,*, 周宝元*, 马玮*, 李从锋*, 丁在松*, 孙雪芳*中国农业科学院作物科学研究所 / 农业部作物生理生态与栽培重点开放实验室, 北京 100081Theoretical and technical models of quantitative regulation in food crop production system
ZHAO Ming,*, ZHOU Bao-Yuan*, MA Wei*, LI Cong-Feng*, DING Zai-Song*, SUN Xue-Fang*Institute of Crop Sciences, Chinese Academy of Agricultural Sciences / Key Laboratory of Crop Physiology and Production, Ministry of Agriculture, Beijing 100081, China通讯作者:
收稿日期:2018-06-12接受日期:2019-01-12网络出版日期:2019-02-11
| 基金资助: |
Received:2018-06-12Accepted:2019-01-12Online:2019-02-11
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赵明, 周宝元, 马玮, 李从锋, 丁在松, 孙雪芳. 粮食作物生产系统定量调控理论与技术模式[J]. 作物学报, 2019, 45(4): 485-498. doi:10.3724/SP.J.1006.2019.83051
ZHAO Ming, ZHOU Bao-Yuan, MA Wei, LI Cong-Feng, DING Zai-Song, SUN Xue-Fang.
进入21世纪以来, 作物生产已从单纯追求产量转向“高产、优质、高效、生态、安全”多目标协同发展, 特别是高产与光温水肥等资源高效利用的结合已成为农业绿色可持续发展的主导方向。生产目标的转变必然导致作物生产过程的变化, 以适应当前的生产发展形势。然而, 作物生产系统是一个作物-环境-社会相互交织的复杂系统, 作物生产的高产和高效通常是矛盾的、难以协调统一的整体。近30年来, 虽然我国粮食产量由于机械化、精确灌溉、化学肥料等技术的应用有了大幅度的增长[1], 但是生产中滥用化肥农药、不合理耕作导致土壤耕层恶化、品种多乱杂等现象日益加剧, 造成光热肥水资源与作物生长发育不协调[2,3,4], 土壤耕层状况与支撑高产群体能力不协调[5,6], 作物群体与个体、源库器官不协调[7,8], 高产不稳产、丰产不高效、产量不平衡等问题日益突出。要解决制约当前生产的突出问题, 实现作物生产系统绿色可持续发展, 必须加强作物生产系统理论指导, 用系统论的观点, 把作物生产过程看作一个系统, 即作物生产系统, 深入研究作物生产系统各要素的相互作用规律, 并探求适宜的调控措施, 定量优化各要素之间的协同关系, 充分挖掘作物生产系统的生产潜能与高效协调功能。本文总结当前作物生产调控理论与技术, 并提出了基于作物生产系统整体构成的“气候-土壤-作物”协同定量调控体系, 以期为实现作物高产高效可持续生产提供理论依据。
1 作物产量与品质形成分析理论
1.1 作物产量形成分析理论
产量的形成是作物群体物质生产过程中的最终结果, 也是作物栽培学研究的主题。作物产量分析理论在深入认识作物产量形成的内在规律、探索作物高产的限制因素以及作物高产实践中发挥着重要的指导作用。自1928年Mason和Maskell提出了“源库”学说后, 在近代作物栽培的理论探讨中, 常以源、库、流三因素的关系来阐明作物产量形成的规律, 探索实现高产的技术途径, 进而挖掘作物的产量潜力。王志敏等[9]将近100年来产量分析概括为3条研究路线, 即发育分析(产量构成因素)、生长与物质生产分析(光合性能)、源库关系分析, 并认为这3条路线应该整合统一。产量构成理论将禾谷类作物的产量分解为穗数、单穗粒数和粒重[10], 让人们可以直观地了解产量构成因素, 并从这些因素的变化中了解产量的形成规律。光合性能理论指出作物的光合生产力取决于单位土地面积的光合面积、光合速率、光合时间、呼吸消耗和经济系数5个方面, 对作物群体的物质生产和分配过程进行定量描述[11,12], 并将它们与经济产量联系起来[13], 即产量 = (光合面积×光合时间×光合速率-呼吸消耗)×经济系数, 揭示了产量形成的本质。源库理论将物质生产与产量形成紧密联系起来, 系统考虑产量形成, 避免了光合性能和产量构成分析各自的片面性, 同时提出了源指标(叶面积指数、光合势、光合速率、净同化率和叶源量等)、库指标(单位面积穗数、单位面积粒数、潜在库容和籽粒充实度等)以及源库关系指标(粒叶比、势粒比、势容比以及潜在库源比等), 借助生理学和分子生物学方法对作物源库调节机制和源库关系进行了深入研究[14,15,16,17]。然而, 这3个理论各存在一定的不足, 产量构成理论仅从作物库方面强调了产量构成因素, 而与产量的物质来源联系不紧密; 光合性能理论只强调了作物群体的物质生产, 忽略了产品器官在物质分配中的主导作用, 光合作用与产量之间的关系不清楚; 源库理论虽然将二者联系起来, 但关于源库关系的解析不够系统, 不能对作物产量的形成做出全面系统的解释。
我国科学家在作物高产理论方面开展了广泛的研究, 取得了重要的进展。曹显祖等[18]在水稻上证明限制产量提高有多种类型并存, 指出作物高产存在源限制型、库限制型和源库共同限制型。凌启鸿等[19,20]提出了作物群体质量概念, 确立花后物质积累量作为群体质量的核心指标, 认为水稻高产更高产的方向是既有高的最适叶面积指数(源), 又有高的粒叶比(源/库)。张洪程等[21,22]揭示了不同类型水稻品种叶龄进程与产量形成对应关系, 系统阐明了优化水稻群体生长动态, 精确稳定前期生长量, 合理增加中期高效光合生产量, 增强后期物质生产积累能力、籽粒灌浆充实能力和群体支撑能力的高产形成规律。于振文等[23,24]系统研究了高产条件下小麦旗叶与根系衰老的生理机制, 阐明了小麦衰老的生理特点及其与粒重形成的关系, 探索出延长缓衰期、保持较长光合速率高值期, 增加开花至成熟阶段的干物质积累及其向穗部的分配, 提高粒重的高产栽培途径。董树亭等[25,26,27]深入研究了玉米群体光合性能与产量形成的关系, 提出了增强花后群体光合能力, 延长群体光合高值持续期, 减少群体呼吸消耗的高产途径。赵明等[28]将玉米高产实现途径归结为结构性、功能性和结构与功能同步3条挖潜途径, 其中结构性挖潜途径是通过构建密植优化群体结构, 增库、增源定向栽培; 功能性挖潜途径是通过提高群体质量, 保证后期光合物质的长期快速积累; 结构功能同步挖潜途径是在合理密植的情况下, 提高植株个体活力, 实现群体和个体功能协调, 达到“稳穗、足粒和高结实率”。在综合分析产量分析三理论内在联系的基础上, 赵明提出了产量分析的“三合结构”模式[29], 将各理论有机地结合起来, 系统地阐述了作物源与库各因素间的内在联系, 并建立了相应的定量表达公式[30], 弥补了各理论独立存在的不足, 为作物产量定量化分析提供了新的思路和方法。王志敏等[9]进一步将产量与资源利用效率相联系, 建立了基于资源利用效率的产量分析模式, 即产量=单位面积可供资源(投入)量×资源截获率×资源转化效率×收获指数, 为分析产量与各种资源效率的关系提供了范式。
1.2 作物品质形成分析理论
作物品质主要受遗传因素决定, 但其他因素如栽培措施、土壤情况、环境条件等对作物品质的影响也较大。源库理论反映了同化物输入与输出的特点, 是作物产量和品质形成的基础, 因此协调源库关系也是作物品质形成的关键。淀粉、蛋白质和脂类等是评价作物营养品质的主要指标。研究表明, 小麦、水稻籽粒的淀粉积累速率决定于同化器官向籽粒供应同化物的能力(源限制)和籽粒本身的淀粉合成能力(库限制), 且籽粒的淀粉合成能力与品种及籽粒中可溶性碳水化合物含量密切相关[31,32]。陈洁等[32]分析了水稻植株氮素积累与转运的生理过程, 认为水稻籽粒蛋白质积累速率由源限制的氮源(花前植株同化氮素和花后贮存氮素的转运)和库限制的氮素积累速率决定。赵俊晔、王小燕和石玉等[33,34,35]系统研究了小麦品质生理, 提出增加拔节至开花期植株氮素积累量, 促进灌浆中后期蛋白质降解, 及营养器官贮存氮素向籽粒的转移, 调节籽粒适宜氮/硫比, 提高谷蛋白大聚合体含量及谷蛋白与醇溶蛋白含量比值, 改善蛋白质品质的途径。李文峰等[36]认为, 由于植株积累氮素和棉籽积累的碳水化合物组成了棉籽油分, 因此棉子油分的含量是由棉籽干物质积累速率和油分合成速率共同决定。
生态环境对作物淀粉、蛋白质的形成有非常重要的作用。研究表明, 小麦籽粒淀粉含量主要受开花至成熟期日均温与总降雨量的影响, 蛋白质含量受开花期至成熟期的平均日较差、日平均温度、积温、总降雨量和总日照时数等气候因子的影响[37]; 高温通过抑制淀粉合成过程中某些酶失活, 从而抑制玉米籽粒淀粉合成[38]。李文峰等[39]认为影响棉籽油分含量的主要因子为品种、温度、太阳辐射和施氮量。
2 作物与环境协同调控理论
作物生长发育状况与其所在地区的生态条件密切相关[40,41,42]。然而, 作物生长过程中各种环境条件(光、热、水、肥、气、土壤等)具有时空变化的特点, 作物栽培的目的就是通过各种措施使作物与资源变化相吻合, 充分合理地利用有限的资源, 提高作物产量和资源利用效率。2.1 作物与气候协同调控理论
作物品种、播期、生育期等与光、温、水资源的匹配度是影响作物生长发育及产量与品质形成的主要因素[42]。虽然光温水等生态条件是人为不可控的条件, 但可通过调节作物播/收期、品种等措施调控生长季光温水等分配, 协调光温水与作物生长发育的关系, 促进作物产量潜力和资源利用效率提升[43]。前人开展了大量关于作物生长与光温资源匹配机理的研究, 并探索了资源高效利用的调控途径。在北方春玉米区, 李少昆等[44,45]通过10余年系统研究探明了高产群体生长发育与区域光辐射量和积温的定量匹配关系, 提出了密植高产群体质量指标及控倒防衰、提高整齐度的光温匹配调控途径。在黄淮海冬小麦-夏玉米一年两熟制下, 王树安[46]在北部资源亏缺区建立了冬小麦-夏玉米“双晚”技术模式, 将冬小麦播种期推迟至10月中旬, 夏玉米收获期推迟至9月底至10月初, 周年产量达到15,000 kg hm-2以上, 光温资源生产力分别提高64%和124%。另外, 河北农业大学[47,48,49]探明了海河平原高产小麦冬前积温和行距配置的光温利用效应, 揭示了高产玉米生育期调配的光温利用规律, 提出了小麦“减温、匀株”和玉米“抢时、延收”的光温高效利用途径。河南农业大学[50,51,52]探明了黄淮区小麦、玉米高产群体生育和资源利用特征, 提出了小麦“品种播期双改”、玉米“延时收获”的周年资源高效利用途径, 发挥小麦冬前分蘖成穗的优势, 充分利用玉米收获至小麦播种前的资源, 实现周年光热水资源高效利用。王志敏等[53,54]揭示了干旱胁迫下小麦非叶器官光合耐逆机制, 阐明了增加非叶光合面积, 构建大群体、小株型结构, 拔节前控水促根下扎, 充分发挥深层种子根的“根系泵”作用的水分高效利用机制。董树亭等[38,55-56]揭示了生态因素对玉米生长发育和产量品质形成的影响, 明确了花后高温寡照是限制黄淮海地区产量提高的关键因素, 提出了改套种为直播、适时晚收、延长灌浆时间的栽培理论。赵明等[43,57-58]探明了气候因子对玉米源库性能的影响机制, 建立了叶面积系数动态变化的积温模型, 为作物产量性能与气候因素协同的定量化研究提供了范式。在南方稻麦和双季稻两熟区, 许轲等[59]通过分期播种试验, 研究了播期与品种类型对水稻产量、生育期及温光资源利用的影响, 根据区域温光资源特征初步确定了不同类型品种适宜播种期。张洪程等[60,61]在探明粳稻温光利用优势的基础上提出将双季晚稻的籼稻品种改成具有较高耐寒性、分蘖力较强的粳稻品种, 发挥粳稻生育期较籼稻长的优势, 充分利用晚稻季光温资源, 提升周年产量和温光资源利用率的理论与技术途径。
2.2 作物与土壤协同调控理论
在大田环境中土壤理化特性时空变化较大, 直接影响作物的生长发育与产量形成。土壤容重是表征土壤物理环境及资源状态的一个重要的指标[62]。土壤容重的增加造成作物根系难以下扎伸展, 影响根系对水分和养分的吸收, 增加了根系早衰, 造成地上部减产[6,63]。土壤耕作可以优化调整土壤结构, 为作物生长与建成创造一个优良的环境[64]。20世纪80年代以来, 在我国主要农区, 常采用免耕或机械浅层旋耕的耕作方式, 大大提高了生产效率, 但导致了土壤耕层变浅, 并产生坚硬的犁底层, 阻碍根系向深层土壤下扎[5,6]。张洪程等[65,66]在江苏六大农区5~11年的连续定位研究中, 以少免耕等轻简耕作栽培方式下作物前期早发而中后期早衰的特点阐明了土根系统中养分与根系向土表富集、中后期土壤养分供应减弱与根系活力下降, 导致植株光合生产能力减弱的早衰机理。2008年国家玉米产业技术体系对全国玉米主产区土壤耕层状况调查探明, 我国主要玉米田土壤耕层存在着“耕层浅、犁底层坚实、耕层有效土量少”等特点。近年来, 深松或深翻耕作作为一种有效的土壤改良耕作措施得到广泛应用。研究表明, 深松(翻)可打破犁底层, 显著改善耕层土壤结构, 使根系在纵向扩充生长空间, 以满足对地上部分营养物质和水分的供应[67,68]。赵明等[67,68,69]探明了条带深旋耕作对土壤理化特性、作物根系生长发育及产量性能指标的调控效应, 并创新了玉米条带深旋密植精播一体化技术, 显著改善土壤耕层环境, 大大提高生产效率。王立春等[70,71]经多年定位试验研究阐明了苗带紧行间松、松紧兼备型耕层模式对土壤水、气调节机制, 通过全面深松和苗带局部重镇压的方式来满足春玉米生长对耕层土壤的生态需求。然而, 大量研究表明, 没有一种耕作方式能够适用于所有的土壤环境, 土壤耕作方式不同对土壤的理化及生物特性影响不同[72]。
作物生长发育所必需的各种速效养分主要来自土壤, 而肥料是土壤养分的主要来源, 因此协调作物生长发育与土壤养分及施肥的关系是进一步挖掘作物产量潜力的关键。凌启鸿等[20]和张洪程等[21]探明了叶龄模式与水肥调控的关系, 提出水稻精确定量施肥技术途径, 解决了高产水稻总施氮量精确定量及各生育期定量施用问题。于振文等[23-24,34]探明了小麦生长发育与氮肥吸收的同步关系, 提出了氮肥后移, 增加追肥氮比例, 延缓后期衰老, 提高粒重的技术途径。赵明等[73,74]提出通过滴灌分期施肥和深施缓释肥的方式实现氮肥后移, 维持玉米花后较高的氮素积累能力和光合生产能力, 同步提高产量和氮肥利用效率的理论与技术途径。张福锁等[75,76]根据各种养分资源特征进行养分管理, 综合利用各种养分资源, 从过去以“(肥料)投入-(作物)产出关系”的黑箱管理逐渐走向对土壤-作物-环境系统养分过程的实时定量化调控, 并建立了小麦、玉米、水稻等主要作物的养分资源综合管理技术体系, 显著提高了作物产量、肥料资源利用效率及生态效益。
3 作物生产调控技术
如上所述, 协调作物“源、库、流”的关系, 使作物群体和个体的发展达到源足、库大、流畅, 才可能获得高产。然而, 作为一个有机整体, 作物的各个性状相互联系、相互制约。对于作物产量与品质的提升, 必须明确突破的技术途径, 并通过精确的调控措施实现作物物质生产因素与产量构成因素间的高效协调。3.1 产量形成调控技术
近年来, 我国作物栽培科学家通过一线研究建立了一批高产栽培技术体系。例如, 张洪程等[77]针对高密度毯状小苗秧质弱、植伤趋重导致超级稻生育不充分而制约潜力发挥的问题, 通过“三控”(控种、控水、化控)标准化育秧、“三因”(因种、因地、因苗)精确化机插与“三早”(早促、早控、早攻)模式化调控等关键技术创新, 构建了超级稻机械化高产栽培技术体系。章秀福等[78]建立水稻“垄畦高密、扩库强源”超高产模式, 通过垄畦栽培, 宽行窄株密植, 优化群体结构, 改善群体通透条件; 以水调肥、调气, 强根健株, 实现增穗增粒的水稻双季超高产。王法宏等[79]建立冬小麦“垄沟立体种植”超高产模式, 垄沟种植改善土壤理化性状, 改善群体冠层结构, 增加了单位面积的麦穗容纳量和边行优势, 延缓后期衰老, 有利于穗粒数和千粒重的提高。赵明等[80]针对密植导致倒伏、早衰等限制玉米产量潜力发挥的问题, 从同步改善土壤耕层环境与冠层结构角度出发, 创新了“三改”深松和“三调”密植关键技术, 建立了“深耕层-密冠层”、“控株型-促根系”及“培地力-高肥效”的密植高产高效技术模式。李少昆等[81]创新了以耐密品种、合理密植、群体质量调控为核心, 配套精量点播、滴水出苗、化学调控、机械施肥、绿色防控、秸秆还田、机械收获、烘干收储等关键技术, 构建了玉米密植高产全程机械化绿色生产技术体系。董志强等[82]针对东北春玉米低温冷害导致生育期推迟、密植高产群体倒伏早衰的问题, 以控株增密和抗逆防衰为目标, 建立了展六叶和展九叶两次喷施化控剂的“双重定向”化控技术, 在逆境条件下维持较高的产量和光温利用效率。3.2 资源高效利用技术
在光温水资源高效利用方面, 河北农业大学[47,48,49]针对华北地区一年两熟光温水资源紧张导致周年产量潜力挖掘不足的问题, 建立小麦“匀株密植晚播”、玉米“抢时增密延收”技术及两熟“减灌降耗提效”水分高效利用技术, 实现周年光温水资源优化配置与高效利用。河南农业大学[50,51,52]针对黄淮区光温等资源特点, 提出了小麦“双改技术”与夏玉米“延衰技术”, 创建出小麦-夏玉米两熟高产栽培技术体系, 实现周年光热资源高效利用和小麦夏玉米均衡增产。王志敏等[53,54]建立了冬小麦“四统一”高产技术模式, 通过调整灌溉次数和施肥结构, 构建大群体发挥主茎大蘖优势、非叶绿色器官的光合耐逆机能和初生根持续吸收功能, 实现小麦种植高产、高效、低耗和简化。杨建昌等[83]建立了水稻干湿交替节水灌溉技术, 全生育期进行轻干-湿交替灌溉, 减少灌溉次数和灌水量, 提高产量和水分利用效率。在提高化肥利用率方面也取得了一些成果, 如测土配方施肥、氮肥深施、平衡施肥、水肥一体化等技术, 在一定程度上减缓了肥料用量的增加, 提高了肥料利用效率。于振文等[23,24]针对我国小麦生产中氮肥过量, 且底施比例过大导致氮肥利用率低的问题, 建立了冬小麦氮肥后移技术, 通过减少底肥氮数量、增加追肥氮比例, 生育前中期低定额后期控制灌溉, 精量施用氮、硫、磷、钾肥, 减少了土壤氮素淋溶, 提高了水肥利用率。杨建昌等[84]和黄见良等[85]建立水稻实时实地氮肥管理技术, 根据目标产量确定总氮肥用量及生育各阶段氮肥分配比例, 关键生育时期根据水稻叶色值(SPAD或LCC)适当调整氮肥用量, 解决后期倒伏和早衰问题, 显著提高水稻产量和氮肥利用效率。张福锁等[75-76,86]建立了土壤-作物综合管理技术, 基于土壤养分实时监测和作物养分需求特征进行根层养分调控, 在不增加氮肥用量的同时提高作物产量。另外, 近年来大田作物缓/控释肥等新型肥料的研究迅速发展, 被认为是减少肥料损失、提高肥料利用率的有效措施[74,75,76,77,78,79,80,81,82,83,84,85,86,87]。
3.3 精确定量栽培技术
张洪程等[21]创立了生育进程、群体动态指标、栽培技术措施“三定量”与作业次数、调控时期、投入数量“三适宜”为核心的水稻丰产精确定量栽培技术体系, 使水稻生产管理“生育依模式、诊断有指标、调控按规范、措施能定量”。曹卫星等[88,89]围绕作物主要生长指标的特征光谱波段和光谱参数、定量监测模型、实时调控方法、监测诊断产品等开展了深入系统的研究, 集成建立了基于反射光谱的作物生长光谱监测与定量诊断技术体系, 实现了作物生长与生产力预测的数字化及作物管理方案设计的精确化。赵明等[80]建立了玉米全生育期产量性能各指标定量化动态标准, 研发出冠层系统的实时监测与管理决策专用软件(玉米生长定量化动态分析及其高产高效管理系统), 实现了玉米合理冠层的定量化和动态监测及调控。4 作物生产系统定量调控体系
综上所述, 前人关于作物生产调控理论与技术方面进行了大量的研究探索, 取得了重大进展, 形成了一批有代表性的成果, 在一定程度上大大提高了作物产量和资源利用效率。然而, 目前大部分研究往往仅从作物生产某一方面揭示产量与品质形成规律及其与环境的关系, 并进行相应栽培技术的创新, 缺乏从作物生产系统整体角度出发进行的系统化研究, 未形成系统的作物生产理论与技术体系, 难以适应当前的生产发展形势, 作物生产调控理论与技术亟须进一步深化与完善。为此, 笔者在归纳总结前人研究与本人30多年研究结果的基础上, 于2016年全国青年作物栽培与学术研讨会上提出了作物生产系统“气候-土壤-作物”协同定量调控体系, 简称“三协同”调控体系(图1), 其核心是从作物生产系统整体出发, 建立“气候-土壤-作物”之间定量化指标, 并通过相应的调控措施协同优化三者之间的关系, 使整个作物生产系统的功能高效协调。图1
新窗口打开|下载原图ZIP|生成PPT图1作物生产系统“三协同”定量优化体系示意图
Fig. 1“Three Collaboration” theoretical models of crop production systemRa: radiation; AT: accumulated temperature; DR: distribution ratio; TPPE: photothermic production potential equivalence; DM: dry matter.
4.1 “三协同”定量调控体系构成特点
作物生产系统是以气候、土壤和农作物为物质基础, 通过采取多种调控技术措施, 以获取作物某一部分的产量为目的, 同时兼顾经济、社会和生态效益, 有利于农业可持续发展的生产系统[90]。笔者在深入分析作物生产系统的整体性、有序性和综合性特征, 及系统内作物与气候、土壤的供求机制与关系调控的基础上, 建立了“三协同”调控体系。“三协同”调控体系具有系统性特点。作物生产系统的功能主要取决于系统的整体性、有序性和综合性, 及系统内作物与气候、土壤的供求机制与关系调控[91]。为构建更加合理的作物生产系统结构, 促进系统功能不断提升, 可将作物生产系统分为“气候-作物”、“土壤-作物”、“群体-个体”3个子系统(图1)。根据逻辑关系又将其分为3个层次, “气候-作物”系统为第一层次, “土壤-作物”系统为第二层次, “群体-个体”系统为第三层次, 3个子系统有机结合构成“三协同”体系。
“三协同”调控体系具有可定量特点。作物生产系统通过物质循环和能量交换形成作物与作物、作物与环境、环境与环境作用关系[90], 这些过程可通过某种手段精确定量, 其中气候-作物协同以光温资源分配率与利用效率的“两率”为核心定量化指标, 土壤-作物协同以土壤供给力与冠层生产力的“两力”为核心定量化指标, 群体-个体协同以作物群体内部与个体器官间结构功能的“两体”为核心定量化指标。以作物产量、光温水肥资源利用效率及经济效益等定量指标构建作物生产系统协同性的综合评价体系。
“三协同”调控体系具有可调节特点。在认识作物生产系统各要素相互作用规律基础上, 可通过构建合理的调控措施, 使作物生产系统各个组成部分之间协调平衡、相互促进, 总体功能不断提升。气候-作物协同主要通过调节作物生长季光热资源的配置与利用以实现光温高效利用; 土壤-作物协同通过改良土壤结构和肥水控制实现高产高效同步; 群体-个体协同通过品种、种植方式调控确保群体与个体及个体器官间协同, 实现产量潜力挖掘。
4.2 “三协同”定量调控指标
4.2.1 气候-作物协同定量调控指标 气候-作物协同定量调控以提高季节间光温资源分配率与季节内光温资源利用率的“两率”为核心。首先, 在季节间资源有效分配方面, 笔者通过分析三大粮食作物主产区34个试验点7年定位试验产量和气候因素数据, 探明了气候因子与作物产量的定量关系, 创立了以积温为主, 兼顾辐射和降水分配的季节间资源优化配置定量指标, 并建立了相应的计算公式[92]。积温分配率(TDR) = 单季积温量(Tx)/周年积温总量(T) (1)
辐射分配率(RDR) = 单季辐射量(Rx)/周年辐射总量(R) (2)
降雨分配率(PDR) = 单季降雨量(Px)/周年降雨总量(P) (3)
积温比值(TR) = 第一季积温量(T1)/第二季积温量(T2) (4)
辐射比值(RR) = 第一季辐射量(R1)/第二季辐射量(R2) (5)
降雨比值(PR) = 第一季降雨量(P1)/第二季降雨量(P2) (6)
在季节内资源高效利用方面, 笔者通过分析年际间、地区间生态条件的差异及其资源与产量的定量关系, 在2007年首次提出了表征季节内资源利用效率的“光温生产潜力当量”的概念, 即TPPE = Y/TPPy (TPPE为光温生产潜力当量, Y为作物实际产量, TPPy为光温生产潜力)[93]; 为表征资源变化与作物需求匹配关系, 提出了季节内积温满足率(TSR)的概念及相应公式。
通过分析全国不同区域的不同两熟模式的播期调控试验和产量差分析(N = 293), 明确了不同两熟模式周年季节间有效积温、辐射分配(表1)[92,94]; 同时进一步明确了季节内三大作物光温生产潜力当量值(图2), 这些指标为作物资源高效利用的定量调控提供指导。
Table 1
表1
表1不同种植模式积温、辐射优化分配表
Table 1
| 模式 Cropping system | 积温 Accumulated temperature | 辐射 Radiation | |||
|---|---|---|---|---|---|
| 周年总量 Annual amount (°C) | 两季比值 Ratio of two seasons | 周年总量 Annual amount (MJ m-2) | 两季比值 Ratio of two seasons | ||
| W-M | 5330.3±79.3 | 46:54 | 4169.5±145.9 | 60:40 | |
| D-D | 5275.1±139.8 | 43:57 | 4336.6±300.9 | 58:42 | |
| W-R | 5237.7±100.1 | 36:64 | 4490.1±116.9 | 53:47 | |
| M-M | 4974.3±151.9 | 50:50 | 3428.7±103.5 | 58:42 | |
| M-R | 5439.7±53.0 | 54:46 | 3381.3±197.2 | 55:45 | |
| R-R | 5645.3±272.5 | 48:52 | 3455.3±272.5 | 54:46 | |
| r-r | 5250.1±156.1 | 71:29 | 3420.2±160.5 | 72:28 | |
新窗口打开|下载CSV
图2
新窗口打开|下载原图ZIP|生成PPT图2三大作物不同产量水平光温生产潜力当量值
Fig. 2Photothermic production potential equivalence of wheat, maize, and rice with different levels of yield
4.2.2 土壤-作物协同定量调控指标 作物产量决定于冠层生产力与耕层供给力“两力”的平衡, 冠层耕层的同步优化是密植高产的主要途径。“两力”构成的原则是构建耕层-冠层、土壤-作物协调优化的体系, 耕层供给力与作物冠层生产力匹配。以提高耕层供给力为核心, 挖掘冠层作物生产力, 以最终提高产量实现高产高效。
首先, 利用研发的作物耐密性鉴定方法, 解析土壤基础地力、目标产量与作物种植密度的定量关系(y = abxxc)[95], 基于作物土壤基础产量(土壤供给力)与高产高效目标产量(冠层生产力)的差值(图3, ΔY)确定实现目标产量的作物群体容纳量与养分供给量。根据产量与密度定量关系确定密度增量, 根据产量与养分定量关系(百千克籽粒需养分量)确定施肥量, 实现基于土壤基础地力的高产高效定量栽培。
图3
新窗口打开|下载原图ZIP|生成PPT图3土壤-作物协同定量优化模式图
Fig. 3Models of collaboration quantitative optimization between soil and crop
进而利用35年肥效长期监测平台揭示不合理耕作导致土壤犁底层上移(2.8~4.9 cm)、容重增加(7%~35%)、有机质质量变差(腐殖化和脂族化程度高而疏水化程度低)、贫钾富磷、耕层土壤酸化(pH下降1.3~1.5)、真菌/细菌比值降低(碳源不足)等关联变化是主产区农田地力下降、高产支撑力不足的主要机制[70,71]。由此提出“培肥地力、减量施肥”的丰产高效技术策略, 及深厚耕层构建与有机物料输入相结合的地力提升途径。同时, 利用自主研发的根-土空间分布取样方法与分析体系[67,68,69]对不同作物生产系统农民田块和高产高效田块长期定位试验分析, 明确了两熟区高产高效农田比农民田块土壤耕层厚度增加28%~35%, 容重降低18%~20%, 有机质含量提高13%~20%, 氮磷钾含量平均提高19%~30% (表2)。同时, 提出以容重、贯穿阻力为核心的土壤结构生产力指标及氮磷钾与有机质含量空间分布为核心的养分生产力指标来确定土壤供给力。
Table 2
表2
表2不同区域不同田块土壤理化特征
Table 2
| 土壤特征 Soil characteristics | 东北春玉米区 Spring maize in Northeast China | 黄淮海小麦-玉米区 Wheat/maize in the Huang-Huai-Hai Plain | 长江中下游稻作区 Rice in Yangtze Plain | |||
|---|---|---|---|---|---|---|
| 一般农田 Farmers’ field | 高产高效 Optimized field | 一般农田 Farmers’ field | 高产高效 Optimized field | 一般农田 Farmers’ field | 高产高效 Optimized field | |
| 物理特征Physical characteristics | ||||||
| 耕层深 Depth of topsoil (cm) | 15.1 | 26.5 | 17.2 | 27.3 | 14.5 | 25.0 |
| 容重 Soil volume weight (g cm-3) | 1.43 | 1.21 | 1.37 | 1.16 | 1.54 | 1.28 |
| 耕层有效土量 Effective amount of tilling soil (×106 kg hm-2) | 1.97 | 3.15 | 2.21 | 3.07 | 2.01 | 3.18 |
| 化学特征Chemical characteristics | ||||||
| 有机质 Organic matter (%) | 1.81-4.61 | 2.63-6.67 | 0.78-1.26 | 1.12-1.68 | 0.95-2.45 | 2.01-3.81 |
| 全氮 Total nitrogen (%) | 0.08-0.32 | 0.21-0.52 | 0.03-0.09 | 0.08-0.15 | 0.06-0.13 | 0.12-0.17 |
| 速效磷 Available phosphorus (mg kg-1) | 4-10 | 8-15 | 2.8-7.8 | 6.7-13.2 | 2.8-6.7 | 5.5-8.5 |
| 速效钾 Available potassium (mg kg-1) | 92-136 | 116-251 | 91-136 | 141-215 | 53-102 | 76-142 |
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4.2.3 “群体-个体”协同定量调控指标 作物冠层结构是作物个体、群体产量性能数量与质量的综合体现。作物理想冠层的本质特征是群体总库容量(群体总粒数)大、花后物质积累量高, 这就要求在前中期保持适宜叶面积系数, 提高成穗率和结实率, 后期增大光合势、提高净同化能力和物质运转与分配效率。因此, 优化协调个体与群体以及叶源系统与库容系统之间的关系对作物高产高效栽培具有重要意义。
笔者在多年试验研究的基础上, 确定了“群体-个体”协同定量优化的核心为协调作物群体内部及个体叶穗系统、物质生产与分配的关系[96]。该分析模式主要包括以下3个方面。一是, 明确了作物产量形成是根、茎、叶、穗4个系统相互依存, 在根茎的吸收与支撑能力保障的前提下, 其中叶系统光合物质生产能力与穗系统籽粒形成的光合产物分配是挖掘产量潜力的关键。二是, 基于系统间关系分析作物产量与叶穗系统定量关系, 构建了叶穗系统协同定量公式(Y = MALI×D×MNAR×HI = EN× GN×GW)及三大作物高产高效群体叶穗系统指标体系(表3)[30], 其中等式左边(MALI×D×MNAR×HI)表示叶系统光合物质生产过程, 等式右边(EN×GN× GW)表示穗系统产量形成过程, 其中MLAI和MNAR指标为生育期内某一时段的平均值, 可以作为生长过程的动态变量进行实时监测与调控; 三是, 研究表明高产高效群体具有较高的后期物质生产能力, 花后干物质积累量/生育期总干物质积累量为: 玉米0.62、小麦0.45、水稻0.51。在此基础上, 提出了通过高效物质分配与高效结实机制以挖掘作物后期物质生产能力为核心的挖潜技术途径, 根据作物花后干物质积累量/生育期总干物质积累量比值指标来选择确定具体技术措施, 如氮肥后移、深松改良土壤、优化种植方式及水肥一体化等, 调控后期养分供应和群体的光分布, 维持个体较高的光合速率, 延缓衰老, 从而维持群体高效物质生产功能, 提高作物产量。
Table 3
表3
表3高产高效群体结构和功能参数
Table 3
| 作物 Crop | 叶系统 Leaf system | 穗系统 Spike system | 产量 Grain yield (kg hm-2) | ||||
|---|---|---|---|---|---|---|---|
| MLAI | MNAR | HI | EN (×104 hm-2) | GN (No. ear-1) | GW (g) | ||
| 春玉米 Spring maize | 4.29 | 5.94 | 0.49 | 8.69 | 411.3 | 342.8 | 13121.3 |
| 夏玉米 Summer maize | 3.42 | 6.07 | 0.52 | 7.98 | 443.8 | 362.6 | 12408.4 |
| 冬小麦 Winter wheat | 2.72 | 5.19 | 0.46 | 691.0 | 32.0 | 45.0 | 10110.2 |
| 水稻 Rice | 3.81 | 3.94 | 0.51 | 373.4 | 129.7 | 22.5 | 11306.8 |
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4.3 “气候-土壤-作物”协同互作途径
以上建立的气候-作物、土壤-作物和群体-个体协同定量指标, 可分别从光温资源定量配置、基础地力与目标产量协调、源库产量平衡等3个方面指导作物品种与播期合理搭配、地力培肥与肥水调控、群体结构与功能优化等“三协同”调控技术创新。进而通过三类技术组装构建生产技术模式, 每个模式均包括气候-作物、土壤-作物和群体-个体三方面的调控技术。由于各类别都有多个单项技术, 通过三类技术的组装可形成多种搭配组合, 利用通径分析和主成分分析对技术的优先序和互作效应进行评价[8]。在阐明三类技术的协同互作机制基础上, 筛选出区域适宜的作物丰产高效生产技术模式, 进行大田示范验证与推广应用。4.4 “三协同”定量调控体系应用与效益评价
4.4.1 “三协同”定量调控体系应用 以黄淮海冬小麦-夏玉米周年高产高效种植模式为例, 介绍“三协同”定量调控体系在作物生产实践中的应用, 为实现作物“高产、优质、高效、生态、安全”生产提供新思路。针对黄淮海地区周年光温资源区域差异大、利用效率低, 常年免耕或浅旋耕导致土壤容重增加, 秸秆还田难导致播种质量差等交织并存的问题, 基于“三协同”调控体系指导, 创新光温配置、秸秆还田培肥、改行调密等技术, 在北部集成以小麦冬前积温调减-玉米后期积温调增、两季秸秆还田培肥和减耗节水、小麦缩行距匀株距密植等关键技术为核心的小麦-玉米调温节水、匀株密植技术模式; 在中部集成以小麦早播增温-玉米晚收增产、两季统筹培肥补灌、小麦宽行稀植-玉米窄行密植等关键技术为核心的小麦早播稀植、玉米密植晚收周年灌溉模式; 在南部集成以小麦稀植早播-玉米增密晚收、简耕覆盖保水等关键技术为核心的小麦简耕覆盖、玉米免耕密植周年雨养模式。在河南、河北两省分别示范3套模式, 较传统模式产量提高8.1%~12.2%, 光温生产效率提高6.9%~11.3%, 水分生产效率提高9.2%~14.1%, 经济效益增加2205元 km-2, 实现两季均衡增产增效。
4.4.2 “三协同”定量调控体系效益评价 国家粮食丰产科技工程项目组在优化调整柯布-道格拉斯生产函数、DEA-Malmquist指数法等评价模型基础上, 建立了粮食生产全要素评价专用模型(Yt = Aeδ t \(K_{t}^{x} \ L_{t}^{β} \ M_{t}^{γ}\) ), 依据该模型可对“三协同”定量调控体系指导构建的技术模式进行全要素(包括种子、化肥、农药、水电、柴油、机械、人工等)生产率、土地利用率、气候资源利用效率和经济效益等进行评价。应用生命周期评价方法(Life Cycle Assessment, LCA)对技术模式的整地播种、田间管理和收获等环节的资源消耗、物质投入及环境排放进行评价。
5 作物生产系统调控体系研究展望
经过长期的作物生产研究与实践, 我国在水稻、小麦和玉米等主要粮食作物研究中, 已经建立了丰富的栽培技术体系, 在确保粮食安全和农民增收中发挥了巨大的作用, 但生产中尚缺乏基于作物生产系统整体性的系统化、定量化作物栽培理论与技术, 在一定程度上限制了作物高产高效优质等多目标的实现。笔者在基于前人研究和本人30多年研究结果的基础上构建的作物生产系统气候-土壤-作物“三协同”定量优化体系, 通过定量分析作物生产过程与气候、土壤等环境因素的内在关系, 将“气候-作物”、“土壤-作物”和“群体-个体”三者协同优化, 形成了系统的作物生产理论体系, 弥补了现有理论与技术的不足, 为未来作物生产调控理论与技术的创新提供了思路。然而, 如何将现有的理论与技术与这一体系高度融合, 进一步完善该理论体系, 并有效应用于生产实践, 尚有待更深入的研究与探讨。气候-土壤-作物“三协同”定量调控理论初步建立了光温资源定量配置、基础地力与目标产量协调、源库产量平衡3个方面的定量指标, 分别指导作物品种布局与播/收期调整、地力培肥与肥水调控、群体结构与功能等调控技术创新。然而, 气候-土壤-作物“三协同”定量调控理论还需要进一步完善, 在气候-作物协同方面, 需要进一步阐明作物生长发育各阶段与光温资源匹配关系及其定量指标; 在土壤-作物协同方面, 加强研究作物产量形成与土壤生物特性和水肥动态变化的关系及其定量指标; 在群体-个体协同方面, 从不同器官及其组织形态与功能、关键生理与分子调控机制方面认识群体与个体协同关系; 在气候-土壤-作物三者协同方面, 阐明三者协同调控机制, 建立相应的定量调控指标; 加强“三协同”技术体系在作物品质形成方面的指导; 加强该理论模式指导高产高效关键技术创新和区域特色技术模式集成, 对整个体系的经济效益、社会效益和生态效益进行评价。
致谢: 特别感谢吉林省农业科学院王立春研究员和王永军研究员、河南师范大学李春喜教授、河南农业大学尹钧教授、河北农业大学李雁鸣教授、山东省农业科学院张宾研究员、天津市农业技术推广站侯海鹏研究员、天津农学院葛均筑博士对本项研究工作的大力支持。
参考文献 原文顺序
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[本文引用: 1]
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DOI:10.1016/j.agrformet.2011.06.013URL [本文引用: 1]
Recent crop model projections have shown that crop production may benefit from warming, especially in the high latitudes, but hard evidence is limited. In this study we conducted correlation and regression analyses of climate records of seventy-two meteorological stations and records of corn yield over the period 1965–2008 in Northeast China. It was found that over these forty-four years, the diurnal mean, minimum and maximum temperatures during corn growing season increased on average by 0.31°C, 0.42°C and 0.23°C every ten years, respectively. No significant change in precipitation was found, although differences between years were large. The daily minimum temperature was the dominant factor to corn production. Corn yield was significantly correlated with the daily minimum temperature in May and September. According to a regression analysis of the anomalies of corn yield and air temperature, a 1.0°C increase in daily minimum temperature in May or September will lead to an increment of 303kgha611 or 284kgha611 in corn yield, respectively. Corn varieties with longer growth duration will profit most from the climatic changes but agronomic practices may have to be modified to address expected weather extremes such as droughts and periods with heavy rainfall.
DOI:10.1016/j.indcrop.2006.12.003URL [本文引用: 1]
Rotation of winter wheat ( Triticum aestivum L.) and summer maize ( Zea mays L.) is the prevailing double-cropping system in the North China Plain. Typically, winter wheat is planted at the beginning of October and harvested during early June. Maize is planted immediately after wheat and harvested around 25th of September. The growing season of maize is limited to about 100 110 days. How to rectify the sowing date of winter wheat and the harvest time of summer maize are two factors to achieve higher grain yield of the two crops. Three-year field experiments were carried out to compare the grain yield, evapotranspiration (ET), water use efficiency (WUE) and economic return under six combinations of the harvest time of summer maize and sowing date of winter wheat from 2002 to 2005. Yield of winter wheat was similar for treatments of sowing before 10th of October. Afterwards, yield of winter wheat was significantly reduced ( P < 0.05) by 0.5% each day delayed in sowing. The kernel weight of maize was significantly increased ( P < 0.05) by about 0.6% each day delayed from harvest before 5th of October. After 10th of October, kernel weight of maize was not significantly increased with the delay in harvest because of the lower temperature. The kernel weight of maize with thermal time was in a quadratic relationship. Total seasonal ET of winter wheat was reduced by 2.5 mm/day delayed in sowing and ET of maize was averagely increased by 2.0 mm/day delayed in harvest. The net income, benefit ost and net profit per millimetre of water used of harvest maize at the beginning of October and sowing winter wheat around 10th of October were greater compared with other treatments. Then the common practice of harvest maize and sowing winter wheat in the region could be delayed by 5 days correspondingly.
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DOI:10.1016/j.fcr.2011.06.023URL [本文引用: 1]
New insights into changes in physiological processes associated with genetic gains in yield potential are essential for improved understanding of yield-limiting factors. Our field study was conducted at two sites with three N levels and 15 modern wheat ( Triticum aestivum L.) varieties. The goal was to evaluate yield components, time courses of dry matter production, and N accumulation among different yield categories, and to determine physiological processes associated with yield–trait relationships. Close correlations were observed between yield and dry matter production after the stem elongation stage, particularly post-anthesis. Similar close correlations were observed between grain yield and N accumulation over the whole growing season, except for the re-greening stage. No positive correlation was found between yield and harvest index. Differences in dry matter production among different yield categories began at anthesis; differences in N accumulation emerged even earlier. We conclude that consistent increases in dry matter production (especially post-anthesis) and N accumulation are crucial for further improvements in wheat yield–trait relationships.
DOI:10.1016/j.fcr.2016.08.012URL [本文引用: 2]
Subsoiling tillage practices and wide-narrow planting patterns could greatly improve grain yield through increasing post-silking dry matter accumulation of spring maize (Zea maysL.) under high plant density. However, the relationship between increased yield and vascular bundles structure, post-silking matter transport efficiency has not been unknown. Therefore, a field experiment was conducted on the Northeast plain of Liaoning Province in China in 2013 and 2014 to investigate the effects of four cultivation modes on post-silking matter transport under high plant density (105,000 plants ha611). A widely grown maize hybrid Zhongdan 909, which exhibits high grain yield and tolerance to high plant density, has been used in our study. The four cultivation modes were (1) traditional rotary tillage (20cm) plus uniform plant spacing (60cm; RU; control); (2) subsoiling tillage (35–40cm) plus uniform plant spacing (60cm; SU); (3) traditional rotary tillage (20cm) plus wide-narrow (80+40cm) plant spacing (RW); and (4) subsoiling tillage plus wide-narrow plant spacing (SW). Compared to RU, wide-narrow planting (RW, SW) significantly optimized the canopy structure at silking, while SU and SW significantly optimized the soil structure, thus improved the photosynthetic rate and canopy radiation use efficiency (RUE), and post-silking dry matter accumulation (+5.2% [SU], +6.5% [RW], and +13% [SW]), and simultaneously reduced the C/N ratio in stems at maturity (614% [SU], 6127% [RW] and 6139% [SW]), which led to the balancing of C and N in organs of maize at grain filling stage. Moreover, it also enhanced the differentiation of the vascular bundle system at the early growth stage, and maintained its function after silking by the better environmental conditions, which greatly improved the matter transport efficiency (+42%), and increased the grain filling rate. As a result, the yield for SU, RW, and SW increased by 5%, 7.5%, and 22%, respectively, compared to RU. These suggested that the optimization practices noticeably increased the canopy RUE after silking for spring maize by improving matter transport efficiency, stem vascular structure, and maintaining the balance between C and N metabolism, which eventually increased the grain yield under high plant density conditions. It might provide information of appropriate cultivation practices in enhancing grain yield for maize.
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[本文引用: 2]
DOI:10.1017/S0021859600003828URL [本文引用: 1]
It is unlikely that as a formulated problem any consideration of settled crop-husbandry is of greater antiquity than the cereal yield problem. In its broad form it embraces all the possible means of increasing the output of grain per unit area. The earliest civilizations of Mesopotamia and Egypt must have been compelled to explore these means as soon as they began to encounter the limitations to cultivable area which dwelling in fixed communities imposed. Wheat and barley were their principal food stuffs so that the cereal yield problem, the most comprehensive concern of present-day agriculture, goes back to the remotest antiquity. It must have evoked incessant effort along divers lines and the cumulative result is appreciable from a comparison of the best cereal races of to-day and the forms which like Hordeum spontaneum and Triticum dicoccum dicoccoides have been regarded as the progenitor types. Unfortunately it is not possible to trace back very far the sequence of the solution of the problem as constituted by improvements in husbandry and the utilization of better cereal forms. Fragments of information may be culled from the writings of various periods but they are of doubtful value. The author's reliability is often in question, the unit of measure uncertain, and even the identity of the crop a matter of doubt. Herodotus' well-known story, passed on from another, of increases of 200 and even 300 fold yielded by barley in Mesopotamia in 500 B.c. is possibly the oldest fragment. It is difficult to interpret but it gains colour from the further statement that the leaves of the plant were of the width of four fingers. Concerning progress in England, while reasonably precise information goes back no further than forty years, there are widely separated records of sufficient worth to indicate the historical trend. It has been deduced from the Manorial Records that at the time when that system had become established there was a flat rate of about ten bushels per acre for wheat. Much later, when Sir Charles Davenant compiled An Essay upon the Probable Methods of making a People Gainers in the Ballance of Trade (published 1699), he computed the eat produce of eight million acres of arable land to be 79 million bushels of grain.
DOI:10.1093/jxb/erf064URLPMID:12379789 [本文引用: 1]
Rate of grain filling in terms of dry mass accumulated per panicle per day was measured in field-grown rice in the dry season in the Philippines and compared to rates of light-saturated photosynthesis per unit leaf area (P-max) measured at 350 mul 1(-1) CO2 for 21 d after flowering. Five new plant type (tropical japonica) varieties (NPT) and one indica variety (IR72) were used and these gave some variation in rates and patterns of grain filling. A rapid grain-filling phase (RGFP) occurred approximately 10 d after flowering in most varieties. There was no consistent relationship in any variety between the rate of grain-filling and Pmax and chlorophyll content, both of which remained mostly unchanged throughout grain filling. Significant declines in the amount of total leaf protein and ribulose bisphosphate carboxylase-oxygenase (Rubisco) occurred, but these did not occur at the same time as the RGFP in all varieties. A decrease in the ratio of chlorophyll a/b preceded these changes and a transient rise in chlorophyll content was also observed in four varieties at this time. There was no significant change in leaf non-structural carbohydrate content during or following the RGFP. It is concluded that the decline in Rubisco and protein content in NPT was not reflected in photosynthetic activity. Hence in these field experiments Rubisco accumulated to a level in excess of photosynthetic requirements, serving as a store of nitrogen for grain filling.
DOI:10.1016/S0378-4290(02)00024-2URL [本文引用: 1]
Average commercial maize yield in the US has increased from about 1 Mg/ha in the 1930s to about 7 Mg/ha in the 1990s. Although the increase has been the result of both genetic and agronomic-management improvements, we contend that most of this improvement is the result of the genotype management interaction. The genetic improvement in maize yield is associated neither with yield potential per se, nor with heterosis per se, but it is associated with increased stress tolerance, which is consistent with the improvement in the genotype management interaction. The potential for future yield improvement through increased stress tolerance of maize in the US is large, as yield potential is approximately three times greater than current commercial maize yields. The mechanism by which maize breeders have improved stress tolerance is not known, but we speculate that increased stress tolerance may have resulted from the selection for yield stability. Stability analyses were performed on a number of high-yielding maize hybrids, including three hybrids that have been involved in some of the highest maize yields recorded in producers fields, to examine the relationship between yield and yield stability. Results of the stability analyses showed that high-yielding maize hybrids can differ in yield stability, but results do not support the contention that yield stability and high grain yield are mutually exclusive.
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DOI:10.1016/j.tplants.2003.12.008URLPMID:15102372 [本文引用: 1]
Molecular transformation is commonly offered as a hope to overcome the apparent stagnation in crop yield potential. A basic understanding of the resource limits imposed on crops and the yield hierarchy going from gene expression to harvestable yield leads to a rather negative view that transformations of a few, or even of a complex of genes will result directly in major yield increases. Forty years of biochemical and physiological research illustrate the great difficulty in translating research at the basic level into improvements in crop yield. However, there are a few cases where physiological research has led to improved crop cultivars with increased yield. These successes are instructive in highlighting key elements required to achieve success in developing crop cultivars for increased yield.
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DOI:10.1016/j.fcr.2005.11.006URL [本文引用: 1]
Grain nitrogen (N) concentration is one of the main quality parameters of wheat grains. Since few reports have quantified the processes of N accumulation in both grain and vegetative parts in wheat ( Triticum aestivum L.), this study was undertaken to develop a dynamic model for simulating plant N uptake and grain N accumulation in wheat by focusing on the variation of N accumulation rate in individual grains. Five different experiments involving genotypes, N fertilization rates and water regimes were conducted to support model development and model evaluation. The model proposed that the rate of individual grain N accumulation was determined by the N availability and the interaction of influencing factors as temperature, water and nitrogen conditions within plants over the time course. N availability of individual grain was the sum of N uptake and remobilization from the vegetative parts post-anthesis. Post-anthesis N uptake exhibited an exponential relationship to grain weight and N accumulation at the time of anthesis which was determined by pre-anthesis N uptake. N remobilization from the leaves was assumed to decrease with leaf area index (LAI). N remobilization from the stems and chaffs (spikes without grains) was dependent on the curvilinear or linear decreases of the N concentrations and the weights of stems and chaffs during grain filling. Two genotypic parameters were incorporated into the model, i.e. the maximum rate of individual grain N accumulation and physiological filling duration of specific cultivars. The overall performance of the model was validated with independent data sets from three field experiments spanning 3 years and comprising various genotypes, nitrogen and water levels. The RMSE values for model components with all treatments were averaged 11%, indicating a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for grain N accumulation and protein formation in different wheat cultivars under various growing conditions.
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DOI:10.3354/cr00823URL [本文引用: 1]
Change in thermal conditions can substantially affect crop growth, cropping systems, agricultural production and land use. In the present study, we used annual accumulated temperatures > 10 degrees C (AAT10) as an indicator to investigate the spatio-temporal changes in thermal conditions across China from the late 1980s to 2000, with a spatial resolution of 1 x 1 km. We also investigated the effects of the spatio-temporal changes on cultivated land use and cropping systems. We found that AAT10 has increased on a national scale since the late 1980s, Particularly, 3.16 x 10(5) km(2) of land moved from the spring wheat zone (AAT10: 1600 to 3400 degrees C) to the winter wheat zone (AAT10: 3400 to 4500 degrees C). Changes in thermal conditions had large influences on cultivated land area and cropping systems. The areas of cultivated land have increased in regions with increasing AAT10, and the cropping rotation index has increased since the late 1980s. Single cropping was replaced by 3 crops in 2 years in many regions, and areas of winter wheat cultivation were shifted northward in some areas, such as in the eastern Inner Mongolia Autonomous Region and in western Liaoning and Jilin Provinces.
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DOI:10.1007/s10584-011-0385-1URL [本文引用: 2]
AbstractIn the North China Plain, the grain yield of irrigated wheat-maize cropping system has been steadily increasing in the past decades under a significant warming climate. This paper combined regional and field data with modeling to analyze the changes in the climate in the last 40 years, and to investigate the influence of changes in crop varieties and management options to crop yield. In particular, we examined the impact of a planned adaptation strategy to climate change -“Double-Delay” technology, i.e., delay both the sowing time of wheat and the harvesting time of maize, on both wheat and maize yield. The results show that improved crop varieties and management options not only compensated some negative impact of reduced crop growth period on crop yield due to the increase in temperature, they have contributed significantly to crop yield increase. The increase in temperature before over-wintering stage enabled late sowing of winter wheat and late harvesting of maize, leading to overall 4–6% increase in total grain yield of the wheat-maize system. Increased use of farming machines and minimum tillage technology also shortened the time for field preparation from harvest time of summer maize to sowing time of winter wheat, which facilitated the later harvest of summer maize.
DOI:10.2134/agronj2015.0196URL [本文引用: 2]
Variations in weather conditions could alter maize (Zea mays L.) growth and development. This study was conducted to determine the eco-physiological determinants of variations in maize yield with weather conditions, and the relationship between grain yield, dry matter production, and climatic factors. Eight sowing dates were set at 15- to 20-d intervals from mid-March to mid-July during 2012 and 2013 in the Huang-Huai-Hai region of China. When the sowing date was delayed, the yield increased initially and later declined, and the greatest yield was obtained at 12 June (SD6) sowing date for both years. The increased yield for SD6 was mainly attributed to the 1000-kernel weight and post-silking dry matter production, which were mainly influenced by the post-silking plant growth rate. Variations in temperature and radiation were the primary factors that infl uenced the post-silking dry matter production of maize, and eventually influenced grain yield. High temperatures (daily maximum temperature [Tmax] > 28.1C) during postsilking under early sowing conditions and low temperatures (daily minimum temperature [Tmin] < 17.7C) under late sowing conditions combined with low radiation (accumulated radiation [Ra] < 1 005.4 MJ m2) decreased the post-silking plant growth rate, thereby decreasing the dry matter production and grain yield. Therefore, when the sowing was done from 25 May to 27 June, the relatively higher maize yield would be obtained. We conclude that variations in weather conditions (temperature and radiation) from silking to maturity significantly affect the plant growth rate of maize, influence post-silking dry matter production, and grain yield.
DOI:10.1016/j.fcr.2013.01.003URL [本文引用: 1]
Environmental conditions greatly affect the growth of maize. To examine differences in phenological responses of maize (Zea mays L.) to climatic factors under different environmental conditions as induced by latitude, experiments were conducted from 2007 to 2010 at 34 sites in seven Chinese provinces located in the north spring maize region of China between latitudes 35°11′ and 48°08′N in the cultivation of hybrid zhengdan958 (ZD958). Latitude is an important geographical factor which significantly affects temperature, sunshine hours, and the duration of crop growth. The findings of this study indicate that for every 1° increase in the latitude, northward, the growth durations of sowing to emergence and emergence to silking were significantly increased by 0.7 d and 1.25 d, respectively as a consequence of lowering temperatures (mean, maximum, and minimum temperatures). Reproductive growth duration (silking to maturity), which was significantly correlated with the precipitation, decreased by 0.8 d with each 1° increase in latitude northward. At higher latitudes, the number of growing degree days (GDD) of maize vegetative growth duration (emergence to silking) was significantly higher, and the GDD of the reproductive growth duration were significantly lower. The average photoperiod during the photoperiod-sensitive phase of maize development across all the experimental sites was 14.9h with a range of 13.7–15.6h. Total leaf numbers increased from 18.7 to 23.7 with an average of 21.0 across all experimental sites. Significant and positive linear relationships were found to occur between both latitude and photoperiods and latitude and total leaf number. In the north China spring maize region, the mean growth duration of ZD958 was 143.73 d, which constituted 82.8% of the frost free period, the percentage increasing with higher latitude. These findings strongly indicate that in order to ensure high and stable production of maize in the north spring maize region of China, with its limited heat resources, especially in the high-latitude regions, there is a need to cultivate short-growth-duration cultivars.
DOI:10.2135/cropsci2012.12.0688URL [本文引用: 1]
Environmental conditions have important effects on maize (Zea mays L.) growth. To examine spatial variation in maize yield and aboveground biomass and to understand differences in the response of maize yield and aboveground biomass to climatic factors under various ecological conditions, we conducted experiments from 2007 to 2010 at 34 locations in seven provinces in the spring maize region of northern China between 35 degrees 11' N lat and 48 degrees 08' N lat. We used a most widely cultivated maize hybrid ZD958. The maize yield and aboveground biomass (presilking and postsilking) were found to be strongly influenced by locations. A nonlinear relationship existed between the maize yields and latitude. Maize yield was the greatest (12.19 Mg ha(-1)) at 39 degrees 08' N lat, and the corresponding presilking and postsilking aboveground biomass at this location were 143.41 and 215.35 g per plant, respectively. Variations in the harvest index (HI) and 1000-kernel weight were the main reasons for yield latitudinal trends. Among the climatic factors, air temperature had the best relationships with variations in maize yield, HI, and 1000-kernel weight. With latitudes increasing northward, presilking aboveground biomass affected by growth duration length and accumulated solar radiation increased significantly. The aboveground biomass of postsilking stage that was affected by the maximum temperature, daily mean temperature, and growing degree days decreased significantly with latitudes increasing northward. However, there were no significant changes of total aboveground biomass with latitudes increasing northward.
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DOI:10.1016/S2095-3119(12)60025-2URL [本文引用: 2]
To provide base for adjusting the sowing date, achieving the yield potential of wheat cultivars with different growth characteristics, and improving the utilization rate of natural resource in the North China Plain (NCP), a 4-yr field experiment of growing degree-days (GDD) before winter (realized through different sowing dates) with three wheat (Triticum aestivum L.) cultivars of each type of semi-winterness and weak springness was carried out at 20 test experimental sites (32°4′N-36′1′N) of Henan Province in the NCP. The results showed that: (i) yield of semi-winterness wheat was significantly higher than weak springness wheat (**P<0.01); (ii) there was a quadratic regression between the yield and GDD before winter. According to the regression equation, the optimum GDD range with high yield of semi-winterness and weak springness wheats was 750-770 and 570-590°C d, respectively; (iii) under the optimum GDD condition, the foliar age on the main stem of semi-winterness and weak springness wheats was 7.67–7.91 and 6.36–6.86 leaves, respectively, calculated by the linear regression equation between foliar age and GDD before winter; (iv) both semi-winterness and weak springness wheats were in the double ridge stage of spike differentiation under the condition of the optimum GDD range, and at this time, the foliar age on the main stem of semi-winterness and weak springness wheats was about 7.80 and 6.07 leaves, respectively, which was consistent with the results calculated by the liner regression equation. Therefore, we could consider that the sowing date is appropriate if the foliar age is about 7.8 and 6.3 leaves for semi-winterness and weak springness wheats, respectively. According to the results of this study, choosing semi-winterness wheat and planting 7-10 d earlier would improve yield and natural resource utilization in NCP.
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DOI:10.1016/j.cj.2016.07.002URL [本文引用: 1]
Variation in weather conditions during grain filling has substantial effects on maize kernel weight (KW). The objective of this work was to characterize variation in KW with sowing date-associated weather conditions and examine the relationship between KW, grain filling parameters, and weather factors. Maize was sown on eight sowing dates (SD) at 15–20-day intervals from mid-March to mid-July during 2012 and 2013 in the North China Plain. With sowing date delay, KW increased initially and later declined, and the greatest KW was obtained at SD6 in both years. The increased KW at SD6 was attributed mainly to kernel growth rate (Gmean), and effective grain-filling period (P). Variations in temperature and radiation were the primary factors that influenced KW and grain-filling parameters. When the effective cumulative temperature (AT) and radiation (Ra) during grain filling were 950°C and 1005.4MJm612, respectively, P and KW were greatest. High temperatures (daily maximum temperature [Tmax]>30.2°C) during grain filling under early sowing conditions, or low temperatures (daily minimum temperature [Tmin]<20.7°C) under late sowing conditions combined with high diurnal temperature range (Tmax-min>7.1°C) decreased kernel growth rate and ultimately final KW. When sowing was performed from May 25 through June 27, higher KW and yield of maize were obtained. We conclude that variations in environmental conditions (temperature and radiation) during grain filling markedly affect growth rate and duration of grain filling and eventually affect kernel weight and yield of maize.
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DOI:10.1007/s11104-011-1020-7URL [本文引用: 1]
Background and Aims Root system development is affected by soil conditions. The effects of bulk density, water content and penetration resistance on root development processes were investigated in...
DOI:10.1016/j.still.2004.02.006URL [本文引用: 1]
The philosophy toward tillage throughout the last century in Hungary can be characterized as a fight against extreme climatic and economic situations. The ungarian reasonable tillage approach that was promoted by Cserhti at the end of the 1800s was aimed at reducing tillage without increasing the risk of crop failure in arable fields. Recently, new tillage trends and systems have been introduced because of the rise in energy prices and because of the need to cut production costs, conserve soil and water resources and protect the environment. In Hungarian relation, the rationalized plowing, loosening and mulching systems are counted to the new tillage solutions. There are new steps in the sowing methods too, such as seedbed preparation and plant in one pass, till and plant, mulch-till and plant and direct drilling, which are environment capable, throughout improving soil condition and avoiding the environment harms. The applicability of various soil conservation tillage methods is currently being tested in research projects and discussed in workshops throughout the country. In this paper, soil quality problems such as compaction, trends in soil tillage, and factors affecting soil quality or condition as well as improvement and maintenance are summarized. The data show that annual disking and plowing causes subsoil compaction at the depth of tillage within 3 years and that the compacted layer expanded both in surface and deeper layers after the 5th year. Soil quality deterioration by tillage-pans was improved by subsoiling and maintained by direct drilling and planting soil-loosening catch crops. Within a loam and a sandy loam soil there were close correlations between earthworm activity and soil quality. Earthworm numbers increased on undisturbed but noncompacted soils and soils that included stubble residues remaining on the surface, but did not increase on soils that were deteriorated by tillage-pans or left bare by the absence of mulch. Our goal for the new millennium, is to use only enough tillage to create and maintain harmony between soil conservation, soil quality and crop production.
DOI:10.1016/S0167-1987(01)00167-2URL [本文引用: 1]
A study was conducted in the North China Plain during the summer maize growth season 1997, using field and laboratory measurement techniques, in order to evaluate the impacts of different tillage practices (conventional tillage (CT), no-tillage (NT) and subsoiling tillage(ST)) on the top soil physical and hydraulic properties. ST caused an important reduction in bulk density in the top 40 cm of the soil profile, a significant increase of the volume of the larger pores (>50 渭m diameter) and a significant decrease of the volume of the smaller pores (<10 m diameter). This resulted in an improvement of water transmission at high water content and in a decrease of water retention capacity at low water content. Water infiltration into the subsoiled soil was improved owing to greater macroporosity. Small differences were observed between CT and NT practices. Changes of topsoil properties induced by tillage practices were found to be subject to significant temporal variations, particularly for bulk density, infiltrability and field saturated hydraulic conductivity.
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DOI:10.1371/journal.pone.0129231URLPMID:26098548 [本文引用: 3]
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.
DOI:10.1371/journal.pone.0174952URLPMID:5383055 [本文引用: 2]
Subsoiling is an important management practice for improving maize yield, especially for maize planted at high plant density. However, the affected physiological processes have yet to be specifically identified. In this study, field experiments with two soil tillage (CK: no-tillage, SS: subsoiling) and three planting densities (low: 45000 plants ha611, medium: 67500plants ha611, and high: 90000 plants ha611) were conducted from 2010 to 2012 at Xinxiang, Henan province. Yield, canopy function, and root system were investigated to determine the associated physiological processes for improving maize production affected by soil tillage and plant density. Subsoiling significantly increased the grain yield of the low-, medium-, and high-planting densities by 6.21%, 8.92%, and 10.09%, respectively. Yield increase in the SS plots was mainly attributed to greater post-anthesis DMA and improved grain filling compared to CK plots. Greater green leaf area, leaf net photosynthetic rate, FV/Fmand ΦPSII in the SS plots were mainly contributed to enhanced dry matter production post-anthesis. This is mainly because subsoiling increased density of root dry weight in deep soil and root bleeding sap amount due to decreased the bulk density of the 0–30 cm soil profile layer. Density of root dry weight at 10–50 cm depth with SS increased by 40.68%, 32.17%, and 20.14% at low, medium, and high planting densities compared to CK, respectively, while the root bleeding sap amount increased by 17.41%, 15.82%, and 20.91%. These results indicate that subsoiling could change the root distribution and improve soil layer environment for root growth, thus maintaining a higher canopy photosynthetic capacity post-anthesis and in turn promoting DMA and yield, particularly at higher planting densities.
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DOI:10.1016/j.still.2008.01.007URL [本文引用: 1]
Soil tillage practices can affect soil hydraulic properties and processes dynamically in space and time with consequent and coupled effects on chemical movement and plant growth. This literature review addresses the quantitative effects of soil tillage and associated management (e.g., crop residues) on the temporal and spatial variability of soil hydraulic properties. Our review includes incidental management effects, such as soil compaction, and natural sources of variability, such as topography. Despite limited research on space ime predictions, many studies have addressed management effects on soil hydraulic properties and processes relevant to improved understanding of the sources of variability and their interactions in space and time. Whether examined explicitly or implicitly, the literature includes studies of interactions between treatments, such as tillage and residue management. No-tillage (NT) treatments have been compared with various tillage practices under a range of conditions with mixed results. The trend, if any, is for NT to increase macropore connectivity while generating inconsistent responses in total porosity and soil bulk density compared with conventional tillage practices. This corresponds to a general increase in ponded or near-zero tension infiltration rates and saturated hydraulic conductivities. Similarly, controlled equipment traffic may have significant effects on soil compaction and related hydraulic properties on some soils, but on others, landscape and temporal variability overwhelm wheel-track effects. Spatial and temporal variability often overshadows specific management effects, and several authors have recognized this in their analyses and interpretations. Differences in temporal variability depend on spatial locations between rows, within fields at different landscape positions, and between sites with different climates and dominant soil types. Most tillage practices have pronounced effects on soil hydraulic properties immediately following tillage application, but these effects can diminish rapidly. Long-term effects on the order of a decade or more can appear less pronounced and are sometimes impossible to distinguish from natural and unaccounted management-induced variability. New standards for experimental classification are essential for isolating and subsequently generalizing space ime responses. Accordingly, enhanced methods of field measurement and data collection combined with explicit spatio-temporal modeling and parameter estimation should provide quantitative predictions of soil hydraulic behavior due to tillage and related agricultural management.
DOI:10.2135/cropsci2016.07.0623URL [本文引用: 1]
Abstract Conventional fertilization with most N applied before or during early maize (Zea mays L.) growth stages can negatively affect production if soil N is insufficient after silking. Here, drip irrigation with a split application of N (drip fertigation) was evaluated to determine whether the effect on yield and N use efficiency (NUE) differs with cropping practice. Compared with conventional fertilization, drip fertigation increased yield by 13 and 14% at a low planting density under a low N rate (L) and by 15% at a high planting density under a high N rate (H) in 2012 and 2013, respectively. Yield increases under drip fertigation were attributed to 18 and 17% increases in postsilking dry matter (DM) accumulation under L, and 12 and 10% increases in presilking DM accumulation, and 17 and 16% increases in postsilking DM accumulation under H in 2012 and 2013, respectively. Increased postsilking N accumulation under drip fertigation, promoted by greater root length and soil mineral N after silking, maintained increased leaf area index (LAI) and DM accumulation rate to improve postsilking DM accumulation under L. Greater N accumulation under drip fertigation from the 12-leaf stage to silking and after silking promoted greater LAI and DM accumulation rate to increase pre- and postsilking DM accumulation under H. Because of greater grain yield and N uptake and less water consumption, drip irrigation improved NUE and irrigation water use efficiency. Drip fertigation can effectively improving maize grain yield and NUE resulting from improved DM accumulation with increased early-season N uptake.
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DOI:10.1073/pnas.1101419108URLPMID:21444818 [本文引用: 3]
China and other rapidly developing economies face the dual challenge of substantially increasing yields of cereal grains while at the same time reducing the very substantial environmental impacts of intensive agriculture. We used a model-driven integrated soil-crop system management approach to develop a maize production system that achieved mean maize yields of 13.0 t ha6301 on 66 on-farm experimental plots—nearly twice the yield of current farmers' practices—with no increase in N fertilizer use. Such integrated soil-crop system management systems represent a priority for agricultural research and implementation, especially in rapidly growing economies.
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DOI:10.1016/S1002-0160(12)60016-2URL [本文引用: 2]
Many recently developed N management strategies have been extremely successful in improving N use efficiency. However, attempts to further increase grain yields have had limited success. Field experiments were conducted in 2007 and 2008 at four sites to evaluate the effect of an in-season root-zone N management strategy on maize (Zea mays L.). According to the in-season root-zone N management, the optimal N rate (ONR) was determined by subtracting measured soil mineral N (NH+461N and NO613-N) in the root zone from N target values. Other treatments included a control without N fertilization, 70% of ONR, 130% of ONR, and recommended N rate (RNR) by agronomists in China that have been shown to approach maize yield potentials. Although apparent N recovery for the ONR treatment was significantly higher than that under RNR in 2007, grain yield declined from 13.3 to 11.0 Mg ha611 because of an underestimation of N uptake. In 2008, N target values were adjusted to match crop uptake, and N fertilization rates were reduced from 450 kg N ha611 for RNR to 225 to 265 kg N ha611 for ONR. High maize yields were maintained at 12.6 to 13.5 Mg ha611, which were twice the yield from typical farmers' practice. As a result, apparent N recovery increased from 29% to 66%, and estimated N losses decreased significantly for the ONR treatment compared to the RNR treatment. In conclusion, the in-season root-zone N management approach was able to achieve high yields, high NUE and low N losses.
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Slow/controlled release fertilizers(SRFs/CRFs) have been paid more attentions by the researchersin recent years.In this paper,the application effects and methods,types,current problem and development prospect of SRFs/CRFsboth at home and abroad were reviewed.The production principles and processes of ureaformaldehyde slow release fertilizers were introduced;and It is suggested that the urea-formaldehyde slow release fertilizers show great development to ease energy and environment pressure.
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In agronomic management, photothermic resources will play an increasingly important role in boosting crop yields to meet growing demands. This study explored photothermic resource use efficiency and predicted the highest theoretical yield of four crop types (maize, rice, ratoon rice and wheat) in the high-yielding regions of the Northeast plain, Huai Hai Lyrics valley and Yangtze River valley o...
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