,1,2, 李波2, 陈喜昌2, 丁在松1, 张宇2, 赵明,1, 李从锋,1Regulation Effects of Improved Cultivation Measures on Canopy Structure and Yield Formation of Dense Spring Maize Population
PIAO Lin,1,2, LI Bo2, CHEN XiChang2, DING ZaiSong1, ZHANG Yu2, ZHAO Ming,1, LI CongFeng,1通讯作者:
责任编辑: 杨鑫浩
收稿日期:2020-04-21接受日期:2020-06-15网络出版日期:2020-08-01
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Received:2020-04-21Accepted:2020-06-15Online:2020-08-01
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朴琳, 李波, 陈喜昌, 丁在松, 张宇, 赵明, 李从锋. 优化栽培措施对春玉米密植群体冠层结构及产量形成的调控效应[J]. 中国农业科学, 2020, 53(15): 3048-3058 doi:10.3864/j.issn.0578-1752.2020.15.006
PIAO Lin, LI Bo, CHEN XiChang, DING ZaiSong, ZHANG Yu, ZHAO Ming, LI CongFeng.
0 引言
【研究意义】现今我国玉米籽粒产量的提升,主要归因于合理种植模式下群体密度和花后干物质的不断增加[1,2,3]。通过改良关键栽培措施,改善玉米群体物质的空间分布,实现春玉米花后物质生产与积累的提升,在东北春玉米高产挖潜研究中得到证实[4,5]。但是多个栽培措施协同作用下高产玉米群体的冠层结构特征,及其增产机制却鲜见报道。进一步的高产挖潜必然依赖于合理综合栽培模式,深入解析多措施模式下冠层结构功能特征对产量形成的贡献,对完善春玉米田间冠层表型理论和高产高效优化栽培模式构建都具有重要意义。【前人研究进展】灌浆期叶片合成的光合产物,及其输出与分配直接决定了产量形成的物质基础[6,7]。玉米籽粒产量几乎全部来源于吐丝后的光合产物,因此该生育阶段冠层叶片的光合性能直接决定了籽粒产量的形成[8,9,10]。在较高种植密度下,群体内的拥挤胁迫加剧了植株间的竞争[11],由于光照[12]、养分和水分资源的不足,群体冠层中下部叶片往往出现早衰[8],灌浆期叶片的光合速率及根系活力下降显著[3],限制籽粒物质积累,产量降低[11, 13]。深松耕作、宽窄行种植、叶面喷施化控调节剂是目前东北地区高密种植中行之有效的优化栽培技术[14,15]。实践表明,宽窄行的疏密种植方式,灌浆期叶片（尤其是冠层中下部）的净光合速率显著提高,籽粒活跃灌浆期延长,更多的花后干物质生产,并分配积累到籽粒[16,17]。与传统等行距不同,宽窄行种植下冠层干物质的权重下移明显,冠层垂直分布更加均匀,更有益于下部叶片光能截获及功能期维持,粒重显著提高,实现增产[18]。深松可以打破犁底层及夯实土层疏松土壤,促进根系的生长发育,根长显著增加,水分及养分的吸收显著提高,有利于花后冠层的物质积累[17, 19]。拔节期200 mg·kg-1乙矮合剂（Ethylene-CCC-PASPK;ECK）处理,穗下节间缩短,穗上节间增长,群体下层透光率增加显著[20]。水分及养分的吸收与利用取决于根系的生长与发育,耕层通过对根系生长的影响间接作用于冠层物质的生产与积累[21],从而实现产量的提高[22]。东北地区耕层土壤通透性差,严重制约了产量的提升[23]。深松可以改善土壤的通透性[24],延迟花后叶片衰老,产量增加显著[25,26,27]。【本研究切入点】现有研究多是单项关键技术的调控效应,关于集成多个关键技术是否可以实现产量的进一步提升,及其增产机制尚缺乏系统研究。本研究以春玉米密植群体的冠层结构为切入点,通过组配不同关键栽培技术,设置不同冠层和耕层优化模式,并提出科学假设：协同优化春玉米密植群体的耕层与冠层结构,可改善因密度增加导致的拥挤胁迫,调节叶片的光合生产能力,延长活跃灌浆期,增加籽粒干物质的积累,实现产量的进一步提升。【拟解决的关键问题】本研究于2013和2014年基于不同优化栽培措施,明确春玉米高产高效密植冠层的结构特征,解析密植群体冠层结构特性、叶片功能性及其与产量形成的关系,为东北春玉米资源高效栽培模式的构建提供理论依据和技术支持。1 材料与方法
1.1 试验设计
试验分别于2013和2014年在辽宁省铁岭县张庄合作社中国农科院试验基地进行,试验田为棕壤土,含有机质19.6 g·kg-1,全氮1.12 g·kg-1,有效氮132.8 mg·kg-1,速效磷33.26 mg·kg-1,速效钾161.57 mg·kg-1。1992—2014年生长季（5—10月）日均气温 21℃左右,常年日照3 000—3 200 h,2013年玉米生长季降水745 mm（多雨）,而2014年生长季降水497 mm（少雨）。以耐密品种中单909为试材,种植密度为105 000株/hm2,设置4种根-冠优化栽培模式：（1）常规栽培模式（旋耕20 cm,60 cm等行距,RU）,（2）耕层优化模式（深松耕作35 cm,60 cm等行距,SU）,（3）冠层优化模式（传统旋耕20 cm,80 cm+40 cm宽窄行,6展叶人工均匀叶面喷施浓度为200 mg·kg-1的磷酸胆碱合剂ECK（“金得乐”加强型）,225 kg·hm-2,RWC）,（4）综合优化模式（深松耕作35 cm,80 cm+40 cm宽窄行,6展叶人工均匀叶面喷施浓度为200 mg·kg-1的磷酸胆碱合剂ECK（“金得乐”加强型）225 kg·hm-2,SWC）。播种前机械一次性侧深施入“愚公”牌长效复合肥（N:P2O5:K2O=12:18:15）75 kg·hm-2,以及控释掺混肥（N:P2O5:K2O=27:11:12） 750 kg·hm-2（纯N 315.75 kg·hm-2;147.38 kg·hm-2 P2O5;236.25 kg·hm-2 K2O）。小区面积48.72 m2（6 m× 8.4 m）,3次重复。第1年试验于2013年5月12日播种,2013年10月3日收获,第2年试验2014年4月26日播种,2014年10月4日收获,其他田间管理措施同当地玉米高产田。1.2 测定项目及方法
1.2.1 干物质积累 在田间选取长势一致的3株样本进行干物质积累测定,2013年分别在玉米V3（3展叶）、V8（8展叶）、V12（12展叶）、R1（开花）、R3（灌浆）及R6期（收获）取样,2014年分别在V8（8展叶）、V12（12展叶）、R1（开花）、R3（灌浆）及R6期（收获）取样,3次重复;采用Logistic方程（Y=a（1+be-ct）-1）进行数据拟合,得到干物质活跃积累期等特征参数。1.2.2 大田切片法 在玉米灌浆期（R1）各处理选取长势一致2 m2区域为样本,采用截枝钳以30 cm为一层,从地表起到植株顶端分层割取样本,样本叶片和茎秆分开保存,105℃杀青30 min,恒温75℃烘干至恒重,分别称重计算干物质积累量。
1.2.3 光合参数测定 选择美国LI-COR便携式LI-6400光合测定系统,于2013年花后5 d和2014花后10 d的晴朗天气10：00—14：00,对各处理长势一致的3株玉米进行光合参数测定。田间测定采用内置光源,自然光下光强设为2 000 photons μmol·m-2·s-1,测定果穗叶片中部的净光合速率（Pn）变化。
1.2.4 光分布测定 利用自制带有10个光量子探头的钢架置于田间植株间,从地面到冠层顶部每隔30 cm分为一层,在玉米灌浆期实时记录不同处理冠层的光辐射强度数值（对宽窄行种植处理,于宽行和窄行分别测定取均值）。
1.2.5 SPAD值测定 利用SPAD-502型叶绿素计,选取每个处理代表性植株5株,选择植株穗位叶叶片中部,且距离叶脉相同距离位置,进行SPAD值的测定。
1.2.6 蔗糖磷酸合成酶（SPS）和蔗糖合成酶（SS）活性测定 称取玉米叶片的中间部分0.5 g左右,放置冷冻后的研钵内进行人工研磨,Hepes-NaOH缓冲提取液3 mL研磨至匀浆,在12 000 r/min 4℃下离心15 min取上清液,参照MIRON等[28]的方法测定获得酶活性。
1.2.7 籽粒灌浆特征观察 从玉米花后15 d以后,每隔7 d左右,每个处理选取3个典型果穗从中间掰开,剥取果穗中下部籽粒100 粒,80℃烘箱烘干至恒重。
1.2.8 籽粒产量测定 在玉米生理成熟时,每个小区选取中间6行所有果穗人工收获,进行脱粒测定籽粒重,获得14%含水量下的玉米产量。
1.3 数据统计与分析
采用SAS统计软件包（SAS,ver. 9.2版,USA）和SPSS 17.0（SPSS,ver. 17.0版,USA）进行单因素方差分析,在0.05概率水平上比较差异性。2 结果
2.1 不同栽培模式下春玉米群体冠层结构
2.1.1 冠层生物量的垂直结构 由图1可知,冠层优化模式（RWC）和综合优化模式（SWC）较传统模式（RU）和耕层优化模式（SU）穗位降低30 cm,穗位分布群体内整齐度也明显下降。干物质分布随株高增加先升高后降低（穗位最高）,其中冠层优化模式穗位层（RWC和SWC;120—150 cm）干物质重量占比较传统模式（RU;150—180 cm）增加18%—19%,基部（0—90 cm除穗重部分）干物质重量占比降低20%—23%。穗位干物质重量占比的增加和基部干物质占比的减小,使群体生物量垂直分布更均匀,重心降低。图1
新窗口打开|下载原图ZIP|生成PPT图12014年不同栽培模式春玉米群体冠层生物量垂直分布
RU,传统栽培模式（CK）;SU,耕层优化模式;RWC,冠层优化模式;SWC,综合优化模式。灰色柱代表果穗所在层干物质重（及下层果穗重）,黑色和深灰色柱分别代表穗下和穗上干物重。下同
Fig. 1Vertical distribution of canopy biomass in spring maize under different cultivation modes in 2014
RU, conventional mode (CK); SU, tillage improved mode; RWC, canopy improved mode; SWC, synthetical improved mode. The gray bar represents the biomass weight of ear layers (and the ear weight in lower layer), dark gray and break bars represent the biomass weight of upper and lower ear layers respectively. The same as below
2.1.2 群体冠层的光分布 叶片生物量的垂直分布处理间表现出显著差异。相较于传统模式（RU）,深松处理（SU）冠层顶部叶片更加繁茂,这是由于改善耕层对冠层的间接作用。在化学调控剂的作用下,冠层优化模式和综合优化模式（RWC和SWC）冠层顶部（160—270 cm）叶片生物量显著低于对照处理,但中部（70—160 cm）叶片分布显著高于对照处理。冠层内光能截获率垂直分布与叶片分布趋势一致,传统等行距模式光截获主要集中在穗上叶层（180—240 cm）,耕层优化模式较传统模式明显改善了穗位以下叶层的光能分布;冠层优化栽培模式显著降低了群体穗上叶层的光能截获,更多的光能辐射被穗位及穗位以下叶层所捕获（44%—129%）（图2）。
图2
新窗口打开|下载原图ZIP|生成PPT图22014年不同栽培模式春玉米群体冠层光的垂直分布
黑色区域表示优化处理绿叶干物质重和透光率高于对照（RU）部分;灰色区域代表对照（RU）绿叶干物质重和透光率高于优化处理部分。虚线标注穗位所在高度
Fig. 2The vertical distribution of canopy transmittance under different cultivation modes in 2014
The black region (optimized treatment>control) and gray region (optimized treatment<control) indicated the difference value of treatments. Dotted line indicates the height of the ear
2.2 不同栽培模式下春玉米冠层光合生理
2.2.1 叶绿素及光合速率 叶色值（SPAD值）群体内的垂直分布处理间趋势一致,随高度的增加逐渐升高（2014,图3）,且穗位以上处理间差异不显著。RWC和SWC处理的下层叶色值高于RU处理（2014,图3）。玉米高密群体不同叶层中叶片净光合速率（Pn）群体内垂直变化与叶色值趋势一致,且穗位以上不同栽培模式间没有明显差异,穗位叶及穗下叶片净光合速率（Pn）冠层优化模式下显著高于传统模式（图3）。冠层优化模式可以提高下层叶色值和光合速率,延缓衰老,提高生产能力。图3
新窗口打开|下载原图ZIP|生成PPT图3不同栽培模式下春玉米SPAD值及净光合速率
小写字母表示0.05显著水平。下同
Fig. 3SPAD value and net photosynthetic rates (Pn) in maize at filling stage of different cultivation modes
Small letters indicate significantly different at 0.05 probability level. The same as below
2.2.2 碳代谢关键酶活性 蔗糖合成运转过程中蔗糖磷酸合酶（SPS）和蔗糖合成酶（SS）起到关键性调节作用,其活性可进一步用作衡量叶片蔗糖合成代谢能力。灌浆期功能叶片中SPS和SS活性,呈先升高再降低的变化趋势,其峰值出现在开花后30 d左右。与对照相比,不同优化栽培模式均能显著提高穗位叶SPS和SS活性,且SWC处理最高,SU和RWC处理相近,RU处理最低（图4）。
图4
新窗口打开|下载原图ZIP|生成PPT图4不同栽培模式下穗位叶蔗糖磷酸合酶（SPS）及蔗糖合成酶（SS）活性
“*”表示0.05显著水平。下同
Fig. 4Sucrose phosphate synthase (SPS), and sucrose synthetase (SS) activity of different cultivation modes
“*”represent significance at the 0.05 probability. The same as below
2.3 春玉米群体物质生产及产量形成
2.3.1 干物质积累特征 玉米单株干物质积累以根冠协同优化模式最高,传统模式最低甚至成熟期有所降低（图5）,生育前中期差异不显著。用Logistic方程拟合计算作物物质积累参数,可能是由于灌浆期出现阶段性干旱,生育期降水减少的缘故,2014年干物质活跃积累期较2013年缩短1—11 d,其中2013年优化栽培模式活跃积累期较传统模式增加4—13 d,耕层优化模式增加4 d,而冠层优化模式增加10 d以上;而2014年仅增加2—7 d。优化栽培模式显著延长了物质积累活跃期,为产量的提升奠定了物质基础[29]。图5
新窗口打开|下载原图ZIP|生成PPT图5不同栽培模式下春玉米干物质积累动态
白色柱代表缓慢增长期,黑色柱代表快速增长期,灰色柱代表增长维持期
Fig. 5Biomass accumulation under different cultivation modes on maize
The white, black and grey bars represent the period of slow, rapid and maintain respectively
2.3.2 籽粒灌浆特性 作物籽粒灌浆可分为缓慢增长、线性增长和粒重维持3个阶段,其动态可用Logistic方程拟合描述,灌浆中后期百粒重综合优化模式（SWC）>耕层优化模式（SU）≥冠层优化模式（RWC）>传统种植模式（RU）。由于2014年灌浆期出现干旱胁迫,生育期降雨量降低导致百粒日增量明显低于2013年。优化栽培模式百粒灌浆速率达到最大时日期均早于传统模式（2013年提早较多）,灌浆活跃期显著延长（2014年延长相对较长）,耕层优化模式（SU）延长较少,但冠层优化模式（RWC）和综合优化模式（SWC）的活跃灌浆期最多可延长7—12 d（图6）。
图6
新窗口打开|下载原图ZIP|生成PPT图6不同栽培模式春玉米粒重动态与灌浆速率
Fig. 6Dry grain weight per 100-kernel dynamics and filling rate under different cultivation modes
2.3.3 籽粒产量 对比不同处理籽粒产量,综合优化栽培模式（SWC）2年间产量均最高;相较于传统模式（RU）,产量增益分别为31.26%和15.02%;冠层优化模式（RWC）产量增益次之,分别为13.31%和9.17%,耕层优化模式（SU）2年间产量增益均在5%左右,群体籽粒产量受栽培模式显著调控,且耕层优化模式产量增益较冠层优化模式更为稳定,耕层和冠层优化对于籽粒产量的调控上存在明显的协同性。方差分析表明,栽培模式对产量影响显著,而年型对籽粒产量没有显著影响,年型与栽培模式对产量也没有显著的交互效应（图7）。
图7
新窗口打开|下载原图ZIP|生成PPT图7栽培模式对不同年型春玉米产量的调控
不同年型产量的方差分析：年型 Year (Y),P=0.192;栽培模式（C）,P=0.014;Y×C,P =0.496;P<0.05表示差异显著
Fig. 7The effects of cultivation modes on yield
Yield in variance analysis of different year: Year (Y), P=0.192; Cultivation mode(C), P=0.014; Y× C: P =0.496.; P<0.05 indicates significant difference
3 讨论
玉米生长发育所需的化学能,是由叶片对光能截获和光合作用转化而来的。群体生物量的垂直结构通过影响叶片的空间布局,调节了群体内叶片对自然光照辐射的捕捉。调整行株距配置,不均匀种植可显著改变群体冠层生物量的分布,调控叶片朝向及茎叶夹角,通过协调冠层中下部的光分布,改善群体内中下部叶片的受光情况[18,20,30]。本研究中,冠层优化模式综合了宽窄行距种植和化学调节剂的效果,重塑了群体冠层物质垂直结构,冠层生物量穗位层分布增加20%,进一步改善了穗下部的光环境。深松耕作可有效改变耕层结构,促进根系的伸长生长,强化深层根系对土壤中水分、养分的汲取活力,对地上干物质的生产有间接促进作用,有效改善了生育后期冠层叶片光合作用的维持,增加花后物质的积累[17, 19]。耕层优化间接作用于冠层结构,从而调控物质生产,影响产量形成,也有报道认为耕层对高产的贡献高于冠层[31]。耕层优化模式显著提高了穗下绿色叶片干重和冠层生物量积累,耕层冠层综合优化模式,冠层结构改善更加明显,但是单独的耕层优化并不能改变冠层垂直结构（图1—2）。调控玉米群体的光分布,增加中下层叶片的光能捕获,更有益于叶片光合性能的提高和功能期的维持。母体植株提供的光合同化物的增加是籽粒产量提高的重要原因[7,8]。叶片光合同化物主要以蔗糖形式运转,蔗糖磷酸合酶（sucrose phosphate synthase,SPS）和蔗糖合成酶（sucrose synthetase,SS）是蔗糖合成运转代谢的主要限速酶[32,33],其活性可作为反映叶片碳合成代谢能力的重要指标。开花到成熟期玉米群体蔗糖的生产与分配对籽粒的产量贡献显著高于花前,且此阶段的叶片光合生产效率、光合产物的运输及籽粒的卸载积累对产量挖潜都具有重要意义[34,35,36,37]。综合优化模式下,群体内光环境的改善使春玉米密植群体花后中下部叶片的叶绿素含量和净光合速率显著提高（图3）,穗位功能叶片SPS和SS酶活性显著提高（图4）,叶片的物质生产能力增加,奠定了灌浆后期干物质积累的物质基础,群体干物质的活跃积累期增加10 d以上（图5）,籽粒活跃灌浆期延长且最大灌浆速率提高（图6）。
本研究中综合模式籽粒产量最高,冠层优化模式和耕层优化模式同处中等水平,传统模式最低。综合栽培模式实现了密植群体产量的进一步提升,是未来玉米密植高产的可行性策略。冠层优化缓解了因增加密度导致的群体内拥挤胁迫,穗位层物质分布占比的增加及植株重心的降低,使群体内中下部的通风透光性得到了极大改善。在研究进行的2年间,2013年5—10月降水745 mm,为正常偏多雨年份;而2014年由于播种后110—130 d出现阶段性干旱,自然降雨量为0,5—10月累计降水仅为497 mm,优化栽培的产量增益年际间差异显著,少雨年份较正常年份产量增益损失接近50%（图7）。同时我们也发现耕层优化模式的产量增益年际间表现比冠层优化模式稳定,阶段性的水分限制,通过阻碍冠层叶片的光合作用（2014,图3）,限制了光能向化学能的转化[38,39],同时调控了干物质向籽粒中的分配（2014,图6）制约了产量的提升。而耕层优化模式表现稳定,推测为深松耕作提高了土壤通透性,增加耕层土壤对自然降水蓄含能力,代偿了水分亏缺造成的产量损失,因此协同优化耕层冠层的综合优化模式产量增益更为显著。春玉米根-冠协同优化密植高产群体,具有冠层物质分布相对均匀的结构特征,该模式协调了群体光能截获,有效减缓了中下部叶片的生长抑制,叶片生产能力显著增加,功能期延长,冠层的生产能力提高,为籽粒灌浆奠定了良好物质基础。
4 结论
综合优化模式（SWC）较常规栽培模式（RU）,显著改善了群体冠层物质的垂直结构,显著增加穗位层干物质占比,生物量重心下降,物质垂直分布更均匀;群体内穗位及以下通风透光性得到改善,下部叶片的叶绿素含量和净光合速率显著提高,功能叶片蔗糖代谢活性明显增强,籽粒活跃灌浆期有效延长,灌浆期冠层叶片生产能力提高,密植群体籽粒产量显著增加。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.fcr.2014.01.002URL [本文引用: 1]
During the past several decades, maize (Zea mays L.) grain yield (GY) has increased dramatically, while grain nitrogen concentration (GNC) has declined in modern hybrids. Genetic improvement to increase both high GY and GNC is necessary to improve maize nutritional quality. In the present study, we characterized the plant traits in three maize cultivars (YD13, ZD958, XY335) with contrasting GY and GNC in a two-year field experiment in two soils (Fu-jia-jie with infertile sandy soil and Quan-yan-gou with fertile clay soil). The hybrid YD13 as a control had low yield and high GNC. In comparison to YD13, ZD958 had higher GY but lower GNC, whereas XY335 had higher GY and similar GNC. Both ZD958 and XY335 had higher total and post-silking dry matter (DM) accumulation and N uptake than YD13, and were also characterized by delayed leaf senescence and a sustained net photosynthetic rate after silking. In addition, XY335 also had higher N remobilization efficiency (NRE) and higher photosynthetic nitrogen use efficiency (PNUE) than ZD958. It is supposed that higher NRE together with higher N and DM accumulation are the target traits to improve the modern stay-green cultivars to increase GNC without penalty in GY in the area of northeast China. Increasing PNUE of the leaves may be a possible way to maintain whole-plant photosynthesis and DM accumulation under efficient N remobilization. (C) 2014 Elsevier B.V.
[本文引用: 1]
DOI:10.1016/j.fcr.2013.12.015URL [本文引用: 2]
No tillage (NT) of summer maize (Zea mays L) is the dominant agricultural practice in the annual double-cropping system of winter wheat-summer maize in the North China Plain, and the long-term NT is often unfavorable for the growth of maize roots. The aim of this study was to evaluate the effect of 2-year-old rotary tillage (RT) and plowing tillage (PT) based at NT soil on root growth, spatial distribution, nutrients uptake and grain yield in Wuqiao of the North China Plain. PT and RT significantly increased root biomass across 0-40 cm soil profile in the whole growth stage. Lower bulk density under PT and RT was compared to under NT in the 0-20 cm soil profile, and penetration resistance under NT was significantly higher than under PT and RT in the 0-30 cm soil profile. Root length density (RLD) in the uppermost soil profile (0-10 cm) had no evident differences among tillage practices at silking stage, but RLD under PT and RT was significantly greater than under NT at maturity. Moreover, RLD and root surface density (RSD) were significantly higher under PT than under NT in the topmost layer, 10-50 cm soil profile, but there were no differences in RLD and RSD among tillage practices at the deeper soil profile below 60 cm. PT and RT markedly improved the root-bleeding sap rate in the whole growth stages in 2011 and most growth stages in 2012. In addition, NH4+ and NO3- delivery rate under PT were significantly higher than those under RT and NT in 2011 and 2012, and under RI were significantly higher than under NT in 2012. The delivery rate of P, K. Ca, Mg, Fe and Zn in bleeding sap under PT was significantly higher than those under NT at different growing stages across the two years. Our results suggested that short-term PT and RI could increase root biomass, improve root spatial and temporal distribution, and enhance nutrients uptake, which resulted in higher biomass and grain yield of summer maize in the North China Plain. (C) 2013 Elsevier B.V.
DOI:10.1016/j.fcr.2014.09.015URL [本文引用: 1]
DOI:10.1016/j.fcr.2012.01.006URL [本文引用: 1]
The overestimation of nitrogen (N) uptake requirement under a high-yield cropping system with maize (Zen mays L.) has been a driving force in the overuse of N fertilization and environmental pollution in China. A database comprising 1246 measurements collected between 2005 and 2009 from 105 on-farm and station experiments conducted in the spring maize domains of the Northeast. Northwest of China and the North China Plain, was used to evaluate N uptake requirement in relation to grain yield. Field experiments with different maize cultivars and N management forms were also carried out to assess this relationship. Across all the sites, maize yield averaged 11.1 Mg ha(-1) which was more than twice that of the national maize grain yield average of China of 5.3 Mg ha(-1) and the world average of 4.5 Mg ha(-1). Nitrogen uptake requirement per Mg grain yield averaged 17.4 kg. Considering 6 ranges of grain yield (<7.5 Mg ha(-1), 7.5-9 Mg ha(-1), 9-10.5 Mg ha(-1), 10.5-12 Mg ha(-1), 12-13.5 Mg ha(-1) and >13.5 Mg ha(-1)), N uptake requirements per Mg grain yield were 19.8, 18.1, 17.4, 17.1, 17.0 and 16.9 kg respectively. This decreasing N uptake requirement per Mg grain yield with increasing grain yield was attributed to increasing harvest index (HI) and the diluting effects of declining grain and straw N concentrations. Grain yield increased with year of cultivar release from the 1950s to the 2000s. with N uptake requirement per Mg grain yield decreasing because of declining grain and straw N concentrations. Compared with the current commercial hybrid (ZD958), the lower N uptake requirement per Mg grain yield of the N-efficient hybrid of XY335 was attributed to a lower straw N concentration while maintaining a similarly high grain yield and grain N concentration. In neither of the years was there any evidence of leaf senescence in either optimal N rate (N-opt) or excessive N rate (N-over) and there was no significant difference between N uptake of these two treatments. This indicated that excessive N application could not delay leaf senescence to sustain further grain yield increase. (C) 2012 Elsevier B.V.
DOI:10.1016/j.fcr.2010.11.006URL [本文引用: 1]
Density-dependent maize hybrids have a number of disadvantages such as the strong dependence of the crop yield on the seeding rate, the high hybrid by density interaction, and the difficulty to exploit drought-prone environments. Density-neutral cultivars are defined as those able to optimize crop yield over a wide range of plant densities. In this study we used two sets of maize hybrids, seven Romanian and seven Greek hybrids, and examine two main objectives. To evaluate under rainfed and irrigated conditions density-dependent and partially bred for density independence hybrids, in order to assess the advantages and disadvantages of the two categories. The other is to assess the reliability of a novel selection and evaluation equation in predicting the crop yield genetic potential of maize hybrids evaluated at the ultra-low plant density of 0.74 plants/m(2). The equation enables to broaden the density range for optimum productivity because it selects jointly for two attributes. One, for yield potential per plant which extends the lower limit of the optimum density range and second, for stability of performance that extends the higher limit of the optimum density range. The results of this study suggest that the optimum plant density for maize hybrids grown under drought-prone conditions is much lower than when they grow under favorable conditions, meaning that the drought-prone environments require lower plant densities for efficient use of growth resources. The advantage of breeding for density-neutral maize hybrids is that these hybrids have the potential to attain higher productivity in the drought-prone environments where the environmental resources cannot support a high plant density population and medium plant densities are most favorable. Moreover, our results show that the mean crop yield across years of the top maize Romanian and Greek hybrids evaluated at commercial plant densities could be predicted from the crop yield potential (CYP) values assessed in honeycomb trials at the low plant density. (C) 2010 Elsevier B.V.
DOI:10.2134/agronj2003.0241URL [本文引用: 2]
DOI:10.1016/j.fcr.2013.09.016URL [本文引用: 3]
Increases in maize (Zea mays L) yield over the past few decades have been associated with breeding for tolerance to progressively higher plant densities. Since high plant density exacerbates interplant competition, it has been suggested that improved resource capture through delayed senescence might be advantageous in such situations. The main objectives of this work were to determine (1) the time-course of canopy senescence, (2) post-silking C and N accumulation and (3) yield responses of contemporary maize hybrids with different expression of the stay green (SG) character grown in a range of plant densities from moderate to intense crowding stress. Three experiments consisting of a combination of different plant densities (from 6 to 10 pl m(-2)) and commercial hybrids with different timing of senescence were carried out. High density accelerated leaf senescence at the lower canopy layer. The SG hybrids delayed senescence and retained green leaves at physiological maturity at all tested densities. One of these hybrids (NK880), with a strong SG character, retained green leaves at all canopy layers, even at the lower layer exposed to limiting irradiance. Lower canopy leaves maintained high respiratory rates in NK880, while leaves of the NSG hybrid (DK682) senesced and their respiration became not detectable. At the highest tested density, the NSG DK682 achieved greater grain yields than the SG NK880.1ncreased density reduced kernel weight (MW), and this decrease was more pronounced for the SG NK880 (6-18% comparing 10 vs. 8 pl m-2). In spite of delayed senescence in NK880, no hybrid differences were found for post-silking dry matter accumulation and plant dry matter at physiological maturity. Unexpectedly, plant nitrogen content (Nc) at harvest was similar (Exp. I) or even lower (P< 0.05, Exp. II) in the SG NK880. This was the result of lower net N accumulation during the post-silking period (Exp. I) or lower Nc achieved at silking (Exp. II) in the SG NK880. A strong positive relation was found between KW and N concentration in kernels, with %N in kernels being below the critical N concentration to achieve potential KW (around 1.4%) in the SG hybrid. This suggests that yield in NK880 was limited by N. In the SG genotype, N remobilization from vegetative organs did not seem to compensate for the N deficit for optimum grain growth. In summary, at high densities the NK880 hybrid displayed a strong, constitutive SG character, even if it accumulated less N, and senescence delay was not reflected in higher grain yield. (C) 2013 Elsevier B.V.
DOI:10.1016/0378-4290(95)00022-IURL [本文引用: 1]
DOI:10.1626/pps.1.233URL [本文引用: 1]
DOI:10.2134/agronj2005.0336URL [本文引用: 2]
DOI:10.1016/j.eja.2014.05.007URL [本文引用: 1]
Maize breeding during the past 50 years has been associated with a delay of leaf senescence, but it is not clear whether this trait is likewise associated with higher grain yield in modern hybrids. Post-silking growth, leaf area dynamics, photosynthetic parameters and yield were compared in modern maize hybrids differing in canopy senescence rate. In the first two experiments, four hybrids were grown in the field at Balcarce, Argentina (37 degrees 45' S, 58 degrees 18 W). In spite of differences in chlorophyll retention and photosynthesis of the ear leaf, post-silking growth and grain yield were very similar in all four hybrids while kernel N concentration was lower in the later-senescing hybrids. In a third experiment, a later-senescing (NK870) and an earlier-senescing (DK682) hybrid were grown to analyze the potential photosynthetic contribution of delayed leaf senescence. Leaf area and chlorophyll content were larger in NK870, especially at the lower canopy level (0.75 m above the ground). However, hybrids did not differ for canopy light interception. Because photosynthetic photon flux density below 1 m above the ground was less than 10% of incident radiation and photosynthesis quantum yield did not change during senescence, the potential photosynthetic output of lower leaves below 1 m was very low. Lower leaves of NK870 had N concentrations higher than those needed to sustain photosynthesis at the light conditions below 1 m. Therefore, we show that delayed senescence does not necessarily improve post-silking C accumulation because; (i) canopy light interception is not reduced by senescence except at very late stages of grain filling; (ii) contrasting hybrids show more pronounced senescence differences at canopy levels receiving less than 10% of incident radiation; (iii) delayed senescing hybrids present lower kernel N concentrations while extra N is retained in leaves exposed to a light limiting micro-environment. Delayed senescence at lower canopy levels may be unproductive, at least under non-stressing conditions. (C) 2014 Elsevier B.V.
DOI:10.1016/j.fcr.2010.10.009URL [本文引用: 1]
Nitrogen (N) use efficiency (NUE), defined as grain produced per unit of fertilizer N applied, is difficult to predict for specific maize (Zea mays L) genotypes and environments because of possible significant interactions between different management practices (e.g., plant density and N fertilization rate or timing). The main research objective of this study was to utilize a quantitative framework to better understand the physiological mechanisms that govern N dynamics in maize plants at varying plant densities and N rates. Paired near-isogenic hybrids [i.e., with/without transgenic corn rootworm (Diabrotica sp.) resistance] were grown at two locations to investigate the individual and interacting effects of plant density (low-54,000; medium-79,000; and high-104,000 pl ha(-1)) and sidedress N fertilization rate (low-0; medium-165; and high-330 kg N ha(-1)) on maize NUE and associated physiological responses. Total aboveground biomass (per unit area basis) was fractionated and both dry matter and N uptake were measured at four developmental stages (V14, R1, R3 and R6). Both plant density and N rate affected growth parameters and grain yield in this study, but hybrid effects were negligible. As expected, total aboveground biomass and N content were highly correlated at the V14 stage. However, biomass gain was not the only factor driving vegetative N uptake, for although N-fertilized maize exhibited higher shoot N concentrations than N-unfertilized maize, the former and latter had similar total aboveground biomass at V14. At the R1 stage, both plant density and N rate strongly impacted the ratio of total aboveground N content to green leaf area index (LAI), with the ratio declining with increases in plant density and decreases in N rate. Higher plant densities substantially increased pre-silking N uptake, but had relatively minor impact on post-silking N uptake for hybrids at both locations. Treatment differences for grain yield were more strongly associated with differences in R6 total biomass than in harvest index (HI) (for which values never exceeded 0.54). Total aboveground biomass accumulated between R1 and R6 rose with increasing plant density and N rate, a phenomenon that was positively associated with greater crop growth rate (CGR) and nitrogen uptake rate (NUR) during the critical period bracketing silking. Average NUE was similar at both locations. Higher plant densities increased NUE for both medium and high N rates, but only when plant density positively influenced both the N recovery efficiency (NRE) and N internal efficiency (NIE) of maize plants. Thus plant density-driven increases in N uptake by shoot and/or ear components were not enough, by themselves, to increase NUE. (C) 2010 Published by Elsevier B.V.
DOI:10.1016/j.fcr.2014.12.005URL [本文引用: 1]
DOI:10.1016/j.cj.2014.04.006URL [本文引用: 1]
DOI:10.5424/sjar/20110904-050-11URL [本文引用: 1]
Planting pattern affects canopy structure of crops and influences other physiological characteristics such as light interception and radiation use efficiency. In the current paper, the effects of planting patterns on the canopy structure, light interception, and photosynthetic characteristics at silking stage of two maize (Zea mays L.) cultivars (Beiyu288 and Xianyu 335) were examined in three planting patterns narrow wide rows of (1) 30 cm + 170 cm (P1, 6.4 plants m(-2)), and (2) 40 cm+90 cm (P2, 6.4 plants m(-2)), and uniform row of 65 cm (control, i.e. CK, 6.4 plants m(-2)). The ratio of leaves perpendicular to rows was highest in PI and the leaf orientation value in P1 was constant and slightly lower in P2 compared with that in CK. Although a decrease in the total intercepted photosynthetically active radiation (IPAR) of P1 was found in the two cultivars, more incoming PAR was detected at the middle-low canopy strata of P I. The apparent quantum yield and the net photosynthesis rate (P(N)) in P1 and P2 were significantly higher than those in CK. The P(N) and stomatal conductance (g(s)) values in P1 were significantly higher than those in CK, and the intercellular CO(2) concentration decreased with an increase in P(N). These results indicated that narrow-wide row planting patterns improved the canopy structure, allowed more IPAR to reach the middle low strata of the canopy, and enhanced the leaf photosynthetic characteristics of maize crops at silking stage compared with CK.
DOI:10.1111/j.1399-3054.2009.01333.xURLPMID:20051030 [本文引用: 3]
Mathematical models of light attenuation and canopy photosynthesis suggest that crop photosynthesis increases by more uniform vertical irradiance within crops. This would result when a larger proportion of total irradiance is applied within canopies (interlighting) instead of from above (top lighting). These irradiance profiles can be generated by Light Emitting Diodes (LEDs). We investigated the effects of interlighting with LEDs on light interception, on vertical gradients of leaf photosynthetic characteristics and on crop production and development of a greenhouse-grown Cucumis sativus'Samona' crop and analysed the interaction between them. Plants were grown in a greenhouse under low natural irradiance (winter) with supplemental irradiance of 221 micromol photosynthetic photon flux m(-2) s(-1) (20 h per day). In the interlighting treatment, LEDs (80% Red, 20% Blue) supplied 38% of the supplemental irradiance within the canopy with 62% as top lighting by High-Pressure Sodium (HPS)-lamps. The control was 100% top lighting (HPS lamps). We measured horizontal and vertical light extinction as well as leaf photosynthetic characteristics at different leaf layers, and determined total plant production. Leaf mass per area and dry mass allocation to leaves were significantly greater but leaf appearance rate and plant length were smaller in the interlighting treatment. Although leaf photosynthetic characteristics were significantly increased in the lower leaf layers, interlighting did not increase total biomass or fruit production, partly because of a significantly reduced vertical and horizontal light interception caused by extreme leaf curling, likely because of the LED-light spectrum used, and partly because of the relatively low irradiances from above.
URL [本文引用: 2]
A field experiment was conducted to compare the effects of planting geometries on the canopy structure, functional properties and yield of the spring maize variety Zhengdan958 planted under high density condition. Four planting geometries were adopted: one plant per clump opposite in adjacent rows (DD), one plant per clump staggered in adjacent rows (DC), two plants per clump opposite in adjacent rows (SD), and two plants per clump staggered in adjacent rows (SC). The results indicated that in the SD and SC treatments, the vertical distribution of canopy exhibited a spindleshaped morphological tendency with an accumulation of the dry matter in stem and leaf in the layer of 0-90 cm (under ear leaf) and 90-180 cm (ear leaf)， the stemleaf angle under the lamina of the ear increased significantly by 2.4°-3.4°. The treatments clumps with two plants (SD and SC) provided more niche space for each plant and enhanced tolerance to highdensity planting. Compared with the conventional DD planting pattern, leaf area index (LAI) and chlorophyll relative content (SPAD) values before the filling stage for clumped and scattered planting geometries were lower, while the opposite phenomenon occurred at the filling stage. Compared to the control, the grain yields in these clumped and scattered planting treatments were increased by 11.2%-12.7% but were not significantly different, largely due to increased lodging resistance and higher ear number and thousandkernel weight. Our results confirmed that the population structure and shoot morphological structure under highdensity condition were effectively regulated by the clumped and scattered planting geometries, which improved photosynthesis capacity of middledown leaves at the filling stage and revealed a great potential of highyielding structure and tolerance to highdensity planting.
URL [本文引用: 2]
A field experiment was conducted to compare the effects of planting geometries on the canopy structure, functional properties and yield of the spring maize variety Zhengdan958 planted under high density condition. Four planting geometries were adopted: one plant per clump opposite in adjacent rows (DD), one plant per clump staggered in adjacent rows (DC), two plants per clump opposite in adjacent rows (SD), and two plants per clump staggered in adjacent rows (SC). The results indicated that in the SD and SC treatments, the vertical distribution of canopy exhibited a spindleshaped morphological tendency with an accumulation of the dry matter in stem and leaf in the layer of 0-90 cm (under ear leaf) and 90-180 cm (ear leaf)， the stemleaf angle under the lamina of the ear increased significantly by 2.4°-3.4°. The treatments clumps with two plants (SD and SC) provided more niche space for each plant and enhanced tolerance to highdensity planting. Compared with the conventional DD planting pattern, leaf area index (LAI) and chlorophyll relative content (SPAD) values before the filling stage for clumped and scattered planting geometries were lower, while the opposite phenomenon occurred at the filling stage. Compared to the control, the grain yields in these clumped and scattered planting treatments were increased by 11.2%-12.7% but were not significantly different, largely due to increased lodging resistance and higher ear number and thousandkernel weight. Our results confirmed that the population structure and shoot morphological structure under highdensity condition were effectively regulated by the clumped and scattered planting geometries, which improved photosynthesis capacity of middledown leaves at the filling stage and revealed a great potential of highyielding structure and tolerance to highdensity planting.
URLPMID:18820698 [本文引用: 2]
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DOI:10.1371/journal.pone.0129231URLPMID:26098548 [本文引用: 1]
The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0-20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20-30 cm layer. Soil moisture in the 20-50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20-50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants' ability to access nutrients and water. An optimal combination of deeper deployment of roots and resource (water and N) availability was realized where the soil was prone to leaching. The correlation between the depletion of resources and distribution of patchy roots endorsed the SS tillage practice. It resulted in significantly greater post-silking biomass and grain yield compared to the RT and NT treatments, for summer maize on the Huang-Huai-Hai plain.
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URLPMID:12753969 [本文引用: 1]
DOI:10.1016/S0378-4290(96)01056-8URL [本文引用: 1]
URLPMID:20164899 [本文引用: 1]
[本文引用: 1]
[本文引用: 1]
DOI:10.3724/SP.J.1006.2013.01284URL [本文引用: 1]
Dry matters production after anthesis is very important for maize yield. To further clear its role in super high yield condition (high density with ample water and fertilizer supply), we compared yield components in three cultivated varieties, including Denghai661 (DH661), Zhongdan 909 (ZD909) and 970. According to the theory of yield performance, the post-anthesis yield performance parameters were analyzed. The changes of net photosynthetic rate, the contentsof chlorophyll, soluble sugar, starch, total C and N were measured in the ear leaf. The results showed thatthere were significant differences in the yield among three varieties. Varieties with higher yield (DH661 and ZD909) had higher kernel weight per ear, while DH661 had more grains per ear (466.7) and ZD909 had higher 1000-kernel weight (392.7 g).The post-anthesis dry matter production and its partitive ratios in grains were both higher in the two varieties with higher yield. Yield performance analysis showed that the mean leaf area index (mLAI) and leaf area duration (LAD) were significantly and positively correlated with post-anthesis dry matter production and yield. The chlorophyll, total carbon and total nitrogen content decreased slowly and C/N ratio increased slowly in the two varieties with higher yield. The net photosynthetic rate (Pn) was relatively higher in the ear leaves in the whole grain filling stage. The photosynthate not only supplied to kernels but also stored as starch in leaves at the early phase of grain filling. Only when Pn declined at late phase of grain filling the accumulated starch began to degrade for the kernel filling. These results indicated that the balance between carbon and nitrogen metabolism, and slowing down the photosynthate decrease in ear leaf are responsible for maintaining higher mLAI and LAD, resulting in higher yield.
DOI:10.3724/SP.J.1006.2013.01284URL [本文引用: 1]
Dry matters production after anthesis is very important for maize yield. To further clear its role in super high yield condition (high density with ample water and fertilizer supply), we compared yield components in three cultivated varieties, including Denghai661 (DH661), Zhongdan 909 (ZD909) and 970. According to the theory of yield performance, the post-anthesis yield performance parameters were analyzed. The changes of net photosynthetic rate, the contentsof chlorophyll, soluble sugar, starch, total C and N were measured in the ear leaf. The results showed thatthere were significant differences in the yield among three varieties. Varieties with higher yield (DH661 and ZD909) had higher kernel weight per ear, while DH661 had more grains per ear (466.7) and ZD909 had higher 1000-kernel weight (392.7 g).The post-anthesis dry matter production and its partitive ratios in grains were both higher in the two varieties with higher yield. Yield performance analysis showed that the mean leaf area index (mLAI) and leaf area duration (LAD) were significantly and positively correlated with post-anthesis dry matter production and yield. The chlorophyll, total carbon and total nitrogen content decreased slowly and C/N ratio increased slowly in the two varieties with higher yield. The net photosynthetic rate (Pn) was relatively higher in the ear leaves in the whole grain filling stage. The photosynthate not only supplied to kernels but also stored as starch in leaves at the early phase of grain filling. Only when Pn declined at late phase of grain filling the accumulated starch began to degrade for the kernel filling. These results indicated that the balance between carbon and nitrogen metabolism, and slowing down the photosynthate decrease in ear leaf are responsible for maintaining higher mLAI and LAD, resulting in higher yield.
DOI:10.1016/j.fcr.2013.09.016URL [本文引用: 1]
Increases in maize (Zea mays L) yield over the past few decades have been associated with breeding for tolerance to progressively higher plant densities. Since high plant density exacerbates interplant competition, it has been suggested that improved resource capture through delayed senescence might be advantageous in such situations. The main objectives of this work were to determine (1) the time-course of canopy senescence, (2) post-silking C and N accumulation and (3) yield responses of contemporary maize hybrids with different expression of the stay green (SG) character grown in a range of plant densities from moderate to intense crowding stress. Three experiments consisting of a combination of different plant densities (from 6 to 10 pl m(-2)) and commercial hybrids with different timing of senescence were carried out. High density accelerated leaf senescence at the lower canopy layer. The SG hybrids delayed senescence and retained green leaves at physiological maturity at all tested densities. One of these hybrids (NK880), with a strong SG character, retained green leaves at all canopy layers, even at the lower layer exposed to limiting irradiance. Lower canopy leaves maintained high respiratory rates in NK880, while leaves of the NSG hybrid (DK682) senesced and their respiration became not detectable. At the highest tested density, the NSG DK682 achieved greater grain yields than the SG NK880.1ncreased density reduced kernel weight (MW), and this decrease was more pronounced for the SG NK880 (6-18% comparing 10 vs. 8 pl m-2). In spite of delayed senescence in NK880, no hybrid differences were found for post-silking dry matter accumulation and plant dry matter at physiological maturity. Unexpectedly, plant nitrogen content (Nc) at harvest was similar (Exp. I) or even lower (P< 0.05, Exp. II) in the SG NK880. This was the result of lower net N accumulation during the post-silking period (Exp. I) or lower Nc achieved at silking (Exp. II) in the SG NK880. A strong positive relation was found between KW and N concentration in kernels, with %N in kernels being below the critical N concentration to achieve potential KW (around 1.4%) in the SG hybrid. This suggests that yield in NK880 was limited by N. In the SG genotype, N remobilization from vegetative organs did not seem to compensate for the N deficit for optimum grain growth. In summary, at high densities the NK880 hybrid displayed a strong, constitutive SG character, even if it accumulated less N, and senescence delay was not reflected in higher grain yield. (C) 2013 Elsevier B.V.
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DOI:10.3389/fpls.2018.01326URL [本文引用: 1]
