,1,*, 宁堂原,1,*Increasing phosphate fertilizer application to improve photosynthetic capacity and yield of summer soybean in weak light environment
ZHAO Wei1,**, ZHEN Tian-Yue1,**, ZHANG Zi-Shan2, XU Zheng1, GAO Da-Peng1, DING Cong1, LIU Peng1, LI Geng,1,*, NING Tang-Yuan,1,*通讯作者:
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收稿日期:2019-05-22接受日期:2019-08-9网络出版日期:2019-09-11
| 基金资助: |
Received:2019-05-22Accepted:2019-08-9Online:2019-09-11
| Fund supported: |
作者简介 About authors
赵伟,E-mail:15621579298@163.com。
甄天悦,E-mail:13563691279@163.com。
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赵伟, 甄天悦, 张子山, 徐铮, 高大鹏, 丁聪, 刘鹏, 李耕, 宁堂原. 增施磷肥提高弱光环境中夏大豆叶片光合能力及产量[J]. 作物学报, 2020, 46(2): 249-258. doi:10.3724/SP.J.1006.2020.94078
ZHAO Wei, ZHEN Tian-Yue, ZHANG Zi-Shan, XU Zheng, GAO Da-Peng, DING Cong, LIU Peng, LI Geng, NING Tang-Yuan.
大豆原产我国, 是重要的粮油作物之一, 在国民经济和人民生活中占有重要地位。影响大豆生产规模的因素较多, 其中单产较低是最为突出的因素之一。除土壤、肥料之外, 光照是植物生长发育不可或缺的环境因子之一, 是光合作用的主要能量来源, 也是植物生长和发育的一个重要信号[1,2]。近50年来, 由于人类活动引起的气溶胶浓度增加及其伴生的轻雾、低云导致作物的受光量和日照时数呈下降趋势, 以黄淮海区为例, 阴雨寡照在夏大豆生长期(6月至10月)内时有发生[3], 是限制大豆产量的重要因素之一。
弱光会改变植物的根、茎及叶片的形态结构, 导致多种生物代谢途径性能下降, 影响植物生长发育和干物质积累效率, 其中叶片的光合作用是对弱光响应最敏感的代谢过程[4,5]。前人研究表明, 弱光环境中大豆通过增加叶面积、叶绿素含量及光系统内天线色素蛋白提高光照截获量和光能的吸收效率[6], 但无法改变光能转化与电子传递效率降低的趋势[7], 导致光系统性能明显下降[8], 此外, 叶片光合碳固定酶系表达量与活性亦呈现明显下降趋势[9,10,11], 因此, 弱光下光合作用能力降低是一种必然的结果。进一步研究表明, 弱光下叶片光合能力的大幅下降可以通过合理的栽培措施[12]与充足的水[13]、肥[14]调控而减轻, 缓解光合能力与产量的下降。增加营养元素是作物提高弱光利用的重要方式之一[15], 大豆是需磷量较大的作物, 整个生育期对磷的反应敏感, 磷肥的合理施用是调控大豆生长发育与产量形成的重要措施[16]。其机理普遍认为是磷素具有调节类囊体膜稳定性及贯穿于膜内外的光合蛋白活性的作用, 从而影响光合电子传递、光合磷酸化、卡尔文循环、同化物合成及转运效率, 进而调节作物光合作用[17,18]。
前人研究针对环境光强或磷素作为单一因素提高作物叶片光合能力与增加产量的生理机理多有报道[19,20], 大田试验结果明确表明, 磷素的施用量与叶片光合速率之间存在有限的线性关系, 当施磷量超过一定比例之后, 光合作用强度不再增加[21], 这说明, 光照与磷素的资源属性虽不一致, 但二者之间存在一定的互补效应。弱光环境下, 磷素的施用与否及施用多少与作物利用弱光效率高低的相关性研究较少, 其互补的机制尚不明确, 磷肥补偿光强降低, 相对提高光合作用强度的效果仍需进一步明确。对此, 本试验探究了不同光照环境下, 磷素与光强之间的互补效应变化趋势, 以及磷肥施用量与弱光利用效率之间的关系与机制, 以期创新作物高效利用弱光的农艺生产模式, 为黄淮海夏大豆弱光高效利用及磷肥合理施用提供理论依据。
1 材料与方法
1.1 试验设计
2017年和2018年在山东农业大学水肥耦合研究试验站栽培池(长×宽×深为5.0 m×3.6 m×2.4 m)内种植齐黄34, 每穴2株, 种植密度为12万株 hm-2, 重复3次。设置2个光照水平, 即以田间自然光强作为对照(L1)和由始花期前5 d开始直至收获结束利用遮阳网形成透光率(60±5)%的弱光环境(L2)。设置3个磷肥水平, P2O5 (过磷酸钙)施用量分别为0 kg hm-2 (P0)、120 kg hm-2 (P1)、180 kg hm-2 (P2)。施用尿素(纯氮≥46.3%) 300 kg hm-2、硫酸钾(K2O ≥ 50%) 300 kg hm-2。磷肥与钾肥于播种期一次性基施, 氮肥于播种期和结荚初期各施50%。整个生育期内保证水分供应, 及时防治病虫草害。1.2 测定项目及方法
1.2.1 产量和产量构成因素 成熟期连续取10株大豆, 每处理重复3次, 室内考种测定产量构成因素数据, 而后脱粒并晒干至籽粒含水量约为13.5%时, 测定籽粒产量。1.2.2 叶面积 于始花期(R1)、结荚初期(R3)、鼓粒初期(R5)、成熟初期(R7)选取长势一致的3株大豆, 使用LI-3100C台式叶面积仪(Li-Cor, 美国)扫描单株叶片叶面积, 扫描后的叶片于105℃杀青30 min, 80℃烘干至恒重后称重。
比叶面积(SLA, cm2 g-1) = 叶面积(cm2)/叶干重(g)
1.2.3 光合色素 参照Lichtenthaler [22]的方法(略有改动), 将叶片切成长约5 mm, 宽约2 mm的细丝, 用80%丙酮溶液浸提48 h。使用UV-2450紫外可见分光光度计(日本岛津公司)将浸提液分别在663 nm (A663)、646 nm (A646)波长下比色, 所得光密度值代入公式计算溶液叶绿素a (Chl a)和叶绿素b (Chl b)含量。
Chl a (μg mL-1) = 12.21A663-2.81A646
Chl b (μg mL-1) = 20.13A646-5.03A663
1.2.4 光合有效辐射 将PAR Light Sensor光量子传感器(Spectrum, 美国)固定于大豆功能叶上方, 于晴天8:00-18:00测定光照强度, 设置每处理5部传感器, 取平均值。通过Watch dog (Spectrum, 美国)采集器收集数据, 设定记录频率为1 time min-1。
1.2.5 光合气体交换参数 使用CIRAS-II (PP System, 美国)于晴天测定大豆功能叶(主茎倒四叶)净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)等气体交换参数, 通过电脑编程设定光合仪各参数人工光源光质为90%红光+10%蓝光, 光强为1400 μmol m-2 s-1, CO2浓度为380 μmol m-2 s-1, 叶室相对湿度与温度分别为60%与30℃, 根据测定数据重复性每处理重复5~10次不等。
1.2.6 快速叶绿素荧光诱导动力学曲线(OJIP)
参考Alaka等[24]的方法, 测定前先将叶片暗适应30 min, 使用Handy PEA (Hansatech, 英国)测定叶片快速叶绿素荧光诱导动力学曲线(OJIP曲线)。根据Strasser等[25]的方法, 分析OJIP 荧光诱导曲线。分析时需知Fo (20 μs时荧光, O相)、Fk (300 μs时的荧光, K相)、Fj (2 ms时的荧光, J相)、Fi (30 ms时的荧光, I相)、Fm(最大荧光, P相); 可变荧光Fk占Fj-Fo振幅的比例Wk = (Fk-Fo)/(Fj-Fo); 可变荧光Fj占Fm-Fo振幅的比例Vj=(Fj-Fo)/(Fm-Fo); PSII最大光化学效率φPo = [1-(Fo/Fm)]; 吸收的光能用于电子传递的效率φEo = [1-(Fo/Fm)]·(1-Vj)。
1.3 数据处理与统计分析
产量相关指标、单株叶面积、比叶面积、叶绿素含量、叶片气体交换参数分别使用2017年和2018年2年数据; 光合有效辐射与光系统II (PSII)相关指标使用2018年1年数据。使用SigmaPlot 10.0软件作图, Microsoft Excel 2016处理数据, 应用 SPSS16.0 统计分析软件进行试验数据的方差分析、显著性分析(LSD法)及数据差异显著性检验。2 结果与分析
2.1 产量和产量构成因素
由表1可知, 相同光照条件下, 大豆产量随施磷量提高呈显著增加趋势。自然光照环境下, 大豆产量显著高于弱光环境下, 且表现为L1P2>L1P1> L1P0>L2P2>L2P1>L2P0。不同光强环境下, 磷肥施用量对大豆产量的影响不同。自然光强(L1)下, 正常施磷(P1)与增施磷肥(P2)较不施磷肥(P0) 2年平均产量分别提高5.15%和3.15%; 弱光条件(L2)下, P1与P2较P0处理2年平均增产8.45%与12.25%。可见, 弱光环境下, 大豆产量随磷肥施用量的增加而显著提高, 其增幅明显高于自然光照条件下。自然光照下, 磷肥以促进大豆单株有效荚数增加产量; 弱光下, 磷肥在提高单株有效结荚数基础上, 同步提高单株粒数, 是其增产幅度高于自然光照下的主要原因。Table 1
表1
表1不同施磷量和遮光处理对夏大豆产量及产量构成因素的影响
Table 1
| 年份 Year | 处理Treatment | 百粒重 100-seed weight (g) | 单株有效荚数 Effective pods per plant | 单株粒数 Seeds per plant | 产量 Yield (kg hm-2) | |
|---|---|---|---|---|---|---|
| 光照 Light | 磷肥 Phosphorous | |||||
| 2017 | L1 | P0 | 28.08 c | 50.00 c | 116.30 b | 3918.28 c |
| P1 | 28.26 c | 54.70 b | 120.73 a | 4094.59 b | ||
| P2 | 28.42 bc | 59.80 a | 124.06 a | 4231.07 a | ||
| L2 | P0 | 29.41 ab | 29.60 f | 66.09 e | 2332.27 f | |
| P1 | 29.81 a | 35.00 e | 71.16 d | 2545.21 e | ||
| P2 | 30.03 a | 39.10 d | 78.12 c | 2815.48 d | ||
| 变异来源 Source of variation | 方差分析 Analysis of variance | |||||
| 光照 Light (L) | ** | ** | ** | ** | ||
| 磷肥 Phosphorous (P) | NS | ** | ** | ** | ||
| 光照×氮肥 (L×P) | NS | NS | * | * | ||
| 2018 | L1 | P0 | 28.16 a | 51.88 b | 118.03 b | 3988.97 c |
| P1 | 28.48 a | 52.25 b | 123.45 a | 4218.65 b | ||
| P2 | 28.62 a | 54.11 a | 126.48 a | 4344.13 a | ||
| L2 | P0 | 29.00 a | 31.75 d | 66.65 e | 2319.62 f | |
| P1 | 29.07 a | 35.64 c | 71.70 d | 2500.61 e | ||
| P2 | 29.21 a | 34.48 c | 81.25 c | 2847.66 d | ||
| 变异来源 Source of variation | 方差分析 Analysis of variance | |||||
| 光照 Light (L) | NS | ** | ** | ** | ||
| 磷肥 Phosphorous (P) | NS | ** | ** | ** | ||
| 光照×氮肥 (L×P) | NS | * | * | * | ||
新窗口打开|下载CSV
2.2 光合有效辐射
由于太阳光照角度的日变化, 遮阴后光照有效辐射为自然光照的55%~65%。由图1可知, 自然照光处理(L1)全天有7~9 h处于高光强(>1000 μmol m-2 s-1)环境, 而遮阴处理(L2)仅中午3~4 h接受较高光合有效辐射。图1
新窗口打开|下载原图ZIP|生成PPT图1遮阴后对大豆冠层光合有效辐射量的影响
L1: 自然光强; L2: 透光率(60±5)%的弱光环境。
Fig. 1Effects of shade on photosynthetic active radiation of soybean canopy
L1: natural light environment; L2: low light environment with light transmittance of (60±5)%.
2.3 单株叶面积与比叶面积
与自然光照(L1)处理相比, 大豆开花前期开始遮阴所形成的弱光环境对大豆的叶面积(图2-A)与比叶面积(图2-B)的影响自结荚初期(R3)始呈明显差异。相同施磷量条件下, 弱光环境中大豆叶面积(LA)与比叶面积(SLA)均显著高于自然光照环境中。相同光照环境条件下, 施用磷肥(P1)与增施磷肥(P2)处理与不施磷肥(P0)相比, 其结荚-鼓粒初期(R3-R5)的LA均呈显著增加趋势, 而SLA则随施磷量的增加而呈显著降低趋势。分析各处理的LA与SLA的变化幅度发现, 与磷肥因素相比, 光照强度对大豆花后LA与SLA的影响更加明显。图2
新窗口打开|下载原图ZIP|生成PPT图2不同施磷量和遮光处理对花后大豆叶面积的影响
不同字母表示处理间差异在0.05水平差异显著。R1: 始花期; R3: 结荚初期; R5: 鼓粒初期; R7: 成熟初期; LA: 单株叶面积; SLA: 比叶面积。处理同
Fig. 2Effects of different phosphate fertilizer application and light environment treatments on soybean leaf area after anthesis
Different letters indicate significant differences among treatments at the 0.05 probability level. R1: beginning flowering; R3: beginning pod; R5: beginning seed; R7: beginning maturity; LA: leaf area per plant; SLA: specific leaf area. Treatments are the same as those given in
2.4 叶绿素含量变化
花后相同生育期的Chl a与Chl b含量随光照强度降低和施磷量增加而升高(图3)。与施磷量和光照强度变化对叶面积的影响相同, 弱光环境(L2)是大豆花后叶绿素含量显著提高的首要原因。不同的光照环境, 磷肥施用量对叶绿素含量的提高作用亦存在明显的差异, 在自然光照(L1)环境下, 与不施磷肥(P0)相比, 正常施磷(P1)与增施磷肥(P2)结荚初期(R3)叶片的Chl a分别增加11.7%与21.6%, 显著小于弱光环境中相同磷肥处理的19.8%与30.7%增幅。Chl b及鼓粒初期(R5)同类数值的变幅一致。可见, 弱光环境下增施磷肥对于叶片叶绿素含量的提高较自然光照环境作用更加显著。图3
新窗口打开|下载原图ZIP|生成PPT图3不同施磷量和遮光处理对花后大豆叶片叶绿素含量的影响
不同字母表示处理间差异在0.05水平差异显著。R1: 始花期; R3: 结荚初期; R5: 鼓粒初期。处理同
Fig. 3Effects of different phosphate fertilizer application and light environment treatments on chlorophyll content of soybean leaf after anthesis
Different letters indicate significant differences among treatments at the 0.05 probability level. R1: beginning of flowering; R3: beginning of podding; R5: beginning of grain filling. Treatments are the same as those given in
2.5 叶片气体交换参数
2年气体交换参数均表明(图4), 相同施磷量下, 弱光环境显著降低大豆结荚-鼓粒期(R3-R5)叶片的净光合速率(Pn, 图4-A, B)与气孔导度(Gs, 图4-C, D), 提高胞间CO2浓度(Ci, 图4-E, F), 说明弱光环境下大豆花后叶片Pn降低的原因是非气孔因素导致。不同光照强度下, 花后R3~R7时期叶片的Pn均随施磷量增加而上升, 但其增幅并不一致。R3时期, 自然光照(L1)环境下正常施磷(P1)与增施磷肥(P2)处理的Pn, 较不施磷(P0)处理2年平均提高10.2%与22.1%, 弱光环境下P1与P2处理的Pn较P0处理则增加16.2%与32.7%, 虽然弱光环境下P1与P2处理的叶片Pn绝对值小于自然光照环境下, 但其相对增幅却显著提高, 而且弱光环境下Pn提高的幅度随着施磷量的增幅明显大于自然光照下, 这表明增施磷肥对于缓解弱光条件下大豆叶片Pn的降低具有明显的作用。R5与R7两个生育时期亦呈现相同的规律。图4
新窗口打开|下载原图ZIP|生成PPT图4不同施磷量和遮光处理对花后大豆叶片气体交换参数的影响
不同字母表示处理间差异在0.05水平差异显著。R1: 始花期; R3: 结荚初期; R5: 鼓粒初期; R7: 成熟初期。处理同
Fig. 4Effects of different phosphate fertilizer application and light environment treatments on gas exchange parameters of soybean leaf after anthesis
Different letters indicate significant differences among treatments at the 0.05 probability level. R1: beginning of flowering; R3: beginning of podding; R5: beginning of grain filling; R7: beginning of maturity. Treatments are the same as those given in
2.6 不同处理对大豆叶片光系统II (PSII)活性的影响
2.6.1 光系统II (PSII)供/受体侧变化 由图5可知, 相同施肥量条件下, 弱光环境(L2)中Wk、Vj显著升高, 表明弱光环境下叶片PSII供体侧与受体侧性能均有不同程度的降低。不同光照环境下, 花后结荚-成熟期(R3-R5) Wk、Vj均随施磷量的增加呈现降低的趋势。但不同光照环境下其降低幅度不一致, R3时期, 自然光照(L1)环境下正常施磷(P1)与增施磷肥(P2)处理的Wk和Vj, 较不施磷处理分别降低3.0%、9.5%和3.9%、10.5%; 弱光环境下P1与P2处理较P0处理则降低6.18%、12.4%和8.1%、15.9% (图5-A~D)。可见, 施磷后大豆供体侧和受体侧性能变化与光合速率变化趋势相一致, 虽然L2环境下大豆植株供、受体侧性能较弱但是正常施磷与增施磷肥后其改善幅度相比于L1环境下较大, 而且提高的幅度随着施磷量的增加明显大于自然光照下。与此同时, 2种光照环境下施磷后对Vj的影响更显著(图5-E, F), 表明PSII电子传递性能的提高可能是磷肥提高光合速率的主要原因。图5
新窗口打开|下载原图ZIP|生成PPT图5不同施磷量和遮光处理对花后大豆叶片Wk与Vj及其相关性的影响
不同字母表示处理间差异在0.05水平差异显著。R1: 始花期; R3: 结荚初期; R5: 鼓粒初期; R7: 成熟初期。处理同
Fig. 5Effects of different phosphate fertilizer application and light environment treatments on Wk, Vj and their correlation in soybean leaf after anthesis
Different letters indicate significant differences among treatments at the 0.05 probability level. R1: beginning of flowering; R3: beginning of podding; R5: beginning of grain filling; R7: beginning of maturity. Treatments are the same as those given in
2.6.2 光系统II (PSII)反应中心性能 相同施肥量条件下, 弱光环境(L2)显著降低叶片最大光化学效率(φPo)和PSII吸收的用于电子传递效率的光能(φEo)。不同光照环境下, 花后各时期大豆叶片φPo、φEo随施磷量的增加呈增加的趋势(图6-A~D)。R3时期, 正常光照环境(L1)下正常施磷(P1)与增施磷肥(P2)处理的φPo和φEo, 较不施磷(P0)处理分别升高1.1%、1.6%和3.4%、8.8%, 弱光环境(L2)下P1与P2处理较P0处理分别升高1.0%、3.2%和9.9%、18.9%, 且升高幅度随生育期推进不断增加, 可见φPo的变化幅度不大, 而φEo对磷肥的施用反应更敏感, 且施用磷肥对弱光环境下大豆叶片φEo影响更显著(图6-E, F)。
图6
新窗口打开|下载原图ZIP|生成PPT图6不同施磷量和遮光处理对大豆花后叶片光系统II (PSII)反应中心性能及其相关性的影响
不同字母表示处理间差异在0.05水平差异显著。R1: 始花期; R3: 结荚初期; R5: 鼓粒初期; R7: 成熟初期。处理同
Fig. 6Effects of different phosphate fertilizer application and light environment treatments on reaction center performance of photosystem II and their correlation in soybean leaf after anthesis
Different letters indicate significant differences among treatments at the 0.05 probability level. R1: beginning of flowering; R3: beginning of podding; R5: beginning of grain filling; R7: beginning of maturity. Treatments are the same as those given in
3 讨论
叶片是光合作用对弱光最敏感的部位之一[26]。弱光下植物会增大叶面积, 同时通过提高单位面积叶绿素含量, 增加光能捕获, 提高光能利用率, 以维持光合能力, 进而适应弱光环境。本研究中, 弱光下植株净光合速率(Pn)和气孔导度(Gs)显著下降, 但胞间CO2浓度(Ci)大幅上升, 表明弱光环境下光合速率的降低是叶肉光合机构的变化等非气孔限制因素导致的。适应该环境其单株叶面积(LA)与比叶面积(SLA)显著增加, 同时伴随着叶片中叶绿素a (Chl a)与叶绿素b (Chl b)的增加, 但净光合速率(Pn)显著下降, 表明叶绿素的上升不足以补偿光照强度的下降导致的光合速率下降。而施用磷肥后叶片SLA、Chl a、Chl b和Pn均显著增加, 尤以弱光环境(L1)下显著, 表明施用磷肥后植株可以提高叶面积和增加叶片中叶绿素含量, 通过增加光截获来提高叶片光合速率。以往的研究也表明磷肥与叶面积正相关[27], 对作物叶片光合速率有显著影响, 缺磷条件下光合速率显著降低[28,29], 与本研究一致。弱光抑制光合速率主要是通过影响光反应实现的。光系统II(PSII)是光化学反应的首要位点, 具有吸收和转化光能为电能的功能, 其性能高低决定了后续用于羧化反应的化学能的多少。快速叶绿素荧光诱导动力学OJIP曲线可以反应PSII原初光化学反应的过程和状态, PSII最大光化学效率(φPo)是衡量各种环境胁迫下PSII活性的重要参数[30], 本试验发现, 自然光照(L1)与弱光环境(L2)中施磷前后φPo的变化<5%。因此, 仅依据光系统II最大光化学效率判断施用磷肥对弱光环境下大豆光合速率的影响似乎很小。但是在弱光条件下, 相较于P1、P2处理, P0处理大豆OJIP曲线中J点(2 ms)的相对荧光产量有明显增加, 说明QA向QB电子传递不畅, 即PSII受体侧电子传递受阻。此外, 本研究还观察到P0处理K点的相对荧光产量也呈显著增加趋势, 但是不及J点差异明显, 同时发现Wk的变化比Vj的变化更小, 证明施用磷肥可以提升PSII供体侧放氧复合物的活性, 但是磷肥对PSII受体侧影响更显著, 且影响幅度随磷肥用量的提升而增加。为进一步探究磷肥对光合机构活性的影响, 本研究比较了不同处理PSII吸收的光能用于电子传递的效率(φEo), 即电子传递效率。L1与L2环境下, 施用磷肥与增施磷肥后φEo显著升高, L2环境下升高幅度显著高于L1环境下, 且其幅度随施肥量的增加呈上升趋势, 其变化趋势与花后光合速率的变化趋势一致, 表明弱光环境下增施磷肥后光合速率的大幅增加与PSII电子传递性能的提升关系密切。因此, 本研究认为弱光环境下施用磷肥与增施磷肥显著影响了PSII的电子传递活性, 且同时涉及其供体侧和受体侧性能的提高, 尤其对受体侧性能影响更显著。
因此, 本研究认为, 虽然弱光环境下大豆净光合速率与产量显著下降, 但是增施磷肥可以大幅度提高大豆叶面积与叶片中叶绿素含量, 从而使光能截获和利用效率显著升高, 同时提高PSII电子供体侧和受体侧性能, 增强电子传递效率, 促进光合作用, 有效提高弱光环境下光合产物向籽粒转运, 进而显著增加单株有效荚数和单株粒数, 最终提高产量。
4 结论
光照环境是决定大豆叶片光合碳同化速率以及产量的关键因素, 增施磷肥有利于大豆叶片光合能力稳定与产量增加, 尤其在弱光下效果更加明显。这主要是因为弱光环境中增施磷肥可以通过增加叶面积和叶绿素含量, 提高叶片对光能的截获, 提高光系统II电子供、受体侧性能, 促进电子传递效率, 改善弱光环境中光化学效率与电子传递的协同性, 进而缓解弱光导致的光合速率和产量的衰减。因此, 在夏季高光强时数趋于降低的现状下, 合理增施磷肥有利于改善夏大豆对光能的利用效率, 是保障大豆稳产、高产的有效途径之一。参考文献 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子
DOI:10.1016/j.scienta.2017.07.053URL [本文引用: 1]
DOI:10.1016/j.scienta.2019.02.005URL [本文引用: 1]
DOI:10.11676/qxxb2005.090URL [本文引用: 1]
采用国家基准气候站和基本气象站的地面资料，系统地分析了中国大陆地区1951年以来近地表主要气候要素演化的时间和空间特征。结果表明，中国近50 a来年平均地表气温变暖幅度约为1.1 ℃，增温速率接近0.22 ℃/（10 a），比全球或半球同期平均增温速率明显偏高。地表气温增暖主要发生在最近的20余年，其季节和空间特征与前人分析结论基本一致。降水量变化趋势对所取时间段和区域范围敏感。1951年以来全国平均降水量变化趋势不明显，但1956年以来略有增加。降水变化的空间特征明显而相对稳定，东北北部、包括长江中下游的东南部地区和西部广大地区降水增加，而华北地区以及东北东南部和西北东部地区降水明显减少。分析还发现，近50 a来全国平均的日照时数、平均风速、水面蒸发等气候要素均呈显著下降趋势，但积雪地带的最大积雪深度却有所增加。中国日照时间和水面蒸发量变化的空间特征很相似，减少最明显的地区均发生在华北和华东，新疆次之。影响中国年代以上尺度气候变化的因子错综复杂，人类活动引起的大气中温室气体浓度增高可能在一定程度上影响了中国近50 a来的气候，但考虑到尚存的不确定性，目前仍不能给出明确结论。中国东部大部分地区日照时间和水面蒸发量减少可能均起源于人为排放的气溶胶影响，平均风速减弱也有利于水面蒸发量下降，而在西部地区云量和降水量的变化可能更重要。
DOI:10.11676/qxxb2005.090URL [本文引用: 1]
采用国家基准气候站和基本气象站的地面资料，系统地分析了中国大陆地区1951年以来近地表主要气候要素演化的时间和空间特征。结果表明，中国近50 a来年平均地表气温变暖幅度约为1.1 ℃，增温速率接近0.22 ℃/（10 a），比全球或半球同期平均增温速率明显偏高。地表气温增暖主要发生在最近的20余年，其季节和空间特征与前人分析结论基本一致。降水量变化趋势对所取时间段和区域范围敏感。1951年以来全国平均降水量变化趋势不明显，但1956年以来略有增加。降水变化的空间特征明显而相对稳定，东北北部、包括长江中下游的东南部地区和西部广大地区降水增加，而华北地区以及东北东南部和西北东部地区降水明显减少。分析还发现，近50 a来全国平均的日照时数、平均风速、水面蒸发等气候要素均呈显著下降趋势，但积雪地带的最大积雪深度却有所增加。中国日照时间和水面蒸发量变化的空间特征很相似，减少最明显的地区均发生在华北和华东，新疆次之。影响中国年代以上尺度气候变化的因子错综复杂，人类活动引起的大气中温室气体浓度增高可能在一定程度上影响了中国近50 a来的气候，但考虑到尚存的不确定性，目前仍不能给出明确结论。中国东部大部分地区日照时间和水面蒸发量减少可能均起源于人为排放的气溶胶影响，平均风速减弱也有利于水面蒸发量下降，而在西部地区云量和降水量的变化可能更重要。
DOI:10.3724/SP.J.1006.2013.00478URL [本文引用: 1]
以郑单958和振杰2号为试验材料，大田条件下设置花粒期遮阴(S1)、穗期遮阴(S2)、全生育期遮阴(S3) 3个处理，遮光度为60%，以自然光照为对照，研究遮阴对夏玉米光合特性和叶黄素循环的影响。结果表明，遮阴后夏玉米产量显著降低，且遮阴时期对产量的影响表现为S3>S1>S2，郑单958和振杰2号的S3分别减产96.87%和90.78%。遮阴后叶片的光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、叶绿体色素含量显著降低，胞间CO2浓度(Ci)较同期对照先降低后升高，即叶片光合作用的降低受到气孔与非气孔因素双重影响，2个供试品种变化一致。遮阴期间光合电子传递量子效率(ФPSII)降低，原初光能转换效率(Fv/Fm)和非光化学猝灭(NPQ)显著升高，叶黄素循环库(A+Z+V)和脱环化状态(A+Z)/(A+Z+V)升高，即在长期遮阴条件下叶片捕获的光能分配发生了变化，光合电子传递的能量占吸收光能的比例降低，叶黄素循环的启动辅助过剩光能的热耗散。遮阴结束初期(A+Z)/(A+Z+V)和NPQ迅速升高，说明光恢复初期叶片对弱光适应后的自然光照比较敏感，叶黄素循环增强抑制强光对光合机构的破坏。
DOI:10.3724/SP.J.1006.2013.00478URL [本文引用: 1]
以郑单958和振杰2号为试验材料，大田条件下设置花粒期遮阴(S1)、穗期遮阴(S2)、全生育期遮阴(S3) 3个处理，遮光度为60%，以自然光照为对照，研究遮阴对夏玉米光合特性和叶黄素循环的影响。结果表明，遮阴后夏玉米产量显著降低，且遮阴时期对产量的影响表现为S3>S1>S2，郑单958和振杰2号的S3分别减产96.87%和90.78%。遮阴后叶片的光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、叶绿体色素含量显著降低，胞间CO2浓度(Ci)较同期对照先降低后升高，即叶片光合作用的降低受到气孔与非气孔因素双重影响，2个供试品种变化一致。遮阴期间光合电子传递量子效率(ФPSII)降低，原初光能转换效率(Fv/Fm)和非光化学猝灭(NPQ)显著升高，叶黄素循环库(A+Z+V)和脱环化状态(A+Z)/(A+Z+V)升高，即在长期遮阴条件下叶片捕获的光能分配发生了变化，光合电子传递的能量占吸收光能的比例降低，叶黄素循环的启动辅助过剩光能的热耗散。遮阴结束初期(A+Z)/(A+Z+V)和NPQ迅速升高，说明光恢复初期叶片对弱光适应后的自然光照比较敏感，叶黄素循环增强抑制强光对光合机构的破坏。
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DOI:10.1016/S2095-3119(16)61525-3URL [本文引用: 1]
DOI:10.1016/j.plaphy.2017.02.011URLPMID:28236752 [本文引用: 1]
Responses of electron transport to three levels of irradiation (20, 200, and 1200?μmol photons m-2?s-1 PAR; exposures called LL, ML and HL, respectively) were investigated in eelgrass (Zostera marina L.) utilizing the chlorophyll a fluorescence technique. Exposure to ML and HL reduced the maximum quantum yield of photosystem II (PSII) (Fv/Fm) and the maximum slope decrease of MR/MRO (VPSI), indicating the occurrence of photoinhibition of both PSII and photosystem I (PSI). A comparatively slow recovery rate of Fv/Fm due to longer half-life recovery time of PSII and 40% lower descending amplitude compared to other higher plants implied the poor resilience of the PSII. Comparatively, PSI demonstrated high resilience and cyclic electron transport (CEF) around PSI maintained high activity. With sustained exposure, the amplitudes of the kinetic components (L1 and L2), the probability of electron transfer from PSII to plastoquinone pool (ψET2o), and the connectivity among PSII units decreased, accompanied by an enhancement of energy dissipation. Principle component analysis revealed that both VPSI and Fv/Fm contributed to the same component, which was consistent with high connectivity between PSII and PSI, suggesting close coordination between both photosystems. Such coordination was likely beneficial for the adaption of high light. Exposure to LL significantly increased the activity of both PSI and CEF, which could lead to increased light harvesting. Moreover, smooth electron transport as indicated by the enhancement of L1, L2, ψET2o and the probability of electron transport to the final PSI acceptor sides, could contribute to an increase in light utilization efficiency.
DOI:10.3389/fpls.2018.00250URLPMID:29599786 [本文引用: 1]
Understanding the biotic and abiotic factors that influence the susceptibility of a community to invasion is beneficial for the prediction and management of invasive species and the conservation of native biodiversity. However, the relationships between factors and invasibility of a community have not been fully confirmed, and the factors most associated with the susceptibility of a community to invasion have rarely been identified. In this study, we investigated the species richness patterns in aquatic exotic and native plants and the relationships of exotic species richness with habitat and water environment factors in 262 aquatic plant communities in China. A total of 11 exotic plant species were recorded in our field survey, and we found neither a negative nor a positive relationship between aquatic exotic and native plant species richness. The aquatic exotic plant species richness is negatively correlated with the relative coverage and biomass of native plants but positively correlated with the total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations in the water. The native plant species richness, native species' relative coverage, and native species' biomass were positively related to each other, whereas the TP, TN, and COD were also positively related to each other. The native plant species richness, native species' relative coverage, and native species biomass were each negatively correlated with the TP, TN, and COD. In addition, biotic rather than abiotic predictors accounted for most of the variation in exotic plant richness. Our results suggest that improving the vegetation coverage and the biodiversity of native plants is the most effective approach for preventing alien plant invasions and minimizing their impacts on freshwater ecosystems.
DOI:10.1016/S2095-3119(13)60670-XURL [本文引用: 1]
DOI:10.1016/j.scitotenv.2018.12.182URLPMID:30580217 [本文引用: 1]
Titanium (Ti) is considered an essential element for plant growth; however, its role in crop performance through stimulating the activities of certain enzymes, enhancing chlorophyll content and photosynthesis, and improving crop morphology and growth requires more study. We therefore conducted a laboratory experiments to study the effects of ionic Ti application on morphology, growth, biomass distribution, chlorophyll fluorescence performance and Rubisco activity of soybean (Glycine max L.) under normal light (NL) and shade conditions (SC). In this study, we sprayed soybean plants with five different levels of ionic Ti (T1?=?0, T2?=?1.25, T3?=?2.5, T4?=?5 and T5?=?10?mg Ti Plant-1) through foliar application method. Our results show that with increasing moderate (2.5?mg Ti Plant-1) Ti concentration, the chlorophyll pigments (chlorophyll [Chl] a, b, carotenoid [Car]), plant biomass, photochemical efficiency of photosystem II (Fv/Fm), and electron transport rate (ETR) of soybean increased, but higher levels (5-10?mg Ti Plant-1), resulted in leaf anatomical and chloroplast structural disruptions under both NL and SC. Soybean plants showed maximum biomass, leaf area, leaf thickness, Chl a, b, Car, Rubisco activity, Fv/Fm and ETR for T3 at 2.5?mg Ti Plant-1; however, declined significantly for T5 at high concentration of 10?mg Plant-1. In NL, the application of 2.5?mg Ti Plant-1 (T3) increased the Chl a, b, and total Chl contents 40, 20, and 27% as compared to control treatment (T1). In SC, the application of 1.25?mg?Ti?mg Plant-1 (T2) increased the Chl a, b, and total Chl contents 38, 19, and 14% as compared to control treatment. In NL, the Fv/Fm, qP, PSII, and ETR were higher in the T3 treatment over the T1 (control) by 7, 0.3, 16, and 16%, respectively. In SC, the Fv/Fm, qP, PSII, and ETR were higher in the T3 treatment over the T1 (control) by 5, 5, 19, and 19%, respectively. Moreover, Rubisco activity was at peak (55 and 6% increase under NL and SC) at 2.5?mg Ti Plant-1and decreased with increasing Ti concentration, reaching the lowest at 10?mg Ti Plant-1, which indicates that leaf cells were damaged as observed in the leaf anatomy. We concluded that ionic Ti expresses a hormesis effect: at lower concentrations, promoting soybean growth, however, at higher concentrations, suppressing soybean growth both under NL and SC. We therefore suggest that under different light stress conditions, Ti application could serve to mitigate abiotic stresses, especially in intercropping systems.
DOI:10.3724/SP.J.1006.2019.83040URL [本文引用: 1]
玉米-大豆带状套作模式下, 宽窄行种植玉米, 窄行叶片存在着明显的光限制现象。采用低(A1: 众望玉18)、中(A2: 川单418)、高(A3: 荣玉1210)光效玉米品种, 玉米-大豆带状套作种植模式, 带宽固定为2 m, 每带种植2行玉米2行大豆, 设置大豆行距40 cm和玉米不同的窄行行距(B1: 20 cm; B2: 40 cm; B3: 单作)。探究套作高光效玉米窄行穂位叶在不同窄行光胁迫下的光合指标差异。结果表明, 与低光效和中光效品种玉米相比, 套作常规行距(40 cm)下, 高光效玉米品种(荣玉1210)窄行穗位叶光合速率、PEPCase活性分别显著高出46.9%、230.1%和11.8%、13.98%; 对弱光(10:00前、16:00后)的利用效率及叶绿体结构完整程度较高, 而叶绿素初始荧光(Fo)和最大荧光(Fm)较低; 随套作窄行行距减小, 3类品种玉米窄行穗位叶光合速率、光合作用关键酶活性均呈下降趋势, 叶绿素初始荧光(Fo)、最大荧光(Fm)及有效光化学量子产量(Fv'/Fm')均呈现不同程度的升高, 但均以套作高光效玉米变化幅度最小。套作高光效玉米在套作环境中窄行穗位叶的光合速率、光合作用关键酶活性、产量与单作差异均未达显著水平, 而低光效玉米和中光效玉米套作与单作相比, 光合速率、PEPCase活性显著降低28.9%、24.2%和7.4%、5.5%。因此, 不同玉米品种适应套作窄行光胁迫的能力差异显著, 套作高光效玉米(荣玉1210)在套作条件下仍具有相对理想的光合生理指标, 这为其适应套作光环境并获得高产提供了理论依据。
DOI:10.3724/SP.J.1006.2019.83040URL [本文引用: 1]
玉米-大豆带状套作模式下, 宽窄行种植玉米, 窄行叶片存在着明显的光限制现象。采用低(A1: 众望玉18)、中(A2: 川单418)、高(A3: 荣玉1210)光效玉米品种, 玉米-大豆带状套作种植模式, 带宽固定为2 m, 每带种植2行玉米2行大豆, 设置大豆行距40 cm和玉米不同的窄行行距(B1: 20 cm; B2: 40 cm; B3: 单作)。探究套作高光效玉米窄行穂位叶在不同窄行光胁迫下的光合指标差异。结果表明, 与低光效和中光效品种玉米相比, 套作常规行距(40 cm)下, 高光效玉米品种(荣玉1210)窄行穗位叶光合速率、PEPCase活性分别显著高出46.9%、230.1%和11.8%、13.98%; 对弱光(10:00前、16:00后)的利用效率及叶绿体结构完整程度较高, 而叶绿素初始荧光(Fo)和最大荧光(Fm)较低; 随套作窄行行距减小, 3类品种玉米窄行穗位叶光合速率、光合作用关键酶活性均呈下降趋势, 叶绿素初始荧光(Fo)、最大荧光(Fm)及有效光化学量子产量(Fv'/Fm')均呈现不同程度的升高, 但均以套作高光效玉米变化幅度最小。套作高光效玉米在套作环境中窄行穗位叶的光合速率、光合作用关键酶活性、产量与单作差异均未达显著水平, 而低光效玉米和中光效玉米套作与单作相比, 光合速率、PEPCase活性显著降低28.9%、24.2%和7.4%、5.5%。因此, 不同玉米品种适应套作窄行光胁迫的能力差异显著, 套作高光效玉米(荣玉1210)在套作条件下仍具有相对理想的光合生理指标, 这为其适应套作光环境并获得高产提供了理论依据。
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DOI:10.1016/j.fcr.2016.01.012URL [本文引用: 1]
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DOI:10.11674/zwyf.2010.0335URL [本文引用: 1]
采用溶液培养方法，研究了磷水平（0、 10、 100、 500 和1000 μmol/L）对不同磷效率小麦（西农979和小偃6号）幼苗基部第1叶叶绿素荧光参数与叶绿素含量的影响。结果表明，随着磷水平的增加，两小麦幼苗基部第1叶的叶绿素a荧光参数均表现出先升高后降低的趋势，不同的是小偃6号在磷水平为100 μmol/L 时就达到了峰值，而西农979的最大值则出现在500 μmol/L磷水平下。说明小偃6号（磷高效）的光能转换效率和电子传递效率高于西农979，且受低磷胁迫的影响较小。
DOI:10.11674/zwyf.2010.0335URL [本文引用: 1]
采用溶液培养方法，研究了磷水平（0、 10、 100、 500 和1000 μmol/L）对不同磷效率小麦（西农979和小偃6号）幼苗基部第1叶叶绿素荧光参数与叶绿素含量的影响。结果表明，随着磷水平的增加，两小麦幼苗基部第1叶的叶绿素a荧光参数均表现出先升高后降低的趋势，不同的是小偃6号在磷水平为100 μmol/L 时就达到了峰值，而西农979的最大值则出现在500 μmol/L磷水平下。说明小偃6号（磷高效）的光能转换效率和电子传递效率高于西农979，且受低磷胁迫的影响较小。
DOI:10.3724/SP.J.1258.2013.00104URL [本文引用: 1]
揭示玉米(Zea mays)和花生(Arachis hypogaea)间作提高花生对弱光利用能力的光合特点及磷(P)肥效应, 对阐明间作花生适应弱光的光合机理和提高间作花生的产量具有重要意义。该试验于2011–2012年在河南科技大学试验农场分析了间作花生功能叶的叶绿素含量与构成、光响应曲线和CO2响应曲线特点和荧光参数。结果表明: 与单作花生相比, 施P与不施P条件下玉米和花生间作显著(p < 0.01)提高了花生功能叶的叶绿素b含量, 降低了叶绿素a/b, 显著提高了光系统II最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSII)、光化学猝灭系数(qP)、表观量子效率(AQY)和弱光时的光合速率, 显著降低了气孔导度、二磷酸核酮糖羧化酶羧化速率(Vcmax)、电子传递速率(Jmax)和磷酸丙糖利用速率(TPU); 与不施P相比, 施P有利于提高间作花生功能叶的叶绿素含量, 显著提高了ΦPSII、qP、Vcmax、Jmax和TPU, 说明间作花生通过提高功能叶的叶绿素b含量, 改变叶绿素构成, 提高了光系统II的Fv/Fm、ΦPSII和qP, 增强了对光能的捕获和转化能力, 提高了对弱光的利用能力, 而并非提高了对CO2的羧化固定能力; 施P有利于提高间作花生对弱光的利用能力和产量, 土地当量比提高了6.2%–9.3%。
DOI:10.3724/SP.J.1258.2013.00104URL [本文引用: 1]
揭示玉米(Zea mays)和花生(Arachis hypogaea)间作提高花生对弱光利用能力的光合特点及磷(P)肥效应, 对阐明间作花生适应弱光的光合机理和提高间作花生的产量具有重要意义。该试验于2011–2012年在河南科技大学试验农场分析了间作花生功能叶的叶绿素含量与构成、光响应曲线和CO2响应曲线特点和荧光参数。结果表明: 与单作花生相比, 施P与不施P条件下玉米和花生间作显著(p < 0.01)提高了花生功能叶的叶绿素b含量, 降低了叶绿素a/b, 显著提高了光系统II最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSII)、光化学猝灭系数(qP)、表观量子效率(AQY)和弱光时的光合速率, 显著降低了气孔导度、二磷酸核酮糖羧化酶羧化速率(Vcmax)、电子传递速率(Jmax)和磷酸丙糖利用速率(TPU); 与不施P相比, 施P有利于提高间作花生功能叶的叶绿素含量, 显著提高了ΦPSII、qP、Vcmax、Jmax和TPU, 说明间作花生通过提高功能叶的叶绿素b含量, 改变叶绿素构成, 提高了光系统II的Fv/Fm、ΦPSII和qP, 增强了对光能的捕获和转化能力, 提高了对弱光的利用能力, 而并非提高了对CO2的羧化固定能力; 施P有利于提高间作花生对弱光的利用能力和产量, 土地当量比提高了6.2%–9.3%。
DOI:10.1016/j.jplph.2016.12.006URLPMID:28040624 [本文引用: 1]
The efficient and fluent operation of photosynthesis in plants relies on activity of pigment-protein complexes called antenna, absorbing light and transferring excitations toward the reaction centers. Here we show, based on the results of the fluorescence lifetime imaging analyses of single chloroplasts, that pigment-protein complexes, in dark-adapted plants, are not able to act effectively as photosynthetic antennas, due to pronounced, adverse excitation quenching. It appeared that the antenna function could be activated by a short (on a minute timescale) illumination with light of relatively low intensity, substantially below the photosynthesis saturation threshold. The low-light-induced activation of the antenna function was attributed to phosphorylation of the major accessory light-harvesting complex LHCII, based on the fact that such a mechanism was not observed in the stn7 Arabidopsis thaliana mutant, with impaired LHCII phosphorylation. It is proposed that the protein phosphorylation-controlled change in the LHCII clustering ability provides mechanistic background for this regulatory process.
DOI:10.1016/j.ecolind.2017.03.010URL [本文引用: 1]
DOI:10.1016/j.fcr.2018.01.031URL [本文引用: 1]
DOI:10.1161/01.hyp.11.6.591URLPMID:2839415 [本文引用: 1]
The presence of angiotensinogen messenger RNA (mRNA) was detected in rat vascular and adipose tissue. Angiotensinogen mRNA in rat aorta was localized in the adventitia and surrounding adipose tissue, and not in the vascular smooth muscle. Freshly dispersed and cultured endothelial and aortic smooth muscle cells did not contain detectable amounts of angiotensinogen mRNA. In addition to periaortic adipose tissue, angiotensinogen mRNA was present in other fat depots of both brown and white types. To examine regulation of angiotensinogen gene expression, Sprague-Dawley rats were treated with angiotensin converting enzyme inhibitor or underwent bilateral nephrectomy. Relative levels of angiotensinogen mRNA in brown adipose tissues increased dramatically by 48 hours after bilateral nephrectomy. However, only one source of brown adipose tissue showed increased angiotensinogen mRNA levels after animals were treated for 5 days with converting enzyme inhibitor. In addition, angiotensinogen was released into the medium from incubated adipose tissues with levels increasing over a 2-hour period. These results demonstrate that angiotensinogen is synthesized by adipose tissue in the rat and may play a role in the function of this tissue.
DOI:10.1016/j.scienta.2015.09.009URL
DOI:10.1071/FP03032URL [本文引用: 1]
DOI:10.1016/j.saa.2018.09.036URLPMID:30282060 [本文引用: 1]
Lichens are successful colonizers in extreme environments worldwide, and they are considered to have played an important role during the evolution of life. Here, we have used a correlative approach, combining three optical signals (chlorophyll a fluorescence (ChlF), reflectance, and Raman spectra), to monitor hydration induced changes in photosynthetic properties of an Antarctic chlorolichen Dermatocarpon polyphyllizum. We measured these three signals from this lichen at different stages (after 4?h, 24?h, and 48?h) of hydration, and compared the data obtained from this lichen in "dry state" as well as in different "hydrated state". We found that dry state of this lichen has: (1) no variable ChlF, (2) high reflectance, with no red-edge and almost zero photochemical reflectance index (PRI), and (3) low-intensity Raman bands of their carotenoids. Furthermore, 4?h of hydration, increased its relative water content (RWC) by 93%, showed red-edge in reflectance spectra, and changed the maximum quantum yield of PSII photochemistry (Fv/Fm) from 0 to 0.57?±?0.01. We found that reflectance indices, normalized difference index (NDVI) and PRI, significantly differed between brown and black/green surface areas, at all hydration stages; whereas, a shift in the Raman ν1(CC) band, between brown and black/green surface areas, occurred in 24?h or 48?h hydrated samples. These data indicate that hydration shortly (within 4?h) activated functions of photosynthetic apparatus, and the de novo synthesis of carotenoids occured in 24?h or 48?h. Furthermore, exposure to high irradiance (2000?μmol?photons?m-2?s-1), in 48?h hydrated lichen, significantly reduced Fv/Fm (signifies photoinhibition) and increased PRI (represents changes in xanthophyll pigments). We conclude that the implication of such a correlative approach is highly useful for understanding survival and protective mechanisms on extremophile photosynthetic organisms.
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DOI:10.1023/A:1004877111238URL [本文引用: 1]
Biomass accumulation by crops depends both on light interception by leaves and on the efficiency with which the intercepted light is used to produce dry matter. Our aim was to identify which of these processes were affected for maize (Zea Mays L., cv Volga) field crops grown under phosphorus (P) deficiency, and assess their relative importance. In this paper, the effects of P deficiency on leaf appearance, leaf elongation rate, final individual leaf area and leaf senescence were studied. The experimental work was carried out in 1995–1977 on a long-term P fertilisation trial located on a sandy soil in the south-west of France. Three P fertilisation regimes have been applied since 1972: no-P (P0 treatment) and different rates of P fertiliser (P1.5:1.5 times the grain P export and P3:3 times the grain P export). These fertilisation regimes have led to contrasted levels of soil P supply, with the P0 treatment being limiting for growth. Very few differences were observed about leaf growth between the P1.5 and P3 treatments. Conversely, the leaf area index (LAI) was significantly reduced in the P0 treatment, especially during the first phases of the crop cycle (up to −60% between the 7- and 14-visible leaves). This effect gradually decreased over time. The lower LAI in P0 treatment was due to two main processes affecting the leaf growth. The final number of leaves per plant and leaf senescence were only slightly modified by P deficiency. Conversely, leaf appearance was delayed during the period between leaf 4 and leaf 9. The value of the phyllochron increased from 47 °C days in the P1.5 treatment to 65 °C days in the P0 treatment. Leaf elongation rates during the quasi-linear phase of leaf expansion were significantly reduced for lower leaves of P0 plants. The final size of leaves L2–L12 was reduced. On the opposite, leaf elongation duration was not greatly affected by P treatments. Before the emergence of leaf 9, the reduction of individual leaf size was the main factor responsible for the reduced LAI in the P0 treatment. After this stage, the delayed leaf appearance accounted for a great part of the reduced LAI in the P0 treatment.
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DOI:10.1155/2019/9058715URLPMID:31534966 [本文引用: 1]
Although the physiological and molecular responses of Citrus to Al-toxicity or low pH have been examined in some details, little information is available on Citrus responses to pH and aluminum (Al) interactions. Citrus sinensis seedlings were irrigated for 18 weeks with nutrient solution at a concentration of 0 or 1 mM AlCl3?6H2O and a pH of 2.5, 3.0, 3.5, or 4.0. Thereafter, biomass, root, stem, and leaf concentrations of Al and nutrients, leaf gas exchange, chlorophyll a fluorescence (OJIP) transients, and related parameters were investigated to understand the physiological mechanisms underlying the elevated pH-induced alleviation of Citrus toxicity. Increasing the nutrient solution pH from 2.5 to 4.0 alleviated the Al-toxic effects on biomass, photosynthesis, OJIP transients and related parameters, and element concentrations, uptake, and distributions. In addition, low pH effects on the above physiological parameters were intensified by Al-toxicity. Evidently, a synergism existed between low pH and Al-toxicity. Increasing pH decreased Al uptake per root dry weight and its concentration in roots, stems, and leaves and increased nitrogen, phosphorus, calcium, magnesium, sulfur, and boron uptake per plant and their concentrations in roots, stems, and leaves. This might be responsible for the elevated pH-induced alleviation of growth inhibition and the impairment of the whole photosynthetic electron transport chain, thus preventing the decrease of CO2 assimilation.
DOI:10.1093/pcp/pcu061URL [本文引用: 1]
Under field conditions, the leaves of plants are exposed to fluctuating light, as observed in sunfleck. The duration and frequency of sunfleck, which is caused by the canopy being blown by the wind, are in the ranges from 0.2 to 50 s, and from 0.004 to 1 Hz, respectively. Furthermore, > 60% of the sunfleck duration ranges from 0.2 to 0.8 s. In the present research, we analyzed the effects of repetitive illumination by short-pulse (SP) light of sunflower leaves on the photosynthetic electron flow. The duration of SP light was set in the range from 10 to 300 ms. We found that repetitive illumination with SP light did not induce the oxidation of P700 in PSI, and mainly inactivated PSI. Increases in the intensity, duration and frequency of SP light enhanced PSI photoinhibition. PSI photoinhibition required the presence of O-2. The inactivation of PSI suppressed the net CO2 assimilation. On the other hand, the increase in the oxidized state of P700 suppressed PSI inactivation. That is, PSI with a reduced reaction center would produce reactive oxygen species (ROS) by SP light, leading to PSI photodamage. This mechanism probably explains the PSI photodamage induced by constant light.
