,1,*, 李召虎1Morpho-physiological Responses of Cotton Shoot Apex to the Chemical Topping with Fortified Mepiquat Chloride
AN Jing1, LI Fang1, ZHOU Chun-Jiang2, TIAN Xiao-Li,1,*, LI Zhao-Hu1通讯作者:
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收稿日期:2018-05-6接受日期:2018-08-20网络出版日期:2018-09-19
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Received:2018-05-6Accepted:2018-08-20Online:2018-09-19
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安静, 黎芳, 周春江, 田晓莉, 李召虎. 增效缩节安化学封顶对棉花主茎生长的影响及其相关机制[J]. 作物学报, 2018, 44(12): 1837-1843. doi:10.3724/SP.J.1006.2018.01837
AN Jing, LI Fang, ZHOU Chun-Jiang, TIAN Xiao-Li, LI Zhao-Hu.
棉花打顶(或称摘心、掐尖)是我国各棉区普遍采用的一项整枝技术, 可控制棉株主茎生长, 避免出现无效果枝, 增加光合产物向果枝的运输[1], 还可防止倒伏、减轻虫害和烂铃[2,3,4]。目前棉花打顶仍以人工操作为主, 费工费时、劳动效率低, 制约了棉花生产轻简化、规模化、精准化和机械化作业[5,6]。自20世纪60年代, 国内逐渐开展棉花打顶机的相关研究, 但机械打顶对棉株的农艺性状、种植模式及整地质量要求较高, 易出现过打或漏打现象[7]。化学封顶是指利用植物生长调节剂强力延缓或抑制棉花顶芽生长, 控制棉花顶端优势, 从而达到调节营养生长与生殖生长的目的[5]。与人工打顶和机械打顶相比, 化学封顶简单方便、劳动强度低, 且有效避免了人工打顶和机械打顶易出现的物理伤害、时间跨度大、漏打和重复打顶等问题[5]。
缩节安(1,1-二甲基哌啶鎓; 1,1-dimethyl piperidinium chloride, DPC)是在国内外棉花生产中广泛应用的植物生长延缓剂, 从种子萌发开始至打顶后多次施用DPC的“系统化控”技术是我国棉花生产的常规管理措施[1,8]。增效DPC (25% DPC水剂, 简称DPC+)较普通DPC可溶性粉剂的有效期长, 并可借助助剂中的成分对幼嫩组织表面形成轻微伤害[9,10,11], 起到化学封顶的作用[9,12-14], 但其作用机制尚不清晰。
本文在DPC“系统化控”的基础上应用化学封顶剂DPC+, 研究其对棉花主茎生长、顶芽解剖结构、氧化还原状态和开花等基因表达的影响, 旨在揭示DPC+化学封顶的形态、生理和分子机制, 从而为该技术的合理应用提供理论指导。
1 材料与方法
试验于2015年在北京市海淀区中国农业大学上庄实验站(40°08°N, 110°10°E)进行, 试验地土壤类型为潮土, 前茬作物为棉花。土壤基础肥力情况: 有机质6.96 g kg-1、pH 7.86、碱解氮21.10 mg kg-1、全氮0.46 g kg-1、速效磷6.96 mg kg-1、速效钾53.47 mg kg-1。供试棉花品种为欣试17, 由河北省河间市国欣农村技术服务总会提供。增效缩节安(DPC+)为25%水剂, 由北京市农业技术推广站和中国农业大学植物生长调节剂教育部工程研究中心共同研发, 由新疆金棉科技有限责任公司生产并提供。普通DPC为98%的可溶性粉剂, 由江苏润泽农化有限公司生产。1.1 试验设计
采用随机区组设计, 重复3次。化学封顶处理于棉花盛花期后(7月24日)施用DPC+, 剂量为1125 mL hm-2; 对照小区喷施清水。处理和对照在生育期间均进行常规DPC “系统化控”, DPC应用时间和剂量为苗期(6月3日) 7.5 g hm-2、蕾期(6月21日) 15 g hm-2、初花期(7月13日) 75 g hm-2、化学封顶后7 d (7月31日) 150 g hm-2。6行区, 行长7 m, 行距0.9 m, 小区面积37.8 m2。1.2 试验地管理
于2015年4月26日播种, 种植密度约6万株 hm-2。播前施基肥, 包括有机肥3750.0 kg hm-2、N (尿素) 153.0 kg hm-2、P2O5 (磷酸二铵) 82.8 kg hm-2和K2O (硫酸钾) 135.0 kg hm-2。盛花期追施N (尿素) 138.0 kg hm-2和K2O (硫酸钾) 120.0 kg hm-2。其他田间管理与当地大田生产一致。1.3 调查和取样方法
1.3.1 株高及白花以上节位(nodes above the last white flower, NAWF) 处理前在每小区挂牌标记10株代表性植株, 处理后定期调查株高及NAWF。1.3.2 顶芽解剖结构 于处理后0、3、6及11 d取样。从每小区选5株代表性植株, 取下顶芽并剥去外围幼叶, 将约0.5 cm长的顶芽放入FAA固定液, 真空抽气5 min。经梯度乙醇脱水、二甲苯透明和石蜡包埋后, 利用Leica RM2235石蜡切片机(Germany)切片, 厚度8 μm, 经粘片、脱蜡、番红-固绿对染、中性树脂封片等常规石蜡切片步骤制作成永久制片, 采用配备DP80 CCD的Olympus显微镜(Japan)观察和拍照。利用ImageJ/Fiji软件统计棉花顶芽生长点的长和高, 并计算其纵横比。
1.3.3 氧化还原状态 于处理后0、6、24、48、72和120 h取样。从每小区选4株代表性植株, 取顶芽部位(包括刚展开的新叶), 液氮速冻后于-40℃保存备用。
参照Sergiev方法[15]测定H2O2含量; 采用羟胺氧化的方法测定超氧阴离子自由基(O2-)含量; 利用与硫代巴比妥酸(TBA)显色反应测定丙二醛(MDA)含量[16]。
1.3.4 基因表达 于处理后0、6、24、48、72及120 h取样。从每小区选代表性植株3株, 取顶芽部位(不包括刚展开的新叶), 液氮速冻后于-80℃保存备用。
用植物RNA提取试剂盒(艾德莱, 北京)提取棉花叶片的总RNA, 用M-MLV反转录试剂盒(TaKaRa, Japan)合成cDNA。根据GhSPL3 (GenBank登录号为KJ622311.1)、GhV1 (GenBank登录号为GU929695)和GhREV3 (Cottongen CotAD_04603)基因序列设计qRT-PCR特异性引物, 以GhACT9 (GenBank登录号为AY305737.1)作为内参, 引物序列见表1。用SYBR green II荧光染料试剂盒(TaKaRa, Japan)进行qRT-PCR, 扩增条件为95℃ 30 s; 95℃ 5 s, 60℃ 35 s, 40个循环。采用2-ΔΔCT对基因的相对表达量进行分析。
Table 1
表1
表1qRT-PCR引物序列
Table 1
| 基因名称 Gene name | 引物序列 Primer Sequences (5'-3') | 基因序列来源 Gene source |
|---|---|---|
| GhSPL3 | F: AAGGAGGGTCCAGTACGGTG; R: CAGCCTTGGCATGGAACTCA | GenBank: KJ622311.1 |
| GhV1 | F: TGGGTGAGGGAGATGTCTGT; R: GGGCGGCATTTCATTGAGAC | GenBank: GU929695 |
| GhREV3 | F: TATTCCGGCGCTGCGCTATG; R: TGTTGCTCAAGCTCTTGCCG | Cottongen: CotAD_04603 |
| GhACT9 | F: GCCTTGGACTATGAGCAGGA; R: AAGAGATGGCTGGAAGAGGA | GenBank: AY305737.1 |
新窗口打开|下载CSV
1.4 数据统计
应用IBM SPSS Statistics 20软件统计分析数据, Microsoft Excel 2016软件作图。2 结果与分析
2.1 DPC+化学封顶对棉株生长的影响
用化学封顶剂DPC+处理7 d后, 棉株生长速度逐渐降低; 32 d后, 株高比对照低5.3 cm (图1和图2-A)。白花以上节位(nodes above the last white flower, NAWF)可以反映棉株生殖生长与营养生长的协调状况和熟期[17,18]。一般情况下, NAWF在初花期最高, 之后逐渐下降。当NAWF达到5.0时, 棉株进入生理成熟阶段(physiological cutout), 即棉株不再形成有效花[19]。DPC+化学封顶处理后, 棉株NAWF更早降到5, 表明其较早进入生理成熟期; 处理14 d和22 d后, NAWF分别为3.8和3.3, 同期对照的NAWF显著高于处理, 分别为4.3和4.4 (图2-B)。图1
新窗口打开|下载原图ZIP|生成PPT图1化学封顶剂DPC+对棉花株高的影响
比例尺: 10 cm。
Fig. 1Effect of chemical topping with DPC+ on cotton plant height
Scale bar: 10 cm.
图2
新窗口打开|下载原图ZIP|生成PPT图2化学封顶剂DPC+对棉花株高(A)及白花以上节位(B)的影响
误差线表示3次重复的标准误, *P < 0.05, ***P < 0.001。
Fig. 2Effect of chemical topping with DPC+ on plant height (A) and nodes above white flower (NAWF) (B)
Error bars represent standard error, n = 3 biological replicates, *P < 0.05, ***P < 0.001.
2.2 DPC+化学封顶对棉花顶芽解剖结构的影响
棉花的主茎顶端分生组织为近乎扁平的圆丘状, 棉株地上部的各类器官均由此分化发育形成[1,20]。由图3可知, 化学封顶剂DPC+处理后3 d, 棉株主茎生长点较对照趋于平缓, 生长点的纵横比与对照相比显著降低。此后对照棉株的生长点也较之前平缓、纵横比也开始下降, 这是棉株自身营养生长势减弱和DPC“系统化控”最后一次(化学封顶后7 d)施药共同作用的结果。但同期DPC+化学封顶生长点的形态仍较对照更扁平、纵横比仍低于对照, 其中处理后11 d差异显著。图3
新窗口打开|下载原图ZIP|生成PPT图3化学封顶剂DPC+对棉花顶芽生长点解剖结构的影响
误差线表示3次重复的标准误, *P<0.05。比例尺: 100 μm。
Fig. 3Effect of chemical topping with DPC+ on anatomy of cotton shoot apical meristem (SAM) (A), illustration of height and length of cotton SAM (B), and the ratio of height/length of cotton SAM (C)
Error bars represent standard error, n = 3 biological replicates, *P<0.05. Scale bar: 100 μm.
2.3 DPC+化学封顶对棉花顶芽氧化还原状态的影响
化学封顶处理后, 对照棉株顶芽中的O2-含量逐渐下降(图4-A), 但H2O2和MDA总体变化不大(图4-B, C)。与对照相比, DPC+化学封顶后6 h棉株顶芽的两种活性氧(reactive oxygen species, ROS)组份和MDA均升高, 其中O2-显著升高, 提示化学封顶导致棉株顶芽出现了短期的氧化胁迫。图4
新窗口打开|下载原图ZIP|生成PPT图4化学封顶剂DPC+对棉花顶芽氧化还原状态的影响
误差线表示3次重复的标准误, *P < 0.05。
Fig. 4Effect of chemical topping with DPC+ on content of O2- (A), hydrogen peroxide (H2O2) (B), and lipid peroxidation (MDA) (C) in cotton shoot apex
Error bars represent standard error, n = 3 biological replicates, *P < 0.05.
2.4 DPC+化学封顶对棉花顶芽中相关基因表达的影响
GhSPL3是一种转录因子, 在棉花花芽分化、生长阶段的转变和花器官的形成上起着重要作用[21]。GhV1属于B3类转录因子, 在棉花顶芽部位特异表达, 可能参与棉花花芽起始[22]。GhREV3属于HD-Zip III转录因子, 与REVOLUTA (REV)同源性最高, 该转录因子正调控植物顶芽分生组织、侧芽分生组织和花芽分生组织的起始及维持[23,24,25,26]。化学封顶后棉花顶芽中GhSPL3的表达量与对照相比降低, 其中在封顶后6 h和120 h显著低于对照(图5-A); GhV1和GhREV3的表达量在处理后6 h也显著低于对照(图5-B, C), 之后几天与对照差异不大。3 讨论
活性氧(ROS)是一类具有氧化能力的分子、离子和自由基, 包括超氧阴离子(O2-)、羟基自由基(?OH)、过氧化氢(H2O2)、单线态氧(1O2)等, 可参与调控植物的生长发育以及各种胁迫反应[27,28,29]。MDA是植物膜脂过氧化的产物, 其含量可以反映植物遭受逆境伤害的程度[16]。化学封顶剂DPC+中的助剂可对棉株顶芽造成轻微伤害[9,10,11], 这一方面可提高DPC的吸收速度、加大DPC的吸收量, 另一方面伤害本身也可延缓植株的生长。本研究中DPC+处理后6 h, 棉株顶芽的O2-、H2O2和MDA含量均高于对照, 表明DPC+化学封顶对棉株顶芽产生了短时的氧化刺激。这种刺激可能会影响棉花顶芽发育和开花等生长发育过程。GhSPL3基因在棉花顶芽和花中表达量最高[21], 在拟南芥中超表达GhSPL3, 转基因株系花期显著提前, 莲座叶数目显著降低, 茎生叶数目显著增加, 表明其参与了侧枝和花芽的分化[30]。GbHB1是海岛棉(Gossypium barbadense L.)的一个HD-Zip III转录因子家族成员, 与拟南芥REV同源, GbHB1基因在胚珠和茎中的表达量最高, 推测其可能参与棉花纤维发育的调控[31]。本课题组已克隆了陆地棉(Gossypium hirsutum L.)的GhREV3基因, 并应用VIGS (Virus-Induced Gene Silencing)技术证明该基因沉默后棉花顶芽发育逐渐停止(未发表数据)。本研究中, DPC+化学封顶后6 h, 棉株顶芽中参与花芽分化(GhSPL3)、花芽起始(GhV1)和顶端分生组织维持(GhREV3)的基因表达量下降, 提示棉株生长速度和花芽分化活性将减弱。
植株生理和分子水分上的改变, 通常引起形态变化。已有研究表明, DPC+化学封顶与对照相比, 上部主茎节间和果枝均明显缩短, 叶片也明显减小[10-11,32-33]。本研究发现, DPC+化学封顶后, 棉株高度低于对照, 且较对照更早进入生理成熟期。
上述结果在已有研究的基础上进一步揭示了棉花DPC+化学封顶的作用及其机制, 这有助于深化对该技术的理解, 也展现了其应用潜力。
4 结论
应用DPC+ (增效DPC)进行棉花化学封顶使顶芽在短时间内(6 h)内出现氧化应激反应, 并降低了控制主茎生长点发育和花芽分化基因的表达, 从而延缓了棉株的生长和花芽的产生, 实现了化学封顶。参考文献 原文顺序
文献年度倒序
文中引用次数倒序
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In sub-Saharan areas of Africa, cotton growers no longer cut the shoot tips from plants (topping), although manual topping was promoted at the start of the 20th century to improve yield and, surprisingly, to reduce pest incidence. In these areas, the bollworms Helicoverpa armigera H bner, Earias spp., and Diparopsis watersi Rothschild are responsible for the majority of cotton yield losses, and the use of pyrethroids has resulted in resistance in field populations of H. armigera. In the face of these problems and given the scarcity of literature on the effects of topping on pest control, we assessed bollworm infestation levels in 12 trials comparing manual topping and non-topping cotton plots in Mali over a six-year period (2002, 2003, and 2005 to 2008). Topping was performed at the emergence of the 15th sympodial branch or at 10 days after the first flower opening. Our results showed no significant difference in seed cotton yields between topped and non-topped cotton. Bollworm infestations (all species) were always lower on topped cotton and 7 out of 12 trials showed significantly lower infestations on topped cotton. In plots of topped cotton, we recorded an average of 56% fewer H. armigera larvae, 68% fewer Earias spp. larvae, and 71% fewer D. watersi larvae with respectively 5, 4, and 3 out of 12 trials with significant differences in favor of topping and no significant difference in favor of non-topping. To our knowledge, our study is the first to report decreases in D. watersi larval infestation with cotton topping. Further studies are required to understand the mechanisms involved in these effects and to ensure that topping is economically attractive for farmers.
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[本文引用: 1]
DOI:10.3864/j.issn.0578-1752.2016.13.005URL [本文引用: 3]
[目的]探讨黄河流域北部棉区应用缩节胺(1,1-dimethyl-piperidinium chloride,DPC)对棉花进行化学封顶的可行性.[方法]于2012-2014年在河北省河间市瀛州镇国欣科技园和北京市中国农业大学上庄实验站进行,共包括6个独立试验.供试棉花品种为国欣棉3号(GX3)、欣抗4号(XK4)、石抗126(S126)和欣试17 (XS17).DPC化学封顶技术分为单独应用常规DPC化控技术(简称DPC)、将常规DPC化控技术与增效型DPC(简称DPC+)相结合(简称DPC+DPC+)两种方式,以在常规DPC化控基础上进行人工打顶(简称DPC+MT)为对照.[结果]2012和201 3年花铃期(7-8月份)多雨,应用DPC化学封顶技术的棉株较高、新生果枝数较多,其中株高较DPC+MT增加10.6-12.3 cm,果枝数增加5.8-7.9台.2014年花铃期干旱少雨,DPC化学封顶的株高与DPC+MT相比无显著差异,新生果枝数不超过3台.DPC化学封顶对棉花产量的影响不显著,但可发现2012年DPC+DPC+的产量表现出降低趋势,且上部果枝成铃少、新生果枝成铃多,群体熟期有推迟现象.2013和2014年DPC+DPC+的产量和熟期则与对照相当或略有增减.DPC+的应用时间(7月中旬至7月底)和剂量(750-1 500 mL.hm-2)对棉花株型及产量的影响无显著差异,但应避免在结铃盛期(7月底)应用大剂量DPC+(1 500 mL·hm-2),以防延长后期棉铃的成熟.与DPC+DPC+相比,单独应用常规DPC化控技术进行化学封顶在多雨年份或高密度下对棉株的控长强度较弱,而且存在减产风险.[结论]应用DPC进行化学封顶在黄河流域北部棉区基本可行,实际应用时需要根据气象因子和种植密度决定单独应用常规DPC化控技术还是将常规DPC化控技术与增效型DPC的应用相结合.
DOI:10.3864/j.issn.0578-1752.2016.13.005URL [本文引用: 3]
[目的]探讨黄河流域北部棉区应用缩节胺(1,1-dimethyl-piperidinium chloride,DPC)对棉花进行化学封顶的可行性.[方法]于2012-2014年在河北省河间市瀛州镇国欣科技园和北京市中国农业大学上庄实验站进行,共包括6个独立试验.供试棉花品种为国欣棉3号(GX3)、欣抗4号(XK4)、石抗126(S126)和欣试17 (XS17).DPC化学封顶技术分为单独应用常规DPC化控技术(简称DPC)、将常规DPC化控技术与增效型DPC(简称DPC+)相结合(简称DPC+DPC+)两种方式,以在常规DPC化控基础上进行人工打顶(简称DPC+MT)为对照.[结果]2012和201 3年花铃期(7-8月份)多雨,应用DPC化学封顶技术的棉株较高、新生果枝数较多,其中株高较DPC+MT增加10.6-12.3 cm,果枝数增加5.8-7.9台.2014年花铃期干旱少雨,DPC化学封顶的株高与DPC+MT相比无显著差异,新生果枝数不超过3台.DPC化学封顶对棉花产量的影响不显著,但可发现2012年DPC+DPC+的产量表现出降低趋势,且上部果枝成铃少、新生果枝成铃多,群体熟期有推迟现象.2013和2014年DPC+DPC+的产量和熟期则与对照相当或略有增减.DPC+的应用时间(7月中旬至7月底)和剂量(750-1 500 mL.hm-2)对棉花株型及产量的影响无显著差异,但应避免在结铃盛期(7月底)应用大剂量DPC+(1 500 mL·hm-2),以防延长后期棉铃的成熟.与DPC+DPC+相比,单独应用常规DPC化控技术进行化学封顶在多雨年份或高密度下对棉株的控长强度较弱,而且存在减产风险.[结论]应用DPC进行化学封顶在黄河流域北部棉区基本可行,实际应用时需要根据气象因子和种植密度决定单独应用常规DPC化控技术还是将常规DPC化控技术与增效型DPC的应用相结合.
DOI:10.3969/j.issn.1002-7807.2011.04.007URL [本文引用: 3]
以陆地棉品种中棉所49号为材料,于2008-2010年在新疆阿克苏市开展了化学打顶和人工打顶的田间对比试验,研究了2种打顶方式下棉花农艺性状、冠层特征、棉铃空间分布、产量性状及纤维品质的异同点。结果表明,化学打顶后棉株高于人工打顶,但株宽、果枝长及叶枝长显著低于人工打顶,因而株型更紧凑、见絮期冠层透光性好。化学打顶棉花上部果枝结铃数和内围铃数略高于人工打顶,铃重与人工打顶的相当,衣分略有降低,子棉和皮棉产量与人工打顶相当且有增产潜力,对综合纤维品质无显著影响。
DOI:10.3969/j.issn.1002-7807.2011.04.007URL [本文引用: 3]
以陆地棉品种中棉所49号为材料,于2008-2010年在新疆阿克苏市开展了化学打顶和人工打顶的田间对比试验,研究了2种打顶方式下棉花农艺性状、冠层特征、棉铃空间分布、产量性状及纤维品质的异同点。结果表明,化学打顶后棉株高于人工打顶,但株宽、果枝长及叶枝长显著低于人工打顶,因而株型更紧凑、见絮期冠层透光性好。化学打顶棉花上部果枝结铃数和内围铃数略高于人工打顶,铃重与人工打顶的相当,衣分略有降低,子棉和皮棉产量与人工打顶相当且有增产潜力,对综合纤维品质无显著影响。
DOI:10.3969/j.issn.1002-7807.2011.05.003URL [本文引用: 3]
以常规人工打顶为对照,在大田条件下设置不同种植密度(18万、 22.5万和27万株·hm-2),研究化学打顶对棉株形态、群体器官数量和经济产量等的影响.结果表明,化学打顶棉花株高显著高于人工打顶,平均高出 17％,中上部果枝显著变短,尤其是上部果枝平均比人工打顶短75％.冠层中部透光率平均提高约13％.在相同密度条件下,化学打顶棉花单位面积果枝数、 主茎节间数多于对照.化学打顶棉花的皮棉产量在密度为18万株·hm-2时为2541 kg·hm-2,与人工打顶相当；当密度增加到22.5万株·hm-2时,化学打顶的产量仍维持在较高水平(2600 kg·hm-2),而人工打顶较化学打顶产量下降了10％.因此,化学打顶的最适密度范围扩大,为进一步增密增产提供了可能.化学打顶对综合纤维品质无显 著影响.
DOI:10.3969/j.issn.1002-7807.2011.05.003URL [本文引用: 3]
以常规人工打顶为对照,在大田条件下设置不同种植密度(18万、 22.5万和27万株·hm-2),研究化学打顶对棉株形态、群体器官数量和经济产量等的影响.结果表明,化学打顶棉花株高显著高于人工打顶,平均高出 17％,中上部果枝显著变短,尤其是上部果枝平均比人工打顶短75％.冠层中部透光率平均提高约13％.在相同密度条件下,化学打顶棉花单位面积果枝数、 主茎节间数多于对照.化学打顶棉花的皮棉产量在密度为18万株·hm-2时为2541 kg·hm-2,与人工打顶相当；当密度增加到22.5万株·hm-2时,化学打顶的产量仍维持在较高水平(2600 kg·hm-2),而人工打顶较化学打顶产量下降了10％.因此,化学打顶的最适密度范围扩大,为进一步增密增产提供了可能.化学打顶对综合纤维品质无显 著影响.
DOI:10.3969/j.issn.1002-6193.2011.12.008URL [本文引用: 1]
正一、试验目的为了不断研究、开发棉花生产新技术,充分挖掘棉花生产节本增效潜力,将目前常规人工摘除顶尖和群尖的方法,改为化学整枝剂抑制生长点的生长,采用一次喷药全面整枝的化学整枝技术,最大限度简化棉田整枝工序,达到降低植棉成本的目的。
DOI:10.3969/j.issn.1002-6193.2011.12.008URL [本文引用: 1]
正一、试验目的为了不断研究、开发棉花生产新技术,充分挖掘棉花生产节本增效潜力,将目前常规人工摘除顶尖和群尖的方法,改为化学整枝剂抑制生长点的生长,采用一次喷药全面整枝的化学整枝技术,最大限度简化棉田整枝工序,达到降低植棉成本的目的。
DOI:10.3969/j.issn.1002-381X.2013.05.016URL
正打顶整枝是棉花生产中的一项 重要工作。长期以来,新疆棉区一直采用传统的人工打顶方法,近几年由于劳动力资源紧缺、用工成本过快上涨,造成打顶工作不能如期完成、打顶质量不能得到有 效保证,严重制约了棉花生产全程机械化的实现。为了解决这一难题,2008～2012年,新疆生产建设兵团第六师农业技术推广中心引进棉花化学打顶剂进行 试验研究,取得了可喜成果。试验结果表明:新疆金棉科技有限责任公司生产提供的棉花化学整枝剂应用效果良好,喷药后7～10天株高停止增长,10～15天 后棉株生长点
DOI:10.3969/j.issn.1002-381X.2013.05.016URL
正打顶整枝是棉花生产中的一项 重要工作。长期以来,新疆棉区一直采用传统的人工打顶方法,近几年由于劳动力资源紧缺、用工成本过快上涨,造成打顶工作不能如期完成、打顶质量不能得到有 效保证,严重制约了棉花生产全程机械化的实现。为了解决这一难题,2008～2012年,新疆生产建设兵团第六师农业技术推广中心引进棉花化学打顶剂进行 试验研究,取得了可喜成果。试验结果表明:新疆金棉科技有限责任公司生产提供的棉花化学整枝剂应用效果良好,喷药后7～10天株高停止增长,10～15天 后棉株生长点
DOI:10.3969/j.issn.2095-3143.2015.03.010URL [本文引用: 1]
通过调查棉花化学打顶技术在新疆玛纳斯县的应用推广现状，分析其经济效益。结果表明：棉花化学打顶技术比人工打顶技术成本指标值差异大，所产生的个体效益明显，整体效益差别显著；在产量方面化学打顶对比人工打顶略微的增长；棉花化学打顶技术大量节约了人工成本、劳动时间，对新疆棉花产业有巨大的推动作用，期待政府部门参与推广。
DOI:10.3969/j.issn.2095-3143.2015.03.010URL [本文引用: 1]
通过调查棉花化学打顶技术在新疆玛纳斯县的应用推广现状，分析其经济效益。结果表明：棉花化学打顶技术比人工打顶技术成本指标值差异大，所产生的个体效益明显，整体效益差别显著；在产量方面化学打顶对比人工打顶略微的增长；棉花化学打顶技术大量节约了人工成本、劳动时间，对新疆棉花产业有巨大的推动作用，期待政府部门参与推广。
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DOI:10.1081/PLN-100104973URL [本文引用: 1]
Nitrogen (N) nutrition greatly affects the number of nodes above the uppermost white flower (NAWF), an indicator of plant growth and development in cotton (Gossypium hirsutum L). In this study, we examined relationships of NAWF with canopy photosynthesis (CP), specific leaf weight (SLW), and yield components, boll number, and dry weight in cotton under varying N supply. Four pre-plant soil incorporated fertilizer N treatments were imposed on long-term N fertilizer plots (fine-silty, mixed, thermic Typic Fragiudalt); 0, 55, 82, and 110 kg N ha611. Soil N level had a dramatic effect on NAWF, CP, SLW, and yield components, all of which increased with increasing soil N level. However, CP and NAWF declined as the season progressed under all four soil N levels. Canopy photosynthesis, SLW, and yield components were closely associated with NAWF as the soil N increased from 0 to 110 kg N ha611. Also, the photosynthetic capacity of the canopy was strongly related to SLW under increasing soil N. These relationships of NAWF with CP, SLW, and yield components suggested that NAWF could be used as an index to predict the yield potential of cotton plants in a given environment.
URL [本文引用: 1]
ABSTRACT INTERPRETIVE SUMMARY Enhancing earliness without sacrificing yield has been a goal in cotton research programs since the early 1900s. Typically, crop maturity has been evaluated by sequentially harvesting seedcotton and comparing yields at each harvest with final yield. The most commonly used of these maturity measurements are percentage of crop harvested in the first of two harvests (% first pick) and mean maturity date. The % first pick measurement cannot be used to compare maturity among tests. Also, differences in maturity are lessened and become more obscure as the first of two harvests is delayed. Requiring multiple harvests, mean maturity date becomes more precise as the number of harvests increases. Because these measurements are based on harvest data, they cannot be used for in-season management and are easily skewed by factors that either cause premature boll opening (e.g., Verticillium wilt) or prevent boll opening (e.g., cool temperatures). As a cotton plant matures, the addition of nodes in the plant apex slows, then ceases, due to the increased assimilate demand for fruit development. Consequently, first-position white flowers occur progressively closer to the plant apex until flowering ceases. Physiological cutout (cessation of effective flowering) has been determined to occur when nodes above white flower is equal to 5.0. Sequential monitoring of nodes above white flower can be used to determine the number of days from planting until nodes above white flower = 5.0 (physiological cutout date). The objective of this research was to evaluate physiological cutout date as a measure of maturity by comparing it with harvest-based maturity measurements. We used data from three different field tests in which nodes above white flower counts and multiple harvests were available to compare the maturity measurements. Generally, measurements of physiological cutout date were closely related to harvest-based measurements. Exceptions occurred when mean values of % first pick exceeded 90% and when Verticillium wilt caused premature boll opening. Data indicate that the physiological cutout date provides a measure of crop maturity that is not confounded by boll opening conditions nor by timing of harvests. Relative maturity of cotton over time (different years) and space (different fields and tests) can be compared with physiological cutout date, because the latter is expressed in standard units of days from planting. Also, because physiological cutout date is determined during the season, it provides a convenient and timely measure of crop maturity.
URL [本文引用: 1]
ＮＡＷＦ在美国棉花生产上的应用①ＡＰＰｌｉｃａｔｉｏｎＮＡＷＦｉｎｃｏｔｏｎｐｒｏｄｕｃｔｉｏｎｉｎＵＳＡＮＡＷＦ（ＮｏｄｅｓＡｂｏｖｅＷｈｉｔｅＦｌｏｗｅｒ），或称ＮＡＷＢ（ＮｏｄｅｓＡｂｏｖｅＷｈｉｔｅＢｌｏｏｍ），指在棉株几何空间上近主茎顶端而...
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ＮＡＷＦ在美国棉花生产上的应用①ＡＰＰｌｉｃａｔｉｏｎＮＡＷＦｉｎｃｏｔｏｎｐｒｏｄｕｃｔｉｏｎｉｎＵＳＡＮＡＷＦ（ＮｏｄｅｓＡｂｏｖｅＷｈｉｔｅＦｌｏｗｅｒ），或称ＮＡＷＢ（ＮｏｄｅｓＡｂｏｖｅＷｈｉｔｅＢｌｏｏｍ），指在棉株几何空间上近主茎顶端而...
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DOI:10.3969/j.issn.1002-7807.2012.05.006URL [本文引用: 2]
利用生物信息学结合RT- PCR技术从陆地棉中克隆出SPL转录因子,命名为GhSPL3,在GenBank的登录号为JN795132。该基因包含一个426 bp的ORF(开放阅读框),推测编码141个氨基酸的多肽。生物信息学分析表明GhSPL3包含一个典型的SBP结构域和一个核定位信号;进化树分析发 现,GhSPL3与AtSPL3聚为一组,推测棉花GhSPL3和拟南芥AtSPL3在结构和功能上可能有着一定的相似性。亚细胞定位表明,GhSPL3 定位于细胞核中,荧光定量RT-PCR结果表明,GhSPL3基因在棉花各组织中都有表达,但表达量不同。在花中表达量最高,其次是在顶芽和茎中的表达 量,在根和叶中表达量较低。通过分析GhSPL3在顶芽的不同发育时期的表达量发现,GhSPL3在三片真叶展平时的顶芽中表达量最高,推测GhSPL3 可能在花芽的分化、生长阶段的转变和花器官的形成上起着重要作用。
DOI:10.3969/j.issn.1002-7807.2012.05.006URL [本文引用: 2]
利用生物信息学结合RT- PCR技术从陆地棉中克隆出SPL转录因子,命名为GhSPL3,在GenBank的登录号为JN795132。该基因包含一个426 bp的ORF(开放阅读框),推测编码141个氨基酸的多肽。生物信息学分析表明GhSPL3包含一个典型的SBP结构域和一个核定位信号;进化树分析发 现,GhSPL3与AtSPL3聚为一组,推测棉花GhSPL3和拟南芥AtSPL3在结构和功能上可能有着一定的相似性。亚细胞定位表明,GhSPL3 定位于细胞核中,荧光定量RT-PCR结果表明,GhSPL3基因在棉花各组织中都有表达,但表达量不同。在花中表达量最高,其次是在顶芽和茎中的表达 量,在根和叶中表达量较低。通过分析GhSPL3在顶芽的不同发育时期的表达量发现,GhSPL3在三片真叶展平时的顶芽中表达量最高,推测GhSPL3 可能在花芽的分化、生长阶段的转变和花器官的形成上起着重要作用。
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DOI:10.1093/jxb/erv174URLPMID:25911742 [本文引用: 1]
The homeodomain-leucine zipper (HD-Zip) class of transcription factors is unique to plants. HD-Zip proteins bind to DNA exclusively as dimers recognizing dyad symmetric sequences and act as positive or negative regulators of gene expression. On the basis of sequence homology in the HD-Zip DNA-binding domain, HD-Zip proteins have been grouped into four families (HD-Zip I-IV). Each HD-Zip family can be further divided into subfamilies containing paralogous genes that have arisen through genome duplication. Remarkably, all the members of the HD-Zip IIγ and -δ clades are regulated by light quality changes that induce in the majority of the angiosperms the shade-avoidance response, a process regulated at multiple levels by auxin. Intriguingly, it has recently emerged that, apart from their function in shade avoidance, the HD-Zip IIγ and -δ transcription factors control several auxin-regulated developmental processes, including apical embryo patterning, lateral organ polarity, and gynoecium development, in a white-light environment. This review presents recent advances in our understanding of HD-Zip II protein function in plant development, with particular emphasis on the impact of loss-of-function HD-Zip II mutations on auxin distribution and response. The review also describes evidence demonstrating that HD-Zip IIγ and -δ genes are directly and positively regulated by HD-Zip III transcription factors, primary determinants of apical shoot development, known to control the expression of several auxin biosynthesis, transport, and response genes. Finally, the interplay between HD-Zip II and III transcription factors in embryo apical patterning and organ polarity is discussed.
DOI:10.1101/gad.9.18.2314URLPMID:7555701 [本文引用: 1]
Abstract The form of seed plants is determined by the growth of a number of meristems including apical meristems, leaf meristems and cambium layers. We investigated five recessive mutant alleles of a gene REVOLUTA that is required to promote the growth of apical meristems and to limit cell division in leaves and stems of Arabidopsis thaliana. REVOLUTA maps to the bottom of the fifth chromosome. Apical meristems of both paraclades (axillary shoots) and flowers of revoluta mutants frequently fail to complete normal development and form incomplete or abortive structures. The primary shoot apical meristem sometimes also arrests development early. Leaves, stems and floral organs, in contrast, grow abnormally large. We show that in the leaf epidermis this extra growth is due to extra cell divisions in the leaf basal meristem. The extent of leaf growth is negatively correlated with the development of a paraclade in the leaf axil. The thickened stems contain extra cell layers, arranged in rings, indicating that they may result from a cambium-like meristem. These results suggest that the REVOLUTA gene has a role in regulating the relative growth of apical and non-apical meristems in Arabidopsis.
DOI:10.1371/journal.pgen.1006168URLPMID:27398935 [本文引用: 1]
Shoot branching requires the establishment of new meristems harboring stem cells; this phenomenon raises questions about the precise regulation of meristematic fate. In seed plants, these new meristems initiate in leaf axils to enable lateral shoot branching. Using live-cell imaging of leaf axil cells, we show that the initiation of axillary meristems requires a meristematic cell population continuously expressing the meristem markerSHOOT MERISTEMLESS(STM). The maintenance ofSTMexpression depends on the leaf axil auxin minimum. Ectopic expression ofSTMis insufficient to activate axillary buds formation from plants that have lost leaf axilSTMexpressing cells. This suggests that some cells undergo irreversible commitment to a developmental fate. In more mature leaves,REVOLUTA(REV) directly up-regulatesSTMexpression in leaf axil meristematic cells, but not in differentiated cells, to establish axillary meristems. Cell type-specific binding of REV to theSTMregion correlates with epigenetic modifications. Our data favor a threshold model for axillary meristem initiation, in which low levels ofSTMmaintain meristematic competence and high levels ofSTMlead to meristem initiation. In seed plants, branches arise from axillary meristems (AMs), which form in the crook between the leaf and the stem. How AMs initiate to produce branches remains unclear. In this study, we show that a group of meristematic cells maintain expression of the meristem markerSHOOT MERISTEMLESS(STM); the progeny of these cells form the axillary buds. Our results suggest that low-levelSTMexpression is required (but not sufficient) for AM initiation, and that high-levelSTMexpression induces initiation of the AM. The initial expression ofSTMrequires the auxin minimum in the leaf axil and the transcription factor REVOLUTA directly up-regulatesSTMexpression.
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DOI:10.1016/j.plaphy.2010.08.016URLPMID:20870416 [本文引用: 1]
Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The ROS comprises both free radical (O , hydrogen peroxide and O, singlet oxygen). In chloroplasts, photosystem I and II (PSI and PSII) are the major sites for the production of O and O - transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and -tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.Research highlights? Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates, DNA which ultimately results in oxidative stress. ? The antioxidant defense machinery protects plants against oxidative stress damages. ? Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and -tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ? ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.
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活性氧(reactive oxygen species,ROS)是植物有氧代谢的副产物,同时环境胁迫也会使植物细胞中积累大量的活性氧.低浓度的活性氧可以作为信号分子存在,诱导防御基因的 表达和植物对环境的适应反应.当逆境胁迫迫使植物细胞中产生大量活性氧时,就会导致细胞内的大分子物质及其他组分受损,阻碍植物的正常代谢和生长,甚至死 亡.植物体内存在活性氧清除机制,可以在一定范围内维持活性氧的平衡.研究表明,利用植物体内自身的活性氧清除机制可以提高植物的抗逆性.对当前植物活性 氧的研究动态进行概述,同时对植物活性氧清除机制在提高植物抗逆性方面的应用进行探讨.
URL [本文引用: 1]
活性氧(reactive oxygen species,ROS)是植物有氧代谢的副产物,同时环境胁迫也会使植物细胞中积累大量的活性氧.低浓度的活性氧可以作为信号分子存在,诱导防御基因的 表达和植物对环境的适应反应.当逆境胁迫迫使植物细胞中产生大量活性氧时,就会导致细胞内的大分子物质及其他组分受损,阻碍植物的正常代谢和生长,甚至死 亡.植物体内存在活性氧清除机制,可以在一定范围内维持活性氧的平衡.研究表明,利用植物体内自身的活性氧清除机制可以提高植物的抗逆性.对当前植物活性 氧的研究动态进行概述,同时对植物活性氧清除机制在提高植物抗逆性方面的应用进行探讨.
DOI:10.1007/s00438-014-0901-xURLPMID:25159110 [本文引用: 1]
SQUAMOSA promoter binding protein - like ( SPL ) genes encode plant-specific transcription factors that are involved in many fundamental developmental processes. Certain SPL genes contain sequences complementary to miR156, a microRNA (miRNA) that plays a role in modulating plant gene expression. In this study, 30 SPL genes were identified in the reference genome of Gossypium raimondii and 24 GhSPLs were cloned from Gossypium hirsutum . G. raimondii is regarded as the putative contributor of the D-subgenome of G. hirsutum . Comparative analysis demonstrated sequence conservation between GhSPLs and other plant species. GhSPL genes could be classified into seven subclades based on phylogenetic analysis, diverse intron鈥揺xon structure, and motif prediction. Within each subclade, genes shared a similar structure. Sequence and experimental analysis predicted that 18 GhSPL genes are putative targets of GhmiR156. Additionally, tissue-specific expression analysis of GhSPL genes showed that their spatiotemporal expression patterns during development progressed differently, with most genes having high transcript levels in leaves, stems, and flowers. Finally, overexpression of GhSPL3 and GhSPL18 in Arabidopsis plants demonstrated that these two genes are involved in the development of leaves and second shoots and play an integral role in promoting flowering. The flowering integrator GhSOC1 may bind to the promoter of GhSPL3 but not GhSPL18 to regulate flowering. In conclusion, our analysis of GhSPL genes will provide some gene resources and a further understanding of GhSPL3 and GhSPL18 function in flowering promotion. Furthermore, the comparative genomics and functional analysis deepened our understanding of GhSPL genes during upland cotton vegetative and reproductive growth.
DOI:10.1080/10425170600824335URLPMID:17343206 [本文引用: 1]
Class III homeodomain-leucine zipper (-Zip III) genes are important plant-specific factors which have key roles in different stages of vascular and interfascicular fiber differentiation. A novel -Zip III gene, designated GbHB1, was isolated by suppression subtraction hybridization and (rapid amplification of cDNA ends) from (). The GbHB1 cDNA has a total length of 3061 bp with an open reading frame of 2508 bp, encoding a predicated of 836 amino acids with a molecular weight of 91.6 kDa and a calculated pI of 5.93. The putative of GbHB1 is structurally characterized by a homeodomain positioned adjacent to a leucine zipper domain, which shares high identity with other reported -Zip III domains. DNA gel blotting analysis shows that GbHB1 is a low-copy gene. Organ expression pattern analysis reveals that GbHB1 expressed highly in ovule and stem, followed by in root, and low in leaf and . The result suggests that GbHB1 may play a regulatory role in interfascicular fiber .
DOI:10.7606/j.issn.1004-1389.2015.08.011URL [本文引用: 1]
To discuss the main acting part and effect of chemical capping agent in cotton,so as to improve the efficiency of chemical caping and to tap potential of high yield. Conventional decapitation topping as CK.By marking on the upper part of the stem, leaves and branches before the test, we used different dose of chemical topping agent to study effect of chemical topping on morphologic changes of leaves and branches in upper part of cotton morphologic changes.The results showed that plant height of cotton treated by chemical agent topping was 5 cm higher than that of one treated by artificial topping.but the more dose of chemical agent used, the more obvious the inhibition had. The chemical topping agent mainly functioned in inhibiting upper internode elongation, but it maybe could promote the lower internode elongation.The diameter of upper stem got smaller, branch length got shoter, leaf width got narrow, the value was on the trend of increase,it was more conducive to ventilation and photosynthesis.The cotton boll numbers increased and the growth rate accelerated, but the rate of boll-setting was low at end period of growth.The analysis showed that chemical topping agent affected foliage morphology in the upper part of cotton, so the plants were compact, boll increased, but had little influence on cotton bolling.
DOI:10.7606/j.issn.1004-1389.2015.08.011URL [本文引用: 1]
To discuss the main acting part and effect of chemical capping agent in cotton,so as to improve the efficiency of chemical caping and to tap potential of high yield. Conventional decapitation topping as CK.By marking on the upper part of the stem, leaves and branches before the test, we used different dose of chemical topping agent to study effect of chemical topping on morphologic changes of leaves and branches in upper part of cotton morphologic changes.The results showed that plant height of cotton treated by chemical agent topping was 5 cm higher than that of one treated by artificial topping.but the more dose of chemical agent used, the more obvious the inhibition had. The chemical topping agent mainly functioned in inhibiting upper internode elongation, but it maybe could promote the lower internode elongation.The diameter of upper stem got smaller, branch length got shoter, leaf width got narrow, the value was on the trend of increase,it was more conducive to ventilation and photosynthesis.The cotton boll numbers increased and the growth rate accelerated, but the rate of boll-setting was low at end period of growth.The analysis showed that chemical topping agent affected foliage morphology in the upper part of cotton, so the plants were compact, boll increased, but had little influence on cotton bolling.
DOI:10.3864/j.issn.0578-1752.2016.09.004URL [本文引用: 1]
【目的】选用氟节胺复配型、缩节胺复配型2种化学打顶剂,研究田间喷施化学打顶剂对棉花株型特征、冠层结构、群体光合生产及产量的影响,分析冠层结构变化对群体光合生产和产量的影响,为棉花化学打顶技术的应用提供理论依据。【方法】选用北疆棉区主栽品种(新陆早45号)和主推品种(系)(中棉所50、45-21)为试验材料,在田间自然条件下,以常规人工打顶的棉花为对照,分别测定不同棉花品种(系)株高、株宽、叶面积指数、叶片叶绿素含量、冠层不同部位透光率、群体光合速率及产量构成等指标。研究化学打顶技术对棉花叶面积指数、冠层透光率、群体光合速率及产量的影响。【结果】与人工打顶的棉花相比,化学打顶的棉花株高显著高于人工打顶处理,且喷药后生长量较大;株宽显著小于人工打顶处理,喷药后横向生长被明显抑制。化学打顶的棉花叶面积指数和叶片叶绿素含量较高,且高值持续期长,至初絮期(出苗后115 d)仍维持较高的值,与人工打顶的棉花相比差异均达到极显著水平;冠层上、中部透光率较高,生育后期冠层下部漏光损失较小。化学打顶的棉花群体光合速率显著高于人工打顶,且高值持续期长,至初絮期仍维持在16.04μmol·m~(-2)·s~(-1)以上,较人工打顶的棉花高出14.35%—36.35%,差异均达到显著水平;群体呼吸速率在达到峰值前显著高于人工打顶的棉花,峰值后与人工打顶的棉花无显著差异;群体呼吸速率占群体总光合速率的比率高于人工打顶的棉花。化学打顶的棉花单株结铃多,其中氟节胺处理棉花产量高于人工打顶。【结论】棉花化学打顶技术具有塑造株型、调节棉花冠层结构形成的重要作用;同时棉花冠层上、中部透光率大,改善了冠层中下部光环境,保证了冠层各部位均匀的光分布。化学打顶的棉花叶面积指数高且高值持续期长,增加了光合面积。叶片叶绿素含量高且高值持续时间长,延长了光合时间,保证了较高的群体光合能力及长的光合功能持续期。
DOI:10.3864/j.issn.0578-1752.2016.09.004URL [本文引用: 1]
【目的】选用氟节胺复配型、缩节胺复配型2种化学打顶剂,研究田间喷施化学打顶剂对棉花株型特征、冠层结构、群体光合生产及产量的影响,分析冠层结构变化对群体光合生产和产量的影响,为棉花化学打顶技术的应用提供理论依据。【方法】选用北疆棉区主栽品种(新陆早45号)和主推品种(系)(中棉所50、45-21)为试验材料,在田间自然条件下,以常规人工打顶的棉花为对照,分别测定不同棉花品种(系)株高、株宽、叶面积指数、叶片叶绿素含量、冠层不同部位透光率、群体光合速率及产量构成等指标。研究化学打顶技术对棉花叶面积指数、冠层透光率、群体光合速率及产量的影响。【结果】与人工打顶的棉花相比,化学打顶的棉花株高显著高于人工打顶处理,且喷药后生长量较大;株宽显著小于人工打顶处理,喷药后横向生长被明显抑制。化学打顶的棉花叶面积指数和叶片叶绿素含量较高,且高值持续期长,至初絮期(出苗后115 d)仍维持较高的值,与人工打顶的棉花相比差异均达到极显著水平;冠层上、中部透光率较高,生育后期冠层下部漏光损失较小。化学打顶的棉花群体光合速率显著高于人工打顶,且高值持续期长,至初絮期仍维持在16.04μmol·m~(-2)·s~(-1)以上,较人工打顶的棉花高出14.35%—36.35%,差异均达到显著水平;群体呼吸速率在达到峰值前显著高于人工打顶的棉花,峰值后与人工打顶的棉花无显著差异;群体呼吸速率占群体总光合速率的比率高于人工打顶的棉花。化学打顶的棉花单株结铃多,其中氟节胺处理棉花产量高于人工打顶。【结论】棉花化学打顶技术具有塑造株型、调节棉花冠层结构形成的重要作用;同时棉花冠层上、中部透光率大,改善了冠层中下部光环境,保证了冠层各部位均匀的光分布。化学打顶的棉花叶面积指数高且高值持续期长,增加了光合面积。叶片叶绿素含量高且高值持续时间长,延长了光合时间,保证了较高的群体光合能力及长的光合功能持续期。
