不稳定性,降低了小麦产量和品质[4,5]。光合作用是植物最基本的生理现象,是干物质积累的唯一途径[6]。同时,光合作用又是对低温最为敏感的生理过程之一[7],低温不仅伤害光系统I和光系统II,还会影响到暗反应即卡尔文循环过程[8,9]。因此,在全球变暖背景下,研究低温对小麦叶片光合特性的影响,定量分析低温处理下叶片光合速率与荧光参数的关系,可为未来气候条件下小麦抗寒品种选育及减灾丰产高效栽培管理措施制定等提供理论依据。【前人研究进展】低温（非致死）条件下,光合作用由于酶反应受到限制而遭受抑制,使光合碳同化表现出对氧浓度变化不敏感,继而降低植物的光合作用速率[10]。SINGLE等[11]认为小麦拔节期-7℃—0℃的夜间低温将对小麦叶片和茎秆组织产生破坏,降低小麦的光合作用速率。MARCELLOS等[12]通过人工气候室降温试验（设0℃,-1℃和-2℃ 3个低温处理,每个处理持续2 h）发现,温度越低导致小麦的光合速率下降越明显,且孕穗期经过-2℃处理后的植株光合性能3 d后仍无法恢复。另外,MARCELLOS等[12]还得出,低温胁迫对低叶位叶片光合速率的影响明显大于高叶位叶片,低温处理后高叶位叶片出现水泡,尖端坏死,而低叶位叶片则出现皱缩甚至死亡。李卫民等[13]通过对拔节至灌浆期的小麦叶片进行光合测定表明,低温明显降低了小麦的气孔导度和光合速率,进而减少了同化物的累积。为研究小麦植株光合特性对低温冻害的响应规律,任德超等[14]在可移动田间智能低温霜箱内设置了-1℃、-3℃、-5℃、-7℃和-9℃ 5个温度梯度,对拔节前期和拔节后期的小麦进行4 h低温处理,研究结果表明,小麦叶片光合速率、胞间CO2浓度、蒸腾速率和气孔导度均随温度的降低呈下降趋势,且拔节前期-7℃和拔节后期-5℃处理的小麦叶片各光合性能指标均较对照显著下降。关雅楠等[15]研究认为,分蘖期（-10℃连续处理2 d）和拔节期（0℃连续处理3 d）低温处理下,不同基因型小麦品种叶绿素荧光参数的变化不同,半冬性品种烟农19最大光化学效率、光化学猝灭系数和非光化学猝灭系数显著高于春性品种扬麦18,表明低温胁迫下烟农19光合器官损伤程度轻,具有较高的光合活性和较强的自我保护机制。【本研究切入点】综合国内外文献报道,前人就低温胁迫对小麦叶片光合特性的影响机理进行了大量研究,但已有研究均是在冰箱或人工霜箱中进行,温度的设置大都基于恒定的白天/夜间处理温度,并没有考虑自然条件下的温度日变化规律;再者,已有研究大多仅考虑低温水平对小麦叶片光合及荧光特性的影响,较少研究低温持续时间及低温水平和持续时间的交互作用效应。在自然环境下,低温胁迫是温度日变化规律下低温水平和持续时间的综合效应。另外,已有研究大都是定性描述低温对小麦叶片光合作用和叶绿素荧光参数的影响,缺乏低温胁迫下小麦光合及荧光特性的定量研究。【拟解决的关键问题】本研究以温度敏感性不同的扬麦16和徐麦30为材料,在人工气候室中实施自然温度日变化模式下不同低温发生时期、低温水平、低温持续时间及其互作的小麦盆栽试验,研究低温处理对小麦叶片光合及叶绿素荧光特性的影响,以期为未来气候条件下小麦安全生产及适应性栽培措施的制定提供参考依据。1 材料与方法
1.1 试验设计
低温处理试验于2013—2015年连续2个小麦生长季,在江苏省如皋市国家信息农业工程技术中心试验基地（120.33°E, 32.23°N）的全自动人工气候室进行。供试小麦品种为扬麦16（春性品种）和徐麦30（半冬性品种）。设置拔节期（S1）和孕穗期（S2）2个低温处理时期,并根据1981—2010年我国冬小麦主产区拔节至孕穗阶段出现的极端温度情况（图1）,于每个处理时期设置了4个低温水平和3个低温持续时间,其中4个低温水平分别为T1（6℃/16℃/11℃,处理阶段的日最低温度/最高温度/平均温度,分别用Tmin/Tmax/Tavg表示,CK）、T2（较CK平均低4℃,即设计为2℃/12℃/7℃,Tmin/Tmax/Tavg）、T3（较CK平均低8℃,即设计为-2℃/8℃/3℃,Tmin/Tmax/Tavg）、T4（较CK平均低12℃,即设计为-6℃/4℃/-1℃,Tmin/Tmax/Tavg）;3个低温持续时间分别为2 d（D1）、4 d（D2）和6 d（D3）。图1
新窗口打开|下载原图ZIP|生成PPT图11981—2010年我国冬小麦主产区拔节至孕穗阶段极端最低温度、温度日较差及平均低温持续天数
Fig. 1The lowest minimum temperature, diurnal temperature and low temperature duration from jointing to booting averaged from 1981 to 2010 in the main winter wheat growth region of China
试验分别于2013年11月4日和2014年11月3日进行,当天于高30 cm、直径25 cm的塑料桶里播种,每桶在3叶期留苗10株。小麦播种前每桶施用基肥0.9 g N、0.5 g P2O5和0.9 g K2O,拔节前追施0.9 g N,其他管理措施（如灌溉、病虫害防治等）同当地高产栽培管理,以确保小麦生长不受水分和病、虫、草害等限制。低温处理前将小麦置于自然生长环境中,根据各小麦品种的生育进程,分别于拔节期（群体50%植株基部第一节间伸长至离地面2 cm）和孕穗期（群体50%旗叶叶片全部抽出叶鞘,旗叶叶鞘包着的幼穗明显膨大）选取长势一致的小麦移入人工气候室中进行低温处理。低温处理阶段,为减少气候室内各方位光温的差异,每天对内、外侧桶的位置进行互换。低温处理结束后,将小麦置于对照的人工气候室内使其在对照环境下恢复7 d,之后搬出气候室外恢复自然生长环境,直至成熟。
1.2 人工气候室概况
人工气候室采用高透光玻璃构成,每个气候室长×宽×高分别为3.4 m×3.2 m×2.8 m,内安装有温、湿度控制设备、补光和自动换气设备,以便控制人工气候室中的温度、空气湿度、光照和CO2浓度,使其与外界大气环境基本保持一致。人工气候室的温度控制范围在冬春季为-10℃—30℃,夏秋季为10℃—45℃,室内温度均匀性允差为±1℃,湿度控制范围为20%—95%RH,CO2浓度控制范围为350—2 000 μmol·mol-1。采用卤素灯进行补光,以确保气候室内小麦生长能够获得足够的光照强度,晴天中午和阴天中午,人工气候室内的光强分别为1 380 μmol·m-1·s-1和240 μmol·m-1·s-1。人工气候室内的昼夜温度变化采用外界环境中温度日变化曲线模式进行控制,从而使得人工气候室内的温度日变化能够尽量符合自然条件下的温度日变化规律（图2）。图2
新窗口打开|下载原图ZIP|生成PPT图2人工气候室内控制温度的实测值与外界环境温度动态（数据获取于2015年3月25日）
Fig. 2Dynamics of the temperature in environment-controlled phytotron and ambient during low temperature treatment (data were observed on 25th, March, 2015)
1.3 测定项目与方法
1.3.1 光合指标测定 低温处理期间,于每天上午9：00—12：00,在人工气候室内采用美国Li-COR公司生产的Li-6400 XT型便携式光合测定系统测定小麦顶部第一张全展叶的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）等光合指标,每个处理测定5张叶片。测试时选择红蓝光源叶室,设定光量子密度（PAR）1 100 μmol·m-2·s-1。低温处理结束后,将低温处理的小麦移到对照温度下（T1,CK）进行恢复,继续每天测定光合数据直至处理后7 d。1.3.2 荧光参数测定 采用德国Walz公司生产的PAM2500测定小麦顶部第一张全展叶片的荧光参数,每个处理测试5张叶片。低温处理期间,于每天凌晨3：00—4：00在人工气候室内测定初始荧光（Fo）、最大荧光（Fm）和暗处理下PSⅡ的最大光化学效率（Fv/Fm）。将叶片充分光适应后,于每天上午9：00—12：00,测定小麦顶部第一张全展叶片的光化学猝灭系数（qP）、非光化学猝灭系数（NPQ）和PSⅡ实际光化学效率（ФPSII）等。处理结束后,将低温处理的小麦移到对照温度下（T1,CK）进行恢复,继续每天测定荧光数据直至处理后7 d。
1.4 数据处理
采用Microsoft Excel 2016对2年的试验数据进行数据统计,运用SPSS 18.0 进行数据分析。2 结果
2.1 拔节期和孕穗期低温处理对小麦叶片光合特性的影响
2.1.1 低温处理对小麦叶片净光合速率的影响 由图3可知,拔节期同一低温处理水平下（T1除外）,2个小麦品种叶片净光合速率（Pn）随低温持续时间的延长呈先下降后升高的趋势,并且2个小麦品种叶片Pn在处理后1—3 d降至最低,其值（T2—T4）分别较对照（T1）下降48.6%、69.3%和75.3%（2个小麦品种的平均值）。拔节期低温处理结束后,2个小麦品种叶片Pn开始回升,且均能够在1—6 d内恢复到对照水平（T1）。而孕穗期同一低温处理水平下（T1除外）,2个小麦品种叶片Pn均随低温持续时间的延长呈下降趋势。其中,T2和T3处理的Pn能够恢复到T1水平,而T4处理结束后叶片Pn一直持续下降。图3
新窗口打开|下载原图ZIP|生成PPT图3拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片净光合速率（Pn）的影响
a-d和e-h：扬麦16和徐麦30拔节期（S1）低温处理;i-l和m-p：扬麦16和徐麦30孕穗期（S2）低温处理;误差线代表平均值的标准差。■D1处理后恢复期,□D2处理后恢复期,○D3处理后恢复期,●低温处理期间。下同
Fig. 3Effects of different low temperature levels and durations on net photosynthetic rate (Pn) of the first full-extended wheat leaf at jointing and booting stages
a-d and e-h: Low temperature treatments for Yangmai16 and Xumai30 at jointing (S1); i-l and m-p: Low temperature treatments for Yangmai16 and Xumai30 at booting (S2). Error bars represent standard deviation of mean. ■ recovery after D1,□ recovery after D2,○ recovery after D3, ● low temperature duration. The same as below
拔节期和孕穗期低温处理期间,扬麦16和徐麦30叶片Pn均随温度的下降而下降,且孕穗期低温水平对叶片Pn的影响大于拔节期。另外,拔节期低温处理水平对扬麦16的影响大于徐麦30,而孕穗期低温处理水平对叶片Pn的影响在品种间差异不大。拔节期和孕穗期低温处理期间,最低温度每降低1℃,扬麦16叶片Pn平均降低6.2%和6.4%,徐麦30叶片Pn平均降低4.9%和6.9%。此外,从2个小麦品种低温处理结束后叶片Pn的恢复能力来看,拔节期低温处理结束后,徐麦30叶片Pn用于恢复的时间要少于扬麦16,而孕穗期低温处理后,2个小麦品种叶片Pn的恢复时间相差不大。
2.1.2 低温处理对小麦叶片气孔导度的影响 由图4可以看出,拔节期低温处理期间,T2水平下,随低温持续时间的延长,2个小麦品种叶片气孔导度（Gs）呈升高趋势,而在T3和T4水平下,两个小麦品种叶片Gs呈先下降后上升的趋势。拔节期低温处理结束后,小麦叶片Gs均能够恢复到对照水平。而在孕穗期低温处理期间,T2、T3和T4水平下,随低温持续时间的延长,2个小麦品种叶片Gs均呈下降趋势。其中,T4水平处理1 d,扬麦16和徐麦30叶片Gs仅为T1处理的9.2%和3.3%,T4处理2—6 d,扬麦16和徐麦30叶片Gs仅为T1处理的8.2%—24.3%和1.1%—3.9%。孕穗期低温处理结束后,除T4处理外,其他低温水平下的小麦叶片Gs均能够恢复到对照水平。
图4
新窗口打开|下载原图ZIP|生成PPT图4拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片气孔导度（Gs）的影响
Fig. 4Effects of different low temperature levels and durations on stomatal conductance (Gs) of the first full-extended wheat leaf at jointing and booting stages
拔节期和孕穗期低温处理期间,扬麦16和徐麦30叶片Gs均随温度的下降呈下降趋势,且孕穗期低温处理水平对Gs的影响大于拔节期。此外,低温处理水平对徐麦30叶片Gs的影响大于扬麦16。拔节期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片的Gs平均降低3.8%和6.5%,而孕穗期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片的Gs平均降低5.7%和8.0%。
2.1.3 低温处理对小麦叶片蒸腾速率的影响 由图5可以看出,低温处理下2个小麦品种叶片蒸腾速率（Tr）与Gs规律基本一致。拔节期低温处理期间,Tr随低温持续时间的延长呈先下降后上升的趋势（T1除外）。而在孕穗期低温处理期间,随低温持续时间的延长,Tr基本上呈下降趋势。其中,T4处理1 d,扬麦16和徐麦30叶片Tr仅为T1的10.0%和5.7%,T4处理2—6 d,扬麦16和徐麦30叶片Tr仅为T1的5.2%—18.5%和2.5%—4.6%。此外,除孕穗期T4水平外,其他低温处理下小麦叶片Tr基本上均可恢复到对照水平。
图5
新窗口打开|下载原图ZIP|生成PPT图5拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片蒸腾速率（Tr）的影响
Fig. 5Effects of different low temperature levels and durations on transpiration rate (Tr) of the first full-extended wheat leaf at jointing and booting stages
拔节期和孕穗期低温处理期间,扬麦16和徐麦30叶片Tr均随温度的下降而下降,孕穗期低温处理对Tr的影响大于拔节期,并且低温处理水平对徐麦30叶片Tr的影响大于扬麦16。拔节期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片Tr分别降低6.0%和6.9%。而在孕穗期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片Tr分别降低6.2%和7.6%。
2.2 拔节期和孕穗期低温处理对小麦叶片荧光参数的影响
2.2.1 低温处理对小麦叶片最大光化学效率的影响 由图6可知,拔节期低温处理期间,除T1水平外,2个小麦品种叶片最大光化学效率（Fv/Fm）均随低温持续时间的延长呈先下降后升高的趋势。拔节期T2、T3和T4水平下,扬麦16叶片Fv/Fm在低温处理后4 d降到最低,其值分别较T1下降8.7%、10.6%和12.5%,随后缓慢恢复;而徐麦30叶片Fv/Fm在低温处理后2 d降到最低,其值分别较T1下降4.3%、4.0%和6.9%,随后迅速恢复,表明拔节期低温处理对扬麦16叶片Fv/Fm的影响大于徐麦30。孕穗期低温处理期间,T2和T3水平下,扬麦16和徐麦30叶片Fv/Fm随低温持续时间的延长,其下降趋势不显著;而在T4水平下,2个小麦品种叶片Fv/Fm随低温持续时间的延长而呈显著下降,低温持续时间每增加1 d,T4处理的扬麦16和徐麦30叶片Fv/Fm分别较T1下降2.7%和1.8%。图6
新窗口打开|下载原图ZIP|生成PPT图6拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片最大光化学效率（Fv/Fm）的影响
Fig. 6Effects of different low temperature levels and durations on maximum photochemical efficiency (Fv/Fm) of the first full- extended wheat leaf at jointing and booting stages
拔节期和孕穗期低温处理期间,2个小麦品种叶片Fv/Fm均随温度的降低呈下降趋势。拔节期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片Fv/Fm（D1—D3）分别较T1降低0.7%和0.2%、1.1%和0.2%、0.8%和0.5%。而孕穗期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片Fv/Fm（D1—D3）分别较T1降低0.5%和0.8%、0.4%和0.9%、1.2%和0.7%。由此可见,拔节期低温水平对扬麦16叶片Fv/Fm的影响大于徐麦30,而在孕穗期则是徐麦30叶片Fv/Fm的影响大于扬麦16（D3除外）。另外,除孕穗期T4低温处理水平下,其他低温处理的小麦叶片Fv/Fm值均可恢复到对照水平。
2.2.2 低温对处理小麦叶片PSⅡ实际光化学效率的影响 由图7可以看出,拔节期低温处理期间,2个小麦品种叶片PSⅡ实际光化学效率（ФPSII）随低温持续时间的延长呈先下降后上升的趋势（除T1外）,一般在2—5 d,叶片ФPSII降至最低（图7）。与T1相比,拔节期T2、T3和T4水平下,扬麦16和徐麦30叶片ФPSII的最低值分别下降55.6%和38.9%、64.3%和53.3%、73.3%和56.8%。孕穗期低温处理期间,T2水平下,扬麦16叶片ФPSII随低温持续时间的延长呈下降趋势,持续时间每增加1 d,叶片ФPSII降低2.6%,而在T3和T4水平下,扬麦16叶片ФPSII随低温持续时间的延长变化不大,其值分别在0.28—0.31和0.06—0.11。在T2和T3水平下,徐麦30叶片ФPSII随孕穗期低温持续时间的延长呈显著下降,持续时间每增加1 d,叶片ФPSII分别降低3.8%和4.2%,而T4温度水平下,徐麦30叶片ФPSII随持续时间的延长变化不大,其值在0.08—0.12。
图7
新窗口打开|下载原图ZIP|生成PPT图7拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片PSⅡ实际光化学效率（ФPSII）的影响
Fig. 7Effects of different low temperature levels and durations on PSⅡ actual photochemical efficiency (ФPSII) of the first full- extended wheat leaf at jointing and booting stages
拔节期和孕穗期低温处理期间,2个小麦品种叶片ФPSII随温度的降低呈下降趋势,且孕穗期低温对小麦叶片ФPSII的影响大于拔节期。在拔节期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片ФPSII（D1—D3）分别降低6.0%和3.5%、5.8%和5.8%、5.7%和6.1%。而在孕穗期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片ФPSII（D1—D3）分别降低6.3%和5.9%、5.9%和6.1%、5.8%和6.5%。此外,除孕穗期T4外,低温处理结束后,2个小麦品种叶片ФPSII均可恢复到对照水平。
2.2.3 低温处理对小麦叶片光化学猝灭系数的影响 由图8可以看出,拔节期和孕穗期低温处理期间,2个小麦品种叶片光化学猝灭系数（qP）随低温持续时间的延长呈先下降后升高趋势,并且随温度的降低呈下降趋势,孕穗期低温处理水平对小麦叶片qP的影响大于拔节期。在拔节期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片qP（D1—D3）分别降低4.7%和2.4%、4.0%和4.5%、4.0%和5.3%。而在孕穗期低温处理期间,最低温度每降低1℃,扬麦16和徐麦30叶片qP（D1—D3）分别降低5.7%和5.9%、5.1%和4.9%、4.4%和5.4%。此外,在小麦拔节期,低温持续2 d处理（D1）下,低温水平对扬麦16叶片qP的影响大于徐麦30,而低温持续4 d处理（D2）下,低温水平对扬麦16叶片qP的影响要小于徐麦30。在孕穗期,D1和D2处理下,低温水平对叶片qP的影响在2个小麦品种间差异不大,但在低温持续6 d处理（D3）下,低温水平对徐麦30叶片qP的影响要大于扬麦16。此外,除孕穗期T4处理外,其他处理的叶片qP在低温处理结束后1—3 d均可恢复到对照水平。
图8
新窗口打开|下载原图ZIP|生成PPT图8拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片光化学猝灭系数（qP）的影响2.2.4 低温处理对小麦叶片非光化学猝灭系数的影响
Fig. 8Effects of different low temperature levels and durations on photochemical quenching (qP) of the first full-extended wheat leaf at jointing and booting stages
由图9可知,低温持续时间对扬麦16和徐麦30叶片非光化学猝灭系数（NPQ）的影响不大,但2个小麦品种叶片NPQ随温度的降低呈较为显著的上升趋势。D1处理下,NPQ在2个处理时期间差异不大,而D2和D3处理下,孕穗期低温对2个小麦品种NPQ的影响要大于拔节期,表明孕穗期低温处理下,小麦叶片光合器官吸收的光能以热耗散形式消耗为主,从而在一定程度上缓解低温导致的光抑制（图9）。低温处理结束后,除孕穗期T4外,其他处理的叶片NPQ在1—3 d内均可恢复到对照水平。
图9
新窗口打开|下载原图ZIP|生成PPT图9拔节期和孕穗期不同低温水平和持续时间对小麦第一张全展叶片非光化学猝灭系数（NPQ）的影响2.3 拔节期和孕穗期低温处理下小麦叶片净光合速率与荧光参数的关系
Fig. 9Effects of different low temperature levels and durations on non-photochemical quenching (NPQ) of the first full-extended wheat leaf at jointing and booting stages
由图10可知,叶片相对净光合速率与相对荧光参数密切相关,相对Pn与相对Fv/Fm、ФPSII、qP间存在显著的正相关关系,而与相对NPQ呈显著的负相关关系。线性方程的斜率表明,相对Fv/Fm、ФPSII、qP每降低0.01个单位,叶片相对Pn分别降低5.2%、1.0%、1.1%,而相对NPQ每增加1个单位,相对Pn降低16.2%。分析净光合速率与荧光参数的关系以选择最优的荧光参数,有助于定量分析低温处理下叶片净光合速率的变化。从4个荧光参数与叶片净光合速率的相关关系来看,与Pn的关系较好的为ФPSII和qP,其次是Fv/Fm,而NPQ与Pn的相关关系较差。
图10
新窗口打开|下载原图ZIP|生成PPT图10拔节期和孕穗期低温处理期间小麦叶片相对净光合速率与各相对荧光参数间的关系
**表示达到0.01显著水平 **, significant at P<0.01
Fig. 10Relationships between relative net photosynthesis rate and chlorophyll fluorescence parameters of wheat under different low temperature treatments at jointing and booting stages
3 讨论
光合作用是对低温最敏感的生理过程之一[16],关于低温对小麦叶片光合作用影响的研究已有较多报道[17,18,19]。前人研究多针对低温水平对小麦叶片光合作用的影响[9, 20],或针对低温持续时间对叶片光合作用的影响[21],较少考虑低温水平和持续时间的综合调控效应。即使有少量的研究同时考虑了低温水平和持续时间的综合效应[22],其温度的设置也不符合自然温度日变化规律,大都基于恒定固定的白天/夜间温度。因此,本研究通过在人工气候室中实施自然温度日变化模式下不同低温发生时期、低温水平和低温持续时间的小麦盆栽试验,分析低温环境下小麦叶片光合和荧光参数对低温的响应规律,定量低温处理下净光合速率与各荧光参数间的关系,以期为全球气候变化背景下中国小麦安全生产适应性措施和缓解策略的制定提供数据支持和理论依据。本研究表明,低温显著降低小麦叶片净光合速率,这与前人的研究一致[16, 20]。在拔节期低温处理期间,同一低温持续时间下,小麦叶片Pn随温度的降低而下降。在同一低温水平下,扬麦16和徐麦30在处理后1—3 d降至最低值,之后开始回升。其原因可能是短时间的低温适应增加了叶片光合过程中主要酶含量、促使光合同工酶的表达以及增强细胞膜的稳定性[23],从而在一定程度上缓解了低温对叶片光合作用的影响。而在孕穗期低温处理期间,小麦叶片Pn随温度的降低和低温持续时间的延长呈下降趋势,其原因可能是孕穗期低温对小麦Pn的影响大于拔节期处理,短期低温适应无法缓解低温对净光合速率的影响。关雅楠等[15]通过研究低温胁迫下不同基因型小麦品种光合性能的影响结果表明,分蘖期和拔节期低温胁迫下半冬性品种烟农19 Pn、Gs、Fv/Fm、qP、NPQ均高于弱春性品种郑麦9023和春性品种扬麦18,表明烟农19具有较高的光合活性和较强的自我保护机制。本研究表明,在小麦拔节期和孕穗期下,低温水平和低温持续时间对扬麦16 Pn的影响大于徐麦30,而低温水平和持续时间对荧光参数的影响在品种间的表现与Pn并不一致。例如,在拔节期,低温水平对扬麦16 Fv/Fm的影响大于徐麦30,而在孕穗期,低温水平对扬麦16和徐麦30 Fv/Fm的影响差异不大。这可能与扬麦16是春性品种,较半冬性的徐麦30对拔节期低温更为敏感有关。而到了孕穗期,小麦抗低温能力迅速减弱[24],两个小麦品种对低温的抗性逐渐降低,所以导致低温对2个品种间Fv/Fm的影响差异不大。MARCELLOS[25]研究认为,轻度低温胁迫后,小麦在正常温度下生长3 d,叶片净光合速率便可恢复到正常水平,而重度低温胁迫后叶片净光合速率无法恢复。FULLER等[26]报道,孕穗期以后-5℃处理下,小麦旗叶损伤很小,但温度低于-5℃,小麦旗叶损伤严重。本研究表明,拔节期T4温度处理后,小麦叶片在正常温度生长1—6 d便可恢复到正常水平,而孕穗期T4处理后,小麦叶片净光合速率显著下降,处理结束后7 d仍无法恢复到正常水平,表明小麦叶片临界致死温度随生育期的变化而变化,-6℃/4℃可能是孕穗期小麦叶片临界致死温度。
牟会荣等[27]研究表明,与“表观性”的气体交换指标相比,叶绿素荧光参数更具有反映“内在性”的特点。低温胁迫下,叶片叶绿素荧光参数的变化与低温程度有关[28,29]。本研究表明,叶片Fv/Fm、ФPSII和qP随温度水平的降低呈下降趋势,而NPQ则随温度水平的降低而显著增加。低温处理后,除孕穗期T4处理外,其他处理的叶片Fv/Fm、ФPSII、qP和NPQ均可恢复到正常水平。这表明拔节期和孕穗期适度低温下产生的光抑制并没有导致PSⅡ反应中心的损伤,PSⅡ反应中心活性和开放程度的下降起到了光保护的作用,而孕穗期T4处理的叶片PSⅡ反应中心遭受到不可逆损伤。
有关定量分析叶片光合速率与荧光参数的关系研究已有报道,而多数的研究多采用Fv/Fm来定量分析低温对作物叶片光合速率的影响[30,31]。本研究表明,相对叶片净光合速率（Pn）与相对最大量子产量（Fv/Fm）、相对实际的量子产量（ФPSII）、相对光化学猝灭系数（qP）间均存在显著的正相关关系,而与相对非光化学猝灭系数（NPQ）呈显著的负相关关系。从4个荧光参数与叶片净光合速率的相关关系来看,Pn与ФPSII和qP的关系较好,其次是Fv/Fm,而NPQ与Pn的相关关系较差。这表明,低温处理下,基于ФPSII和qP两个指标来定量分析Pn的变化较其他2个指标更能反映低温对叶片光合速率的影响。
4 结论
拔节期低温处理期间,扬麦16和徐麦30叶片Pn、Gs、Tr和Fv/Fm均随低温持续时间的延长呈先降低后升高的趋势,而在孕穗期低温处理期间,Pn、Gs、Tr和Fv/Fm则随低温持续时间的延长呈下降趋势。同一低温持续时间下,小麦叶片Pn、Gs、Tr、Fv/Fm、ФPSⅡ和qP均随温度的下降呈降低的趋势,而NPQ则随温度的下降显著增加。低温处理结束后,除孕穗期T4处理外,其他低温处理后的小麦叶片Pn、Gs、Tr、Fv/Fm、ФPSII、qP和NPQ均可恢复到对照水平。此外,低温处理下,相对Pn与相对Fv/Fm、ФPSII、qP呈显著的正相关关系,而与相对NPQ呈显著的负相关关系,且Pn与ФPSII、qP的相关性要好于Fv/Fm和NPQ。表明低温主要通过降低叶片PSII的实际量子产量和光化学猝灭系数,引起小麦叶片光合速率下降,降低小麦干物质积累,最终导致产量下降。
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被引期刊影响因子
DOI:10.1029/2011GL047103URL [本文引用: 1]
Analyses of climate model simulations and observations reveal that extreme cold events are likely to persist across each land-continent even under 21st-century warming scenarios. The grid-based intensity, duration and frequency of cold extreme events are calculated annually through three indices: the coldest annual consecutive three-day average of daily maximum temperature, the annual maximum of consecutive frost days, and the total number of frost days. Nine global climate models forced with a moderate greenhouse-gas emissions scenario compares the indices over 2091-2100 versus 1991-2000. The credibility of model-simulated cold extremes is evaluated through both bias scores relative to reanalysis data in the past and multi-model agreement in the future. The number of times the value of each annual index in 2091-2100 exceeds the decadal average of the corresponding index in 1991-2000 is counted. The results indicate that intensity and duration of grid-based cold extremes, when viewed as a global total, will often be as severe as current typical conditions in many regions, but the corresponding frequency does not show this persistence. While the models agree on the projected persistence of cold extremes in terms of global counts, regionally, inter-model variability and disparity in model performance tends to dominate. Our findings suggest that, despite a general warming trend, regional preparedness for extreme cold events cannot be compromised even towards the end of the century.
DOI:10.2174/138920211794520178URLPMID:21886453 [本文引用: 1]
Plants respond with changes in their pattern of gene expression and protein products when exposed to low temperatures. Thus ability to adapt has an impact on the distribution and survival of the plant, and on crop yields. Many species of tropical or subtropical origin are injured or killed by non-freezing low temperatures, and exhibit various symptoms of chilling injury such as chlorosis, necrosis, or growth retardation. In contrast, chilling tolerant species are able to grow at such cold temperatures. Conventional breeding methods have met with limited success in improving the cold tolerance of important crop plants involving inter-specific or inter-generic hybridization. Recent studies involving full genome profiling/ sequencing, mutational and transgenic plant analyses, have provided a deep insight of the complex transcriptional mechanism that operates under cold stress. The alterations in expression of genes in response to cold temperatures are followed by increases in the levels of hundreds of metabolites, some of which are known to have protective effects against the damaging effects of cold stress. Various low temperature inducible genes have been isolated from plants. Most appear to be involved in tolerance to cold stress and the expression of some of them is regulated by C-repeat binding factor/ dehydration-responsive element binding (CBF/DREB1) transcription factors. Numerous physiological and molecular changes occur during cold acclimation which reveals that the cold resistance is more complex than perceived and involves more than one pathway. The findings summarized in this review have shown potential practical applications for breeding cold tolerance in crop and horticultural plants suitable to temperate geographical locations. <br/> <br/> <br/>
DOI:10.1002/joc.1301URL [本文引用: 1]
Climate model output is used to analyze the behavior of extreme cold-air outbreaks (CAOs) under recent and future climatic conditions. The study uses daily output from seven GCMs run under late-twentieth century and projected twenty-first century radiative conditions (SRES A1B greenhouse gas emission scenario). We define a CAO as an occurrence of two or more consecutive days during which the local mean daily surface air temperature is at least two standard deviations below the local wintertime mean temperature. In agreement with observations, the models generally simulate modern CAOs most frequently over western North America and Europe and least commonly over the Arctic. These favored regions for CAOs are located downstream from preferred locations of atmospheric blocking. Future projections indicate that CAOs - defined with respect to late-twentieth century climatic conditions - will decline in frequency by 50 to 100% in most of the Northern Hemisphere during the twenty-first century. Certain regions, however, show relatively small changes and others actually experience more CAOs in the future, due to atmospheric circulation changes and internal variability that counter the thermodynamic tendency from greenhouse forcing. These areas generally experience greater near-surface wind flow from the north or the continent during the twenty-first century and/or are especially prone to atmospheric blocking events. Simulated reductions in CAOs are smallest in western North America, the North Atlantic, and in southern regions of Europe and Asia. The Eurasian pattern is driven by a strong tendency for the models to produce sea-level pressure (SLP) increases in the vicinity of the Mediterranean Sea (intermodel mean of 3 hPa), causing greater advection of continental air from northern and central Asia, while the muted change over western North America is due to enhanced ridging along the west coast and the increased frequency of blocking events. The North Atlantic response is consistent with a slowdown of the thermohaline circulation, which either damps the warming regionally or results in a cooler mean climate in the vicinity of Greenland. Copyright 漏 2006 Royal Meteorological Society.
DOI:10.1111/j.1365-2486.2012.02724.xURLPMID:24501066 [本文引用: 1]
Extreme climate, especially temperature, can severely reduce wheat yield. As global warming has already begun to increase mean temperature and the occurrence of extreme temperatures, it has become urgent to accelerate the 5–20 year process of breeding for new wheat varieties, to adapt to future climate. We analyzed the patterns of frost and heat events across the Australian wheatbelt based on 50 years of historical records (1960–2009) for 2864 weather stations. Flowering dates of three contrasting-maturity wheat varieties were simulated for a wide range of sowing dates in 22 locations for ‘current’ climate (1960–2009) and eight future scenarios (high and low CO2 emission, dry and wet precipitation scenarios, in 2030 and 2050). The results highlighted the substantial spatial variability of frost and heat events across the Australian wheatbelt in current and future climates. As both ‘last frost’ and ‘first heat’ events would occur earlier in the season, the ‘target’ sowing and flowering windows (defined as risk less than 10% for frost (<0 °C) and less than 30% for heat (>35 °C) around flowering) would be shifted earlier by up to 2 and 1 month(s), respectively, in 2050. A short-season variety would require a shift in target sowing window 2-fold greater than long- and medium-season varieties by 2050 (8 vs. 4 days on average across locations and scenarios, respectively), but would suffer a lesser decrease in the length of the vegetative period (4 vs. 7 days). Overall, warmer winters would shorten the wheat season by up to 6 weeks, especially during preflowering. This faster crop cycle is associated with a reduced time for resource acquisition, and potential yield loss. As far as favourable rain and modern equipment would allow, early sowing and longer season varieties (i.e. in current climate) would be the best strategies to adapt to future climates.
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DOI:10.1016/j.sajb.2005.03.002URL [本文引用: 1]
Photosynthetic characteristics were compared between two field-grown spring wheat ( Triticum aestivum L.) cultivars, Ningmai 8 (NM8) and its half-father sibling Ningmai 9 (NM9), to investigate the differences in photosynthetic decline of flag leaves between these two cultivars with different senescent appearance after emergence through senescence. Maximum photosynthetic activities for these two cultivars were observed at around 10 days after emergence (DAE). Photosynthetic functionally, therefore, 10 DAE was taken to define the point at which leaf senescence was initiated. During the photosynthetic rapid decline occurring after 27 DAE, as compared with NM8, NM9 showed a significantly higher Chl content, a higher Chl a/ b ratio, light-saturated photosynthetic rate ( P Ca = 360) and light- and CO 2-saturated photosynthetic rate ( P max), carboxylation efficiency (CE), but a significantly lower dark respiration rate ( R D) and CO 2 compensation point ( C comp). Thylakoid membranes in NM9 also showed a slightly higher electron transport activity of PS II, but similar absorption spectra properties measured at room temperature as compared to NM8. The slower photosynthetic decline may contribute some to its higher grain yield in NM9. Due to the slower decrease of Chl, CE and P Ca = 360, and the lower R D in NM9, flag leaf senescence was delayed in comparison to the earlier senescent NM8. Compared with its half-father sibling NM8, NM9 had a later onset and a slower rate of flag leaf senescence, which may be partly responsible for its higher grain yield.
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DOI:10.3321/j.issn:0578-1752.2006.09.008URL [本文引用: 1]
Two winter wheat (Tritium aestivum L.) cultivars, Linmai No.2 (resistant) and Yangmai No.5 (susceptible), were grown hydroponically to investigate the effects of exogenous silicon (Si) on photosynthetic and physiological parameters of the seedlings grown under cold stress. Wheat seedlings grown in nutrient solutions were treated with 0, 0.1or 1.0 mmol / L Si, and then were subjected to freezing stress. The results showed that the photosynthesis and photosynthetic efficiency of the seedlings were significantly inhibited under freezing stress, but significantly enhanced by added Si. In comparison with the control, freezing stress induced a decline in net photosynthetic rate (Pn), stomatal conductance (Cs), transpiration rate (Tr), stomatal limitation value (Ls) and water utiliy efficiency (WUE) in seedlings. However, exogenous Si significantly increased the Pn, Cs and Tr. The transpiration rate was decreased under freezing stress and even lower in Si-supplied cold treatment than in Si-deprived one. The content of chlorophyll, the value of chl a/chl b and the content of soluble sugar were decreased under freezing stress. Exogenous Si decreased the content of soluble sugar significantly in both cultivars, whereas it did not significantly increase the contents of chlorophyll or the value of chl a/chl b.
DOI:10.3321/j.issn:0578-1752.2006.09.008URL [本文引用: 1]
Two winter wheat (Tritium aestivum L.) cultivars, Linmai No.2 (resistant) and Yangmai No.5 (susceptible), were grown hydroponically to investigate the effects of exogenous silicon (Si) on photosynthetic and physiological parameters of the seedlings grown under cold stress. Wheat seedlings grown in nutrient solutions were treated with 0, 0.1or 1.0 mmol / L Si, and then were subjected to freezing stress. The results showed that the photosynthesis and photosynthetic efficiency of the seedlings were significantly inhibited under freezing stress, but significantly enhanced by added Si. In comparison with the control, freezing stress induced a decline in net photosynthetic rate (Pn), stomatal conductance (Cs), transpiration rate (Tr), stomatal limitation value (Ls) and water utiliy efficiency (WUE) in seedlings. However, exogenous Si significantly increased the Pn, Cs and Tr. The transpiration rate was decreased under freezing stress and even lower in Si-supplied cold treatment than in Si-deprived one. The content of chlorophyll, the value of chl a/chl b and the content of soluble sugar were decreased under freezing stress. Exogenous Si decreased the content of soluble sugar significantly in both cultivars, whereas it did not significantly increase the contents of chlorophyll or the value of chl a/chl b.
DOI:10.3321/j.issn:1008-505X.2009.03.008URL [本文引用: 2]
采用溶液培养试验,以抗寒性不同的两个小麦品种：临麦2号（高抗）和扬麦158号（低抗）为材料,研究短期低温胁迫下,加硅处理（Si 1.0 mmol/L）对小麦叶片光合作用生理参数（净光合速率、气孔导度、蒸腾速率、细胞间隙CO2浓度和水分利用效率）及其主要酶RuBPCase和PEPCase的影响。结果表明,在短期低温胁迫下,加硅处理显著提高了小麦叶片的净光合速率、气孔导度和水分利用效率。短期低温胁迫下,两小麦品种叶片RuBPCase活性显著降低,低抗品种降低幅度更大;但加硅处理后,低抗品种RuBPCase活性显著比不加硅处理高,且与无低温处理的对照没有显著差异。硅对低抗品种扬麦158缓解低温胁迫的效果要明显高于高抗品种临麦2号。硅能显著提高低温胁迫下小麦净光合速率与硅提高小麦叶片RuBPCase活性密切相关。短期低温胁迫使小麦PEPCase活力升高,加硅处理可以抑制低抗品种中PEP羧化酶的升高,但PEPCase活力在低温胁迫条件下上升的机理有待于进一步研究。
DOI:10.3321/j.issn:1008-505X.2009.03.008URL [本文引用: 2]
采用溶液培养试验,以抗寒性不同的两个小麦品种：临麦2号（高抗）和扬麦158号（低抗）为材料,研究短期低温胁迫下,加硅处理（Si 1.0 mmol/L）对小麦叶片光合作用生理参数（净光合速率、气孔导度、蒸腾速率、细胞间隙CO2浓度和水分利用效率）及其主要酶RuBPCase和PEPCase的影响。结果表明,在短期低温胁迫下,加硅处理显著提高了小麦叶片的净光合速率、气孔导度和水分利用效率。短期低温胁迫下,两小麦品种叶片RuBPCase活性显著降低,低抗品种降低幅度更大;但加硅处理后,低抗品种RuBPCase活性显著比不加硅处理高,且与无低温处理的对照没有显著差异。硅对低抗品种扬麦158缓解低温胁迫的效果要明显高于高抗品种临麦2号。硅能显著提高低温胁迫下小麦净光合速率与硅提高小麦叶片RuBPCase活性密切相关。短期低温胁迫使小麦PEPCase活力升高,加硅处理可以抑制低抗品种中PEP羧化酶的升高,但PEPCase活力在低温胁迫条件下上升的机理有待于进一步研究。
DOI:10.1104/pp.93.3.1268URL [本文引用: 1]
Photosynthetic efficiency at limiting light levels fell by >50% in tomato cv. Floramerica, but not in spinach, immediately upon reducing the temperature to 4 C. This effect was initially fully reversible in tomato upon rewarming, but became increasingly inhibitory if low temperature exposure under high light intensity was prolonged for >1 h. Based on determinations of photosynthetic metabolites...
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Abstract Frost becomes a problem to wheat Triticum aestivum cultivation in Australia because of the demands placed by the climate at critical stages of growth: summers are too hot and dry for grain production, and it is late spring and early winter which provide the combination of temperature and moisture most suitable for growth, but these are times of the year when frost is potentially damaging. Comments are made on crop development and freezing injury; variations in frost resistance between cultivars and species; internal and external barriers to ice penetration of the plant; lethal temperatures, anthesis and grain formation; and the development of frost resistant cultivars. -P.J.Jarvis
DOI:10.1071/PP9840007URL [本文引用: 2]
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对田间环境不同水分处理光合速率、蒸腾速率、叶片水分利用率和气孔导度的分析表明，增加土壤含水量有助于缓解空气高温低湿对小麦光合作用的胁迫。气温对蒸腾的促进作用随土壤含水量提高而得到加强，湿度降低对蒸腾的促进作用随土壤含水量提高而得到抑制。随着土壤含水量的增加，叶片水分利用率向高温低湿方向移动，低温低湿对气孔导度的抑制效应愈加明显。综合比较这几个指标，使叶片既能保持最高光合速率又能维持较高叶片水分利用率的土壤含水量为0．22g／g。
URL [本文引用: 1]
对田间环境不同水分处理光合速率、蒸腾速率、叶片水分利用率和气孔导度的分析表明，增加土壤含水量有助于缓解空气高温低湿对小麦光合作用的胁迫。气温对蒸腾的促进作用随土壤含水量提高而得到加强，湿度降低对蒸腾的促进作用随土壤含水量提高而得到抑制。随着土壤含水量的增加，叶片水分利用率向高温低湿方向移动，低温低湿对气孔导度的抑制效应愈加明显。综合比较这几个指标，使叶片既能保持最高光合速率又能维持较高叶片水分利用率的土壤含水量为0．22g／g。
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为研究小麦在经受低温冻害后植株光合特性和产量性状变化规律,以‘周麦22’为研究对象,于拔节前期和拔节后期,分别设置-1℃、-3℃、-5℃、-7℃、-9℃5个温度梯度及对照(CK),低温处理4h后,测定小麦光合特性和叶绿素SPAD值,并在收获后测量小麦植株性状变化.本研究结果表明,于拔节前期和后期,随温度的降低,小麦光合速率A,胞间CO2浓度Ci,叶片蒸腾速率E和气孔导度和GH2o逐渐降低.但于拔节前期,-7℃处理较CK显著降低,且各低温梯度于7天后逐渐恢复正常.而于拔节后期,-5℃处理较CK显著降低,于各低温梯度于3天后逐渐恢复正常;在小麦拔节前期,温度低于-9℃时,SPAD值明显降低,而在拔节后期,温度低于-5℃时,SPAD开始显著降低;低温发生时间推迟,小蘖穗高降低,穗长缩短,粒数和千粒重则降低,而株高和单株成穗数增加.随温度的降低,小蘖穗高、株高降低和穗粒数显著降低.在发生低温冻害后,小麦生物产量和籽粒产量均显著降低.
URL [本文引用: 1]
为研究小麦在经受低温冻害后植株光合特性和产量性状变化规律,以‘周麦22’为研究对象,于拔节前期和拔节后期,分别设置-1℃、-3℃、-5℃、-7℃、-9℃5个温度梯度及对照(CK),低温处理4h后,测定小麦光合特性和叶绿素SPAD值,并在收获后测量小麦植株性状变化.本研究结果表明,于拔节前期和后期,随温度的降低,小麦光合速率A,胞间CO2浓度Ci,叶片蒸腾速率E和气孔导度和GH2o逐渐降低.但于拔节前期,-7℃处理较CK显著降低,且各低温梯度于7天后逐渐恢复正常.而于拔节后期,-5℃处理较CK显著降低,于各低温梯度于3天后逐渐恢复正常;在小麦拔节前期,温度低于-9℃时,SPAD值明显降低,而在拔节后期,温度低于-5℃时,SPAD开始显著降低;低温发生时间推迟,小蘖穗高降低,穗长缩短,粒数和千粒重则降低,而株高和单株成穗数增加.随温度的降低,小蘖穗高、株高降低和穗粒数显著降低.在发生低温冻害后,小麦生物产量和籽粒产量均显著降低.
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选用不同基因型小麦品种(春性品种扬麦18、弱春性品种郑麦9023、半冬性品种烟农19),研究了分蘖期和拔节期低温对叶片光合和叶绿素荧光特性的影响.结果表明:分蘖期-10℃低温处理后,烟农19的净光合速率(Pn)、气孔导度(gs)、PSⅡ最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(NPQ)和PSⅡ非循环光合电子传递速率(ETR)显著高于扬麦18和郑麦9023;郑麦9023的gs、Fv/Fm、qP和NPQ显著高于扬麦18,胞间CO2浓度(Ci)显著高于烟农19;扬麦18的Ci显著高于烟农19,初始荧光(Fo)显著高于郑麦9023和烟农19.拔节期0℃低温处理后,烟农19的Pn、gs、Fv/Fm和qP显著高于扬麦18和郑麦9023,NPQ和ETR显著高于扬麦18;郑麦9023的Pn、gs、Fv/Fm和qP显著高于扬麦18,Fo显著高于烟农19;扬麦18的Ci和Fo显著高于郑麦9023和烟农19.分蘖期和拔节期低温胁迫下,半冬性品种烟农19具有较高的光合活性和较强的自我保护机制,弱春性品种郑麦9023次之,春性品种扬麦18最低.
URL [本文引用: 2]
选用不同基因型小麦品种(春性品种扬麦18、弱春性品种郑麦9023、半冬性品种烟农19),研究了分蘖期和拔节期低温对叶片光合和叶绿素荧光特性的影响.结果表明:分蘖期-10℃低温处理后,烟农19的净光合速率(Pn)、气孔导度(gs)、PSⅡ最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(NPQ)和PSⅡ非循环光合电子传递速率(ETR)显著高于扬麦18和郑麦9023;郑麦9023的gs、Fv/Fm、qP和NPQ显著高于扬麦18,胞间CO2浓度(Ci)显著高于烟农19;扬麦18的Ci显著高于烟农19,初始荧光(Fo)显著高于郑麦9023和烟农19.拔节期0℃低温处理后,烟农19的Pn、gs、Fv/Fm和qP显著高于扬麦18和郑麦9023,NPQ和ETR显著高于扬麦18;郑麦9023的Pn、gs、Fv/Fm和qP显著高于扬麦18,Fo显著高于烟农19;扬麦18的Ci和Fo显著高于郑麦9023和烟农19.分蘖期和拔节期低温胁迫下,半冬性品种烟农19具有较高的光合活性和较强的自我保护机制,弱春性品种郑麦9023次之,春性品种扬麦18最低.
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DOI:10.1111/j.1399-3054.2006.00627.xURL [本文引用: 1]
Photosynthesis is a highly integrated and regulated process which is highly sensitive to any change in environmental conditions, because it needs to balance the light energy absorbed by the photosystems with the energy consumed by metabolic sinks of the plant. Low temperatures exacerbate an imbalance between the source of energy and the metabolic sink, thus requiring adjustments of photosynthesis to maintain the balance of energy flow. Photosynthesis itself functions as a sensor of this imbalance through the redox state of photosynthetic electron-transport components and regulates photophysical, photochemical and metabolic processes in the chloroplast. Recent progress has been made in understanding how plants sense the low temperature signal. It is clear that photosynthesis interacts with other processes during cold acclimation involving crosstalk between photosynthetic redox, cold acclimation and sugar-signalling pathways to regulate plant acclimation to low temperatures.
DOI:10.1007/BF02185436URL [本文引用: 1]
DOI:10.1111/1365-3040.ep11612087URL [本文引用: 1]
First page of article
DOI:10.2134/agronj14.0460URL [本文引用: 2]
DOI:10.1134/S0012496609040127URLPMID:19760879 [本文引用: 1]
During their life cycle, plants are, as a rule, repeatedly subjected to not only general but also local action of unfavorable temperatures, in particular, to root cooling. This results in some functional and structural changes and/or disturbances in not only root cells but also in the cells of aboveground organs, which were not cooled. It is known, for example, that root exposure to low (but not damaging) temperature could improve leaf cell cold tolerance [1, 2] and also induce rather rapid changes in the water regime [3 5] and the rate of photosynthesis [5, 6]. However, the role of the roots in the development of leaf cell cold tolerance is not completely clear. Earlier, we have demonstrated that the improvement of leaf cell cold tolerance under the influence of low temperature on the whole wheat seedlings was accompanied by changes in the parameters of chlorophyll fluorescence and the content of photosynthetic pigments in the leaves [7]. However, there is no data concerning changes in the photosynthetic apparatus (PSA) activity after local root cooling.
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DOI:10.1007/s11120-013-9874-6URLPMID:23801171 [本文引用: 1]
Most plants show considerable capacity to adjust their photosynthetic characteristics to their growth temperatures (temperature acclimation). The most typical case is a shift in the optimum temperature for photosynthesis, which can maximize the photosynthetic rate at the growth temperature. These plastic adjustments can allow plants to photosynthesize more efficiently at their new growth temperatures. In this review article, we summarize the basic differences in photosynthetic reactions in C 3 , C 4 , and CAM plants. We review the current understanding of the temperature responses of C 3 , C 4 , and CAM photosynthesis, and then discuss the underlying physiological and biochemical mechanisms for temperature acclimation of photosynthesis in each photosynthetic type. Finally, we use the published data to evaluate the extent of photosynthetic temperature acclimation in higher plants, and analyze which plant groups (i.e., photosynthetic types and functional types) have a greater inherent ability for photosynthetic acclimation to temperature than others, since there have been reported interspecific variations in this ability. We found that the inherent ability for temperature acclimation of photosynthesis was different: (1) among C 3 , C 4 , and CAM species; and (2) among functional types within C 3 plants. C 3 plants generally had a greater ability for temperature acclimation of photosynthesis across a broad temperature range, CAM plants acclimated day and night photosynthetic process differentially to temperature, and C 4 plants was adapted to warm environments. Moreover, within C 3 species, evergreen woody plants and perennial herbaceous plants showed greater temperature homeostasis of photosynthesis (i.e., the photosynthetic rate at high-growth temperature divided by that at low-growth temperature was close to 1.0) than deciduous woody plants and annual herbaceous plants, indicating that photosynthetic acclimation would be particularly important in perennial, long-lived species that would experience a rise in growing season temperatures over their lifespan. Interestingly, across growth temperatures, the extent of temperature homeostasis of photosynthesis was maintained irrespective of the extent of the change in the optimum temperature for photosynthesis ( T opt ), indicating that some plants achieve greater photosynthesis at the growth temperature by shifting T opt , whereas others can also achieve greater photosynthesis at the growth temperature by changing the shape of the photosynthesis鈥搕emperature curve without shifting T opt . It is considered that these differences in the inherent stability of temperature acclimation of photosynthesis would be reflected by differences in the limiting steps of photosynthetic rate.
DOI:10.1111/j.1439-037X.2008.00320.xURL [本文引用: 1]
During the jointing stage, the frost resistance of young ears (FRYE) was tested each day for the main stem, and also for the first, second and third tillers of the wheat cultivars Jinmai 47 and Jing 411. At the same time, the developmental progression of young ears (DPYE) of the same four shoots was also recorded each day. In the shoots of both cultivars, FRYE decreased as development advanced through the jointing stage. FRYE dropped off particularly sharply at the point when the anther connective tissue formation phase (ACFP) started. Shoots developing later, though with lower levels of soluble sugar, tended to suffer less from frost injury than those developing earlier. Frost resistance of 12 cultivars (six early- and six late-maturing) was evaluated at ACFP. The results indicate that only one cultivar (Xin 11) is frost resistant, with no significant differences appearing among the other 11 cultivars. The results suggest that DPYE is an important factor affecting FRYE. Evaluation of frost resistance of wheat cultivars should thus be performed at the same phase to obtain a true measure of frost resistance. The early ACFP phase is suggested as being the most appropriate one for frost resistance evaluation.
DOI:10.1071/AR9770557URL [本文引用: 1]
DOI:10.1016/j.eja.2007.01.001URL [本文引用: 1]
Wheat is occasionally exposed to freezing temperatures during ear emergence and can suffer severe frost damage. Few studies have attempted to understand the characteristics of freezing and frost damage to wheat during late development stages. It was clearly shown that wheat appears to have an inherent frost resistance to temperatures down to 615 °C but is extensively damaged below this temperature. Acclimation, whilst increasing the frost resistance of winter wheat in a vegetative state was incapable of increasing frost resistance of plants at ear emergence. It is proposed that the ability to upregulate frost resistance is lost once vernalisation requirement is fulfilled. Culms and ears of wheat were able to escape frost damage at temperatures below 615 °C by supercooling even to as low as 6115 °C and evidence collected by infrared thermography suggested that individual culms on a plant froze as independent units during freezing with little or no cross ice-nucleation strategies to protect wheat from frost damage in the field appear to revolve around avoiding ice nucleation.
DOI:10.3864/j.issn.0578-1752.2008.02.040URL [本文引用: 1]
Four winter wheat (Triticum aestivum L) varieties YangMai 158, YangMai 11, Nainong 9918 and Nainong 02Y393 were used to study the effect of shading between tillering and maturity on photosynthesis and chlorophyll fluorescence in flag leaves. Shading showed little impact on flag leaf SPAD value of shading-resistant variety Yangmai 158 and Nannong 02Y393 while decreased SPAD value of shading-sensitive variety Yangmai 11 and Nannong 9918 during the early grain filling stage. However, shading significantly increased leaf SPAD value at late grain filling stage for all varieties. Shading decreased flag leaf net photosynthetic rate (Pn), photosynthetic system II (PSII) actual photochemical efficiency ( PSII), photochemical quenching of chlorophyll fluorescence (qP) and dry matter accumulation, while increased leaf origianl fluorescence (Fo) and maximum photochemical efficiency (Fv/Fm). The low Pn of flag leaves was related to decrease in 桅PSII and qP, and thereafter, the dry matter accumulation in plant was decreased under shading between tillering and maturity in wheat.
DOI:10.3864/j.issn.0578-1752.2008.02.040URL [本文引用: 1]
Four winter wheat (Triticum aestivum L) varieties YangMai 158, YangMai 11, Nainong 9918 and Nainong 02Y393 were used to study the effect of shading between tillering and maturity on photosynthesis and chlorophyll fluorescence in flag leaves. Shading showed little impact on flag leaf SPAD value of shading-resistant variety Yangmai 158 and Nannong 02Y393 while decreased SPAD value of shading-sensitive variety Yangmai 11 and Nannong 9918 during the early grain filling stage. However, shading significantly increased leaf SPAD value at late grain filling stage for all varieties. Shading decreased flag leaf net photosynthetic rate (Pn), photosynthetic system II (PSII) actual photochemical efficiency ( PSII), photochemical quenching of chlorophyll fluorescence (qP) and dry matter accumulation, while increased leaf origianl fluorescence (Fo) and maximum photochemical efficiency (Fv/Fm). The low Pn of flag leaves was related to decrease in 桅PSII and qP, and thereafter, the dry matter accumulation in plant was decreased under shading between tillering and maturity in wheat.
DOI:10.1016/j.plaphy.2007.09.006URLPMID:17977737 [本文引用: 1]
The change of chlorophyll fluorescence parameters in froze leaves of 3 leaf-age seedlings were examined using two winter barley cultivars (Chumai 1 and Mo 103) differing in cold tolerance to investigate physiological response to low temperature as affected by cold acclimation (under 3/1 °C, day/night for 5 days before freezing treatment) and irradiation size (high irradiance: 380 ± 25 μmol m 612 s 611 and low irradiance: 60 ± 25 μmol m 612 s 611) during recovery. The results showed that non-lethal freezing shock (exposed to 618 °C for 18 h) did not obviously affect maximum quantum efficiency in photosystem II (PSII), but dramatically increased non-photochemical quenching and reduced effective quantum yield in PSII. Cold acclimation significantly improved stability of photosynthetic function of leaves after freezing stress through buffering excessive energy and alleviating photoinhibition during recovery, indicating it increased recovery ability of barley plants from freezing injury. High irradiance was quite harmful to the stability of PSII in barley plants during recovery from freezing injury. The electron transport rate of PSII varied with cold-acclimation, irradiance and genotype. Cold acclimation caused significant increase in electron transport rate of PSII for relatively tolerant cultivar Mo 103, but not for relatively sensitive cultivar Chumai 1. It can be concluded that some chlorophyll fluorescence parameters during recovery from freezing shock may be used as the indicators in identification and evaluation of cold tolerance in barley.
DOI:10.1016/j.envexpbot.2014.02.005URL [本文引用: 1]
Jatropha curcas is a promissory species for biodiesel production. Chilling and freezing stress are major environmental constraints for its establishment as a result of the injury provoked on leaf photosynthetic apparatus. This study is aimed at evaluating the impact of chilling (40h at 4°C) and freezing (2h at 611, 612 and 613°C) on maximum leaf photosynthesis (Amax), in relation to stomatal conductance (gs) and photochemical activity. Two similar experiments were conducted in pots outdoors; treatments were performed in climate chambers at the stage of four expanded leaves per plant, and then returned outdoors. Leaf gas exchange, water status and fluorescence variables were measured at 1 and 30 days after the end of the treatments (DAT). At 1 DAT, Amax and gs were reduced up to 75% and 100% in chilling and freezing treatments, respectively. However, the intercellular CO2 concentration (Ci) showed an inverse pattern, discarding a determinant role in Amax reductions. A lower efficiency electron use for photosynthesis was detected for plants subjected to chilling and freezing stress. The potential efficiency of PSII (Fv/Fm), chlorophyll content (Chl) and relative water content (RWC) were only affected by the lowest freezing treatments, while chilling and intermediate freezing plants showed an increase of the non photochemical quenching (NPQ). Leaf death occurred in the lowest freezing treatments, while several residual effects on Amax, gs and electron transport rate (ETR) were also observed at 30 DAT in the survival plants. This work sheds light on the determinant processes involved in the depletion of photosynthesis by chilling and freezing injuries, revealing that low temperatures have persistent and detrimental effects on J. curcas crop establishment.
[本文引用: 1]
DOI:10.1016/S0378-4290(00)00107-6URL [本文引用: 1]
The response of dry matter accumulation and leaf photosynthesis in maize ( Zea mays L.) to low temperature has been documented during early phases of development, but little is known about the low-temperature response of maize during later phases of development. Studies were conducted in 1999 at the Cambridge Research Station, Ontario, Canada, to quantify the effect of low night temperature during grain filling on leaf photosynthesis of short-season maize hybrids. Plants were grown in a hydroponic system in the field with plants in the low-night temperature treatments exposed to 4°C from late afternoon (17:00 h) to the next morning (9:00 h). Plants of three maize hybrids (i.e., an older hybrid, Pride 5, and two more recent hybrids, Pioneer 3902 and Cargill 1877) were exposed to one night or three consecutive nights of 4°C at weekly intervals from tasseling to 6 weeks after silking. Carbon exchange rate (CER) was measured at 10:00, 12:00, 14:00, and 16:00 h on the second leaf above that subtending the topmost ear. Dark-adapted chlorophyll fluorescence ( F v/ F m) was measured at 9:00 h at 6 weeks after silking. Leaf CER of control plants declined almost linearly from about 50 μmol m 612 s 611 at tasseling to about 20 μmol m 612 s 611 at 6 weeks after silking with the rate of decline in the older hybrid approximately two times greater than that in the two newer hybrids. No trend in the reduction in cold-stressed leaf CER relative to the field-grown control was apparent from tasseling to 6 weeks after silking. Reduction in CER was greater during the morning than during the afternoon after exposure to 4°C and the reduction in leaf CER increased from 19.4% after one night, to 25.8% after two nights, and 30.2% after three nights. Mean reduction in leaf CER after one night at 4°C differed significantly among the three hybrids and was 29.7% for Pride 5, 15.4% for Pioneer 3902, and 13.5% for Cargill 1877. The reduction in leaf CER due to low night temperature was associated with a reduction in leaf chlorophyll fluorescence. In conclusion, maize hybrids differ significantly in leaf CER response to cold night temperature during the grain-filling period.
