刘月娥^**, 吕天放^**, 赵久然^,*, 王荣焕^,*, 徐田军^*, 陈传永^*, 张译天^*, 王元东^*, 刘秀芝^*北京市农林科学院玉米研究中心 / 玉米DNA指纹及分子育种北京市重点实验室, 北京100097

Silking duration characteristics in different maize hybrids and its response to sowing date

LIU Yue-E^**, LYU Tian-Fang^**, ZHAO Jiu-Ran^,*, WANG Rong-Huan^,*, XU Tian-Jun^*, CHEN Chuan-Yong^*, ZHANG Yi-Tian^*, WANG Yuan-Dong^*, LIU Xiu-Zhi^*Maize Research Center, Beijing Academy of Agriculture & Forestry Sciences / Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing 100097, China

通讯作者: *赵久然, E-mail: maizezhao@126.com,Tel: 010-51503936 *王荣焕, E-mail: ronghuanwang@126.com,Tel: 010-51503703

第一联系人: 刘月娥, E-mail: lye0520@163.com; 吕天放, E-mail: 314565358@qq.com^** 同等贡献(Contributed equally to this work)
收稿日期:2018-04-18接受日期:2018-10-8网络出版日期:2018-11-05

基金资助:

本研究由国家重点研发计划项目.2016YFD0300106 本研究由国家重点研发计划项目.2017YFD0101104 国家自然科学基金项目.31601247 国家现代农业产业技术体系专项.CARS-02-11 北京市农林科学院青年科研基金项目.QNJJ201728 北京市农林科学院院级科技创新团队建设项目资助.JNKYT201603

Received:2018-04-18Accepted:2018-10-8Online:2018-11-05

Fund supported:

This study was supported by the National Key Research and Development Program of China.2016YFD0300106 This study was supported by the National Key Research and Development Program of China.2017YFD0101104 the National Natural Science Foundation of China.31601247 the China Agriculture Research System.CARS-02-11 the Youth Research Fund of the Beijing Academy of Agriculture and Forestry Sciences.QNJJ201728 and the Innovative Team Construction Project of BAAFS.JNKYT201603

摘要
吐丝期是决定玉米产量的关键时期, 研究其相关特性, 对玉米生产意义重大。为准确分析不同玉米品种吐丝特性的差异及其对播期的响应, 于2014年和2015年设置了3个玉米主推品种(郑单958、先玉335和京科968)的3个播期处理(早播: 4月10日, 中播: 5月10日, 晚播: 6月10日), 分析了各个处理间吐丝持续期的差异以及吐丝持续期与雌穗穗长变异及产量构成因素的关系。结果表明: (1)群体吐丝持续期在品种间存在显著差异, 表现为先玉335 (9.12 d) >郑单958 (8.94 d) >京科968 (7.68 d)。随时间推进, 玉米每天吐丝的比例与天数为先升高后降低的二次函数关系, 每天最大吐丝比例为先玉335 (16.51%)<郑单958 (17.07%)<京科968 (19.98%)。京科968较郑单958和先玉335呈现吐丝集中, 每天吐丝比例较高、吐丝持续期短的特点; (2)吐丝持续期在不同播期间差异显著, 郑单958、先玉335和京科968不同播期间的吐丝持续期变幅分别为8.10~9.55 d、7.54~10.53 d和6.65~8.66 d, 郑单958的吐丝持续期在不同播期间最稳定(CV=6.57%), 其次为京科968 (CV=9.40%), 先玉335的吐丝持续期在不同播期间的变化最不稳定(CV=11.68%); (3)吐丝持续期与雌穗穗长的变异系数呈显著正相关, 与产量和穗粒数呈显著负相关, 与千粒重不相关。播期对玉米吐丝持续期具有显著的调控作用。随吐丝持续期增加, 玉米雌穗穗长的变异系数显著增大, 群体果穗的整齐度降低, 穗粒数显著减少, 是玉米产量显著降低的主要原因。
关键词： 玉米;品种;吐丝持续期;播期;产量

Abstract
Silking is an important growth stage and has important effects on maize (Zea mays L.) yield. The research of silking characteristics plays a fundamental role in maize productivity. To examine the silking characteristics difference of different maize hybrids and its responses to sowing date, we conducted an experiment with three sowing date (4/10, 5/10, 6/10) treatments using the most widely cultivated maize hybrids of Zhengdan 958 (ZD958), Xianyu 335 (XY335), and Jingke 968 (JK968). The silking duration difference between different hybrids and the relationship of silking duration with ear length variation and yield components were analyzed. The significant differences were found in silking durations with an order of XY335 (9.12 d) > ZD958 (8.94 d) > JK968 (7.68 d). The silking ratio per day was well correlated with days to silking (P < 0.05), A non-linear positive relationship existed between silking ratio per day (y) and days to silking (x). The highest silking ratio per day showed an order of XY335 (16.51%) < ZD958 (17.07%) < JK968 (19.98%). Significant differences of silking duration were found between different sowing date treatments. The silking durations of ZD958, XY335, and JK968 in different sowing date treatment ranged from 8.10 d to 9.55 d (CV = 6.57%), from 7.54 d to 10.53 d (CV = 9.40%), from 6.55 d to 8.66 d (CV = 11.68%), respectively. Silking duration significantly and positively correlated the coefficient of variation of ear length, and negatively correlated with yield and kernel number per ear. No significant correlation was found between silking duration and 1000-kernel weight. Sowing date has significant effects on silking duration. With increasing silking duration , the coefficient of variation of ear length is increased significantly, the uniformity of ear length and kernel number per ear are decreased, resulting in maize yield decrease significantly.
Keywords：maize;hybrid;silking duration;sowing date;yield


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本文引用格式
刘月娥, 吕天放, 赵久然, 王荣焕, 徐田军, 陈传永, 张译天, 王元东, 刘秀芝. 不同玉米杂交品种吐丝持续期特性及其对播期的响应[J]. 作物学报, 2019, 45(2): 310-315. doi:10.3724/SP.J.1006.2019.83034
LIU Yue-E, LYU Tian-Fang, ZHAO Jiu-Ran, WANG Rong-Huan, XU Tian-Jun, CHEN Chuan-Yong, ZHANG Yi-Tian, WANG Yuan-Dong, LIU Xiu-Zhi. Silking duration characteristics in different maize hybrids and its response to sowing date[J]. Acta Agronomica Sinica, 2019, 45(2): 310-315. doi:10.3724/SP.J.1006.2019.83034


吐丝期是决定玉米产量的关键时期^[1,2,3], 吐丝期遭受到高温、干旱、弱光等逆境胁迫对玉米产量影响巨大^{[3,4,5,6,7,8]}。玉米开花吐丝的相关特性在玉米生产中起非常重要的作用, 因此对于开花吐丝特性例如玉米抽雄、散粉、吐丝的时间以及雌雄穗开花间隔等^{[9,10,11,12,13,14,15,16,17]}的遗传基础前人做了很多研究。花粉脱落的时间、吐丝持续期和花丝的接受力更能反映玉米散粉和吐丝的同步性, 从而直接影响穗粒数和玉米产量^[18]。玉米籽粒的形成受花丝的接受力、花粉粒活力和吐丝、散粉一致性的影响, 玉米较低的籽粒形成能力直接导致玉米产量的降低。而延迟吐丝对玉米籽粒形成的影响远大于延迟授粉, 并且吐丝和散粉的一致性在不同玉米品种间存在显著差异^[19]。Borrás等^[1]研究发现玉米吐丝的进程与开花前后的气象条件密切相关, 吐丝时间的早晚取决于雌穗的干物质积累, 与吐丝前后干物质的生长速率密切相关。李金才等^[20]通过对玉米不同花位间花丝的生长动态及影响花丝发育的气象因素研究发现日均温度和光照对玉米的吐丝影响显著。

综上, 前人关于玉米吐丝期的关注和研究大多针对吐丝期逆境对玉米生长发育的影响^[3,5,8], 对于吐丝特性的研究较多针对玉米至抽雄、散粉、吐丝的时间以及玉米雌雄穗开花间隔等^{[9,10,11,12,13,14,15,16,17,18]}, 而关于玉米吐丝持续期的研究相对较少, 尤其是玉米杂交种吐丝持续期的研究鲜见报道。不同玉米杂交种吐丝持续期的特性, 播期对不同玉米品种吐丝持续期的调控效果以及对玉米产量的影响研究对实现玉米高产、稳产具有重要意义, 并可为育种家选育高产稳产玉米新品种提供重要参考指标。

1 材料与方法

1.1 试验地点

北京市农林科学院玉米研究中心北京市昌平区试验基地位于东经116.39°, 北纬40.17°, 海拔50 m, 属于温带大陆性季风气候, 年均总降水量500~600 mm, 年均温11.1°C。土壤pH 7.1, 含全氮0.77 g kg^-1、有效磷9.71 mg kg^-1、有效钾82.3 mg kg^-1。

1.2 试验设计

本试验以我国玉米生产上三大主推品种郑单958 (ZD958)、先玉335 (XY335)和京科968 (JK968)为试验材料, 设置2014年5月10日和6月10日2个播期, 2015年4月10日、5月10日和6月10日3个播期。以播种日期为主区, 玉米品种为副区, 种植密度60,000株 hm^-2, 播深5 cm, 田间管理同当地大田生产。每小区10行, 行距60 cm, 行长10 m, 面积60 m²。观测不同玉米品种的吐丝特性, 调查产量相关性状等。

1.3 测定项目与方法

1.3.1 吐丝持续期 自小区内第一棵玉米吐丝起至小区内最后一株玉米吐丝结束。

1.3.2 收获测产 在小区内任意选取3行, 连续收获20穗测产, 记录穗长、穗粗、秃尖长、穗行数、行粒数、千粒重; 取10穗立刻脱粒, 80℃下烘干至恒重, 记录干重, 测量籽粒含水量, 计算理论产量, 按标准水分14%折算。

1.3.3 吐丝持续期的计算 用每天的吐丝比例(y)和天数(x)进行一元二次方程拟合(y = ax²+bx+c)。设y = 0, 对方程求解(x₁和x₂), x₂与x₁之差即为玉米吐丝持续的天数。

1.3.4 玉米雌穗穗长的变异 测量收获测产的玉米果穗长, 通过所有的穗长求得变异系数, 即为玉米雌穗穗长的变异。

1.4 数据统计

用Microsoft Excel 2007软件计算数据和作图; 用SAS 9.1软件统计分析。

2 结果与分析

2.1 不同玉米品种的抽雄吐丝特点

随着时间的推进, 玉米每天的吐丝比例(y)与天数(x)呈先升高后降低的二次函数关系, 拟合度均达显著水平, 且不同品种间存在显著差异(图1和表1)。吐丝持续期表现为先玉335>郑单958>京科968, 分别为9.12 d、8.94 d和7.68 d, 郑单958和先玉335之间差异不显著, 但均显著高于京科968。不同玉米品种达到最大吐丝比例的时间为郑单958>京科968>先玉335, 分别为5.17 d、4.71 d和4.70 d。每天最大吐丝比例表现为京科968>郑单958>先玉335, 分别为19.98%、17.07%和16.51%。

图1

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图1不同玉米品种每天吐丝比例的变化

^**和^*表示在0.01和0.05水平显著相关。
Fig. 1Changes of maize silking ratio in different maize hybrids

^** and ^* mean significant at the 0.01 and 0.05 probability levels, respectively.


Table 1
表1
表1不同玉米品种的吐丝持续期
Table 1Silking duration changes of different hybrids

品种 Hybrid	2014			2015			平均值 Average (d)	变异系数 Coefficient of variation (%)
	May 10	June 10		April 10	May 10	June 10
郑单958 Zhengdan 958	9.23	8.10		9.24	9.55	8.59	8.94 a	6.57
先玉335 Xianyu 335	7.54	9.02		9.25	10.53	9.25	9.12 a	11.68
京科968 Jingke 968	6.65	7.54		7.67	8.66	7.89	7.68 b	9.40

Values within a column followed by different letters are significantly different at P < 0.05.
同一参数中标注不同字母的值表示不同处理间在P < 0.05水平上差异显著。

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2014年和2015年5月10日和6月10日2个播期的抽雄吐丝间隔变化不大, 3个品种(郑单958、先玉335和京科968) 4月10日和5月10日2个播期的抽雄吐丝间隔为1~2 d; 在4月10日播期, 品种间抽雄吐丝间隔变化较大, 郑单958和京科968的抽雄吐丝间隔时间为4 d, 先玉335的抽雄吐丝间隔为2 d (表2)。

Table 2
表2
表2不同玉米品种抽雄吐丝日期及抽雄吐丝间隔
Table 2Tasseling date, silking date and interval between tasseling and silking change of different hybrids

年份 Year	播期 Sowing date (month/day)	品种 Cultivar	抽雄日期 Tasseling date (month/day)	吐丝日期 Silking date (month/day)	抽雄吐丝间隔 Interval between tasseling and silking (d)
2014	5/10	郑单958 Zhengdan 958	7/8	7/9	1
		先玉335 Xianyu 335	7/10	7/8	2
		京科968 Jingke 968	7/10	7/11	1
	6/10	郑单958 Zhengdan 958	8/3	8/5	2
		先玉335 Xianyu 335	8/4	8/5	1
		京科968 Jingke 968	8/6	8/8	2
2015	4/10	郑单958 Zhengdan 958	6/22	6/26	4
		先玉335 Xianyu 335	6/23	6/25	2
		京科968 Jingke 968	6/23	6/27	4
	5/10	郑单958 Zhengdan 958	7/10	7/12	2
		先玉335 Xianyu 335	7/9	7/11	2
		京科968 Jingke 968	7/12	7/14	2
	6/10	郑单958 Zhengdan 958	8/4	8/6	2
		先玉335 Xianyu 335	8/5	8/6	1
		京科968 Jingke 968	8/3	8/5	2

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2.2 播期对玉米吐丝影响

玉米吐丝持续期在不同播期间差异显著。郑单958、先玉335和京科968不同播期间(4月10日、5月10日和6月10日)的吐丝持续期变幅分别为8.10~9.55 d、7.54~10.53 d和6.65~8.66 d, 变异系数分别为6.57%、11.68%和9.40% (图1和表1)。随着播期的变化, 不同品种的最大吐丝比例和达到最大吐丝株数的时间均显著变化, 在不同播期间郑单958的最大吐丝比例和达到最大吐丝比例的时间分别为15.49%~18.54%和4.59 d~5.65 d, 变异系数分别为7.30%和8.40%; 不同播期间, 先玉335和京科968的最大吐丝比例分别为14.70%~20.42%和18.68%~22.97%, 变异系数分别为13.71%和8.72%; 达到最大吐丝比例的时间分别为3.71~5.42 d和4.28~5.16 d, 变异系数分别为13.95%和7.01%。年份对玉米品种达到最大吐丝时间和最大吐丝比例均存在显著影响, 2014年不同播期间玉米品种达到最大吐丝比例和最大吐丝比例时间的变异显著高于2015年, 2014年不同播期间玉米达到最大吐丝比例时间和最大吐丝比例的变异系数分别为14.06%和13.68%, 分别比2015年(6.40%和5.29%)高119.75%和158.45%。

2.3 吐丝持续期与雌穗穗长的变异和产量及其构成因素的关系

玉米吐丝持续期与玉米雌穗穗长的变异系数显著相关(图2)。随着吐丝持续期的增加, 玉米雌穗穗长的变异系数显著增大, 群体果穗的整齐度降低。4月10日、5月10日和6月10日3个播期条件下均表现相同趋势, 吐丝持续期每增加1 d, 雌穗穗长的变异系数分别增加0.32%、0.86%和0.60%。

图2

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图2玉米吐丝持续期与雌穗穗长变异的相关分析

^** 和^*表示在0.01和0.05水平显著相关。
Fig. 2Correlation relationship between maize silking duration and coefficient of variation of ear length

^** and ^* mean significant at the 0.01 and 0.05 probability levels, respectively.


随着吐丝持续期的延长, 5月10日和6月10日2个播期的玉米产量显著降低, 吐丝持续期每增加1 d, 玉米产量分别降低1060.5 kg hm^-2和3618.2 kg hm^-2。4月10日播期条件下, 随着玉米吐丝持续期的延长, 玉米产量有所降低, 但未达到显著水平(图3)。

图3

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图3玉米吐丝持续期与产量构成因素的相关分析

^**和^*表示在0.01和0.05水平显著相关。
Fig. 3Correlation between maize silking duration and yield components

^** and ^* mean significant at the 0.01 and 0.05 probability levels, respectively.


随着吐丝持续期的延长, 5月10日和6月10日2个播期条件下参试玉米品种的穗粒数显著降低, 吐丝持续期每增加1 d, 穗粒数分别降低25.36粒和94.70粒。4月10日播期条件下, 随着玉米吐丝持续期的延长, 穗粒数降低, 但未达到显著水平; 4月10日、5月10日和6月10日3个播期条件下, 玉米吐丝持续期与千粒重之间相关不显著 (图3)。随着吐丝持续期的延长, 穗粒数的显著降低是玉米产量降低的主要原因。

3 讨论

3.1 不同玉米杂交种的吐丝特点

本研究发现, 不同玉米品种间的吐丝持续期存在显著差异, 表现为先玉335>郑单958>京科968, 郑单958和先玉335之间吐丝持续期差异不显著, 但都显著高于京科968。说明, 与郑单958和先玉335相比, 京科968具有吐丝持续期较短的特点。

分析不同玉米品种的吐丝特点以及吐丝持续期不同的原因发现, 随着时间的推进, 玉米每天的吐丝比例(y)与天数(x)呈先升高后降低的二次函数关系, 郑单958到达每天最大吐丝比例的时间最晚, 为5.17 d, 最大吐丝比例为17.07%; 先玉335到达最大吐丝比例的时间为4.70 d, 每天最大吐丝比例最小, 为16.51%; 京科968到达每天最大吐丝比例的时间为4.71 d, 最大吐丝比例最高, 为19.98%。京科968较快达到最大吐丝株数和每天较高的吐丝比例是其吐丝持续期短的主要原因。

3.2 吐丝持续期与果穗及产量相关性状的关系

进一步分析玉米吐丝持续期与雌穗穗长变异的关系, 发现品种的吐丝持续期越长, 雌穗穗长的变异系数越大, 群体果穗的整齐度降低。究其原因, 可能与该阶段玉米雌穗的干物质积累有关。前人研究发现玉米吐丝时间的早晚取决于雌穗的干物质积累, 与吐丝前后干物质的生长速率密切相关^[1]。

吐丝持续期与产量及产量构成因素的关系说明吐丝持续期的变化对玉米产量产生了一定影响, 随着吐丝持续期的延长, 5月10日和6月10日2个播期条件下的玉米产量及穗粒数显著降低。4月10日播期条件下, 随着玉米吐丝持续期的延长, 玉米产量和穗粒数也降低, 但未达到显著水平; 而所有播期处理(4月10日、5月10日和6月10日)的吐丝持续期与千粒重不相关。说明玉米吐丝持续期延长后, 穗粒数显著减少是玉米产量显著降低的主要原因。分析原因可能是较长的吐丝持续期影响花丝的接受力, 从而影响籽粒形成^[19], 进而影响穗粒数和产量^[18]。吐丝持续期较短、雌穗集中吐丝授粉质量较高, 是京科968产量较郑单958和先玉335高的原因之一。

3.3 播期对玉米品种吐丝持续期的影响

玉米吐丝持续期的长短在不同播期间差异显著, 郑单958、先玉335和京科968不同播期间(4月10日、5月10日和6月10日)的吐丝持续期变幅分别为8.10~9.55 d、7.54~10.53 d和6.65~8.66 d。分析原因可能与气象因素有关, 随着播期的变化, 玉米生长发育期间的气象因素发生显著变化, 而玉米吐丝的进程与开花前后的气象条件密切相关^[1], 日均温度和光照对玉米吐丝具有显著影响^[20]。而不同玉米品种对播期的响应也不同, 郑单958的吐丝持续期随着播期的变化变异系数为6.57%, 先玉335和京科968分别为11.68%和9.40%, 虽然郑单958的吐丝持续期较长, 但对播期的变化不敏感; 京科968属于吐丝持续期最短, 但对播期反应中等的品种; 先玉335的吐丝持续期最长、对播期的变化反应最敏感; 具体影响不同玉米品种吐丝持续期的气象因素还有待进一步研究。

The authors have declared that no competing interests exist.

作者已声明无竞争性利益关系。

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[1] Borrás L, Westgate M E, Astini J P, Echarte L E . Coupling time to silking with plant growth rate in maize
Field Crops Res, 2007,102:73-85.
DOI:10.1016/j.fcr.2007.02.003URL [本文引用: 4]
In maize ( Zea mays L.), progress towards pistillate flower maturity (silking) is highly dependent upon the environmental conditions around flowering. Under conditions that inhibit plant growth, female flower development is delayed relative to that of the male flowers resulting in an increase in the anthesis ilking interval (ASI). Although variation in ASI has been extensively documented, its relationship to plant growth is not well understood. Therefore, we developed a conceptual basis and experimental approach for quantifying and analyzing the process of female flowering in maize in response to variation in plant growth rate during the flowering period. Time to silking depends on biomass accumulation at the ear level, as silking for each plant is a developmental stage dependent upon ear expansion growth. Because plants within a maize canopy differ in their growth rate around flowering, plants with rapid growth rate reach silking earlier than the ones growing at lower rates. This is a consequence of differential accumulation of ear biomass around anthesis. As such, quantifying canopy plant-to-plant variability in ear growth around anthesis is a critical component for resolving time to silking for the population of plants. Moreover, plant biomass partitioning to the developing ear (ear growth rate/total plant growth rate around flowering) differs depending on the plant growth rate, and among genotypes. In order to resume this complexity, we developed a simple plant biomass growth framework to quantify time to silking for maize plant populations that takes into account plant-to-plant growth variability and partitioning of biomass to the developing ear around flowering.

[2] Gabaldon L C, Webber H, Otegui M E, Slafer G A, Ordonez R A, Gaiser T, Lorite I J, Ruiz R M, Ewert F . Modelling the impact of heat stress on maize yield formation
Field Crops Res, 2016,198:226-237.
DOI:10.1016/j.fcr.2016.08.013URL [本文引用: 1]
The frequency and intensity of extreme high temperature events are expected to increase with climate change. Higher temperatures near anthesis have a large negative effect on maize (Zea mays, L.) grain yield. While crop growth models are commonly used to assess climate change impacts on maize and other crops, it is only recently that they have accounted for such heat stress effects, despite limited field data availability for model evaluation. There is also increasing awareness but limited testing of the importance of canopy temperature as compared to air temperature for heat stress impact simulations. In this study, four independent irrigated field trials with controlled heating imposed using polyethylene shelters were used to develop and evaluate a heat stress response function in the crop modeling framework SIMPLACE, in which the Lintul5 crop model was combined with a canopy temperature model. A dataset from Argentina with the temperate hybrid Nidera AX 842 MG (RM 119) was used to develop a yield reduction function based on accumulated hourly stress thermal time above a critical temperature of 34°C. A second dataset from Spain with a FAO 700 cultivar was used to evaluate the model with daily weather inputs in two sets of simulations. The first was used to calibrate SIMPLACE for conditions with no heat stress, and the second was used to evaluate SIMPLACE under conditions of heat stress using the reduction factor obtained with the Argentine dataset. Both sets of simulations were conducted twice; with the heat stress function alternatively driven with air and simulated canopy temperature. Grain yield simulated under heat stress conditions improved when canopy temperature was used instead of air temperature (RMSE equal to 175 and 309gm612, respectively). For the irrigated and high radiative conditions, raising the critical threshold temperature for heat stress to 39°C improved yield simulation using air temperature (RMSE: 221gm612) without the need to simulate canopy temperature (RMSE: 175gm612). However, this approach of adjusting thresholds is only likely to work in environments where climatic variables and the level of soil water deficit are constant, such as irrigated conditions and are not appropriate for rainfed production conditions.

[3] Liu G, Hou P, Xie R, Ming B, Wang K, Liu W, Yang Y, Li S . Canopy characteristics of high-yield maize with yield potential of 22.5 Mg ha ^-1
Field Crops Res, 2017,213:221-230.
DOI:10.1016/j.fcr.2017.08.011URL [本文引用: 3]
Over three continuous years (2013–2015) of high-yield experiments, maize hybrid DH618 was grown at densities of 12.0 and 13.502×0210 4 plants ha 611 at Qitai Farm (89°34′E, 44°12′N), Xinjiang, China, and broke the record for the highest yield in China. Therefore, it is considered to have plant characteristics that approach those of the ideotype. In 2014 and 2015, various canopy characteristics were measured. On average, the dry matter gain of hybrid DH618 was 20.0, and 36.502Mg02ha 611 during post-silking and at maturity, a transfer rate from vegetation organs of 8.7%, and harvest index of 0.54. On average, it had a leaf area index of 7.53 at silking, a leaf area of 3.9902×0210 3 and 1.9002×0210 3 02cm 2 above and below the ear, and a spatial density of leaf area of 0.17 and 0.0802cm 2 02cm 613 above and below ear, respectively. The average light transmissions were 3.7% and 1.1% at the ear and bottom respectively, and the attenuation coefficient was 0.63. The plant height and ear height were about 287 and 11302cm. The average leaf orientation values were 51.9 and 49.2 above and below ear, respectively. These results will be of great significance for ideotype breeding programs and maize yield improving.

[4] Paponov I A, Sambo P, Erley G S, Presterl T, Geiger H H, Engels C . Kernel set in maize genotypes differing in nitrogen use efficiency in response to resource availability around flowering
Plant Soil, 2005,272:101-110.
DOI:10.1007/s11104-004-4210-8URL [本文引用: 1]

[5] Jia S F, Li C F . Effects of shading at different stages after anthesis on maize grain weight and quality at cytology level
J Integr Agric, 2011,10:58-69.
DOI:10.1016/S1671-2927(11)60307-6URL [本文引用: 2]
The objective of the current study is to investigate the effects of different stages of shading after anthesis on grain weight and quality of maize at cytology level. The shading experiments were conducted in the field from 2005 to 2006, with a common maize cultivar (TY2) as the experimental material. Plants were given stress using horizontal shading net and the light intensity was reduced by 55%. Field-grown maize plants were shaded at 1-14 d (SI), 15-28 d (S2), and 29-42 d (S3) after pollination, respectively. Control plants (SO) were grown under natural light. Grain weight, quality, endosperm cell proliferation, cob sugar content, and grain pedicel vascular bundle cross section area were measured. The ultrastructural changes of endosperm cells and endosperm transfer cells were observed after pollination. The result indicated that the grain weight, starch content, endosperm cell number, and volume were declined after shading. On the contrary, the proportion of embryo and endosperm, protein content, and fat content in grain increased. Shading treatments significantly delayed the development of the starch granules and remarkably reduced the endosperm filling status. Among the three treatments, the number of the grain endosperm was the least under shading stress at 1-14 d after pollination. However, the volume of starch granules and the substantiation of endosperm under shading treatment at 15-28 d after pollination were the worst. Compared with the control (natural sunlight without shading), the soluble sugar of maize cob increased significantly, while there was no obvious change in vascular structure of small cluster stalk. The number of protein body in maize endosperm was influenced markedly by low light at different stages after pollination. Low light decreased the volume of the grain endosperm transfer and the cell wall extensions of the basal transfer cells became thinner and shorter under shading treatment than those of the control. Furthermore, the degree of connection and the capacity of the nutrient transport were decreased and the mitochondrion number of the transfer cell was reduced after shading. The change in grain quality after shading was observed due to increase in the proportion of embryo and endosperm. The morphology and functions in endosperm transfer cell and the shortage of energy restricted the nutrient transport greatly with shading at different stages, suggesting that an impeded flux may be one of the important reasons for the reduction of maize grain weight of maize grain at later growth stage under low light condition.

[6] 张仁和, 郭东伟, 张兴华, 海东, 刘建超, 李凤艳, 郝引川, 薛吉全 . 吐丝期干旱胁迫对玉米生理特性和物质生产的影响
作物学报, 2012,38:1884-1890.
DOI:10.3724/SP.J.1006.2012.01884URL [本文引用: 1]
以玉米品种郑单958（抗旱性强）和陕单902（抗旱性弱）为材料,采用抗旱池栽控水试验,研究了2个品种叶片光合特性、保护酶活性以及干物质转运对吐丝期干旱胁迫的响应。结果表明,在吐丝期干旱胁迫下2个品种产量分别降低39.10%和44.87%;叶片净光合速率（Pn）和气孔导度（Gs）显著下降,胞间CO2浓度（Ci）先升后降。PSII最大光化学效率（Fv/Fm）、实际量子产额（ΦPSII）、光化学猝灭（qP）降低,非光化学猝灭（qN）升高;抗氧化酶（SOD、POD和CAT）活性先升高后降低,而丙二醛（MDA）含量一直升高。吐丝期干旱胁迫增加了花前营养器官贮藏同化物转运量（率）及其对籽粒转运的贡献率;但郑单958受干旱影响程度小于陕单902。抗旱品种郑单958具高抗氧化酶活性清除活性氧,使得膜脂过氧化程度轻,维持较高的光化学效率,延长叶片光合功能期,促进花前营养器官贮藏同化物转运量对籽粒的贡献率。这可能是其在干旱胁迫下仍能获得较高产量的重要原因之一。
Zhang R H, Guo D W, Zhang X H, Lu H D, Liu J C, Li F Y, Hao Y C, Xue J Q . Effect of drought stress on physiological characteristics and dry matter production in maize silking stage
Acta Agron Sin, 2012,38:1884-1890 (in Chinese with English abstract).
DOI:10.3724/SP.J.1006.2012.01884URL [本文引用: 1]
以玉米品种郑单958（抗旱性强）和陕单902（抗旱性弱）为材料,采用抗旱池栽控水试验,研究了2个品种叶片光合特性、保护酶活性以及干物质转运对吐丝期干旱胁迫的响应。结果表明,在吐丝期干旱胁迫下2个品种产量分别降低39.10%和44.87%;叶片净光合速率（Pn）和气孔导度（Gs）显著下降,胞间CO2浓度（Ci）先升后降。PSII最大光化学效率（Fv/Fm）、实际量子产额（ΦPSII）、光化学猝灭（qP）降低,非光化学猝灭（qN）升高;抗氧化酶（SOD、POD和CAT）活性先升高后降低,而丙二醛（MDA）含量一直升高。吐丝期干旱胁迫增加了花前营养器官贮藏同化物转运量（率）及其对籽粒转运的贡献率;但郑单958受干旱影响程度小于陕单902。抗旱品种郑单958具高抗氧化酶活性清除活性氧,使得膜脂过氧化程度轻,维持较高的光化学效率,延长叶片光合功能期,促进花前营养器官贮藏同化物转运量对籽粒的贡献率。这可能是其在干旱胁迫下仍能获得较高产量的重要原因之一。

[7] 陈春梅, 高聚林, 苏治军, 于晓芳, 胡树平, 赵晓亮 . 玉米自交系吐丝期叶片光合参数与其耐旱性的关系
作物学报, 2014,40:1667-1676.
DOI:10.3724/SP.J.1006.2014.01667URL [本文引用: 1]
, , , , /, , and SPAD had a , WUE, /, , and SPAD significantly correlated with drought resistance coefficient at , WUE and SPAD directly contributed to drought resistance coefficient, while / and contributed indirectly. Thirty-two maize inbred lines were classified into three groups based on different drought resistance, group 1 with the highest drought resistance contained eight inbred lines (H201, WUE, /, , SPAD, and drought resistance coefficient can be used as drought resistance evaluation indexes established for the three groups of maize inbred lines. Regression relationship was between , WUE, /, , SPAD, and drought resistance coefficient at silking stage, and the threshold values were confirmed.
Chen C M, Gao J L, Su Z J, Yu X F, Hu S P, Zhao X L . Relationship between leaf photosynthetic parameters and drought resistance at silking stage in maize inbred lines
Acta Agron Sin, 2014,40:1667-1676 (in Chinese with English abstract).
DOI:10.3724/SP.J.1006.2014.01667URL [本文引用: 1]
, , , , /, , and SPAD had a , WUE, /, , and SPAD significantly correlated with drought resistance coefficient at , WUE and SPAD directly contributed to drought resistance coefficient, while / and contributed indirectly. Thirty-two maize inbred lines were classified into three groups based on different drought resistance, group 1 with the highest drought resistance contained eight inbred lines (H201, WUE, /, , SPAD, and drought resistance coefficient can be used as drought resistance evaluation indexes established for the three groups of maize inbred lines. Regression relationship was between , WUE, /, , SPAD, and drought resistance coefficient at silking stage, and the threshold values were confirmed.

[8] Ren B, Cui H, Camberato J J, Dong S, Liu P, Zhao B, Zhang J . Effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of summer maize
Naturwissenschaften, 2016,103:67.
DOI:10.1007/s00114-016-1392-xURLPMID:27437706 [本文引用: 2]
A field experiment was conducted to study the effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of two summer maize hybrids Denghai605 (DH605) and Zhengdan958...

[9] Beavis W D, Smith O S, Grant D, Fincher R R . Identification of quantitative trait loci using a small sample of top crossed and F₄ progeny from maize
Crop Sci, 1994,34:882-896.
DOI:10.2135/cropsci1994.0011183X003400040010xURL [本文引用: 2]

[10] Veldboom L R, Lee M . Molecular-marker-facilitated studies of morphological traits in maize. II: Determination of QTLs for grain yield and yield components
Theor Appl Genet, 1994,89:451-458.
DOI:10.1007/BF00225380URLPMID:24177894 [本文引用: 2]
Genetic factors controlling quantitative inheritance of grain yield and its components have not previously been investigated by using replicated lines of an elite maize ( Zea mays L.) population. The present study was conducted to identify quantitative trait loci (QTLs) associated with grain yield and grain-yield components by using restriction fragment length polymorphism (RFLP) markers. A population of 150 random F 2 3 lines was derived from the single cross of inbreds Mo17 and H99, which are considered to belong to the Lancaster heterotic group. Trait values were measured in a replicated trial near Ames, Iowa, in 1989. QTLs were located on a linkage map constructed with one morphological and 103 RFLP loci. QTLs were found for grain yield and all yield components. Partial dominance to overdominance was the primary mode of gene action. Only one QTL, accounting for 35% of the phenotypic variation, was identified for grain yield. Two to six QTLs were identified for the other traits. Several regions with pleiotropic or linked effects on several of the yield components were detected.

[11] Berke T G, Rocheford T R . Quantitative trait loci for flowering, plant and ear height, and kernel traits in maize
Crop Sci, 1995,35:1542-1549.
DOI:10.2135/cropsci1995.0011183X003500060004xURL [本文引用: 2]
The inheritance of quantitative traits is not well understood. A study was conducted to determine the number and chromosomal locations of quantitative trait loci (QTL) controlling male anthesis date ; plant and ear height ; kernel weight ; and kernel protein, oil, and starch concentration in maize (Zea mays L.). Two hundred S

[12] Agrama H A S, Moussa M E . Mapping QTLs in breeding for drought tolerance in maize (Zea mays L.).
Euphytica, 1996,91:89-97.
DOI:10.1007/BF00035278URL [本文引用: 2]
Grain yield in the maize ( Zea mays L) plant is sensitive to drought in the period three weeks either side of flowering. Maize is well-adapted to the use of restriction fragment length polymorphisms (RFLPs) to identify a tight linkage between gene(s) controlling the quantitative trait and a molecular marker. We have determined the chromosomal locations of quantitative trait loci (QTLs) affecting grain yield under drought, anthesis-silking interval, and number of ears per plant. The F 3 families derived from the cross SD34(tolerant) SD35 (intolerant) were evaluated for these traits in a two replicated experiment. RFLP analysis of the maize genome included non-radioactive DNA-DNA hybridization detection using chemiluminescence. To identify QTLs underlying tolerance to drought, the mean phenotypic performances of F 3 families were compared based on genotypic classification at each of 70 RFLP marker loci. The genetic linkage map assembled from these markers was in good agreement with previously published maps. The phenotypic correlations between yield and other traits were highly significant. In the combined analyses, genomic regions significantly affecting tolerance to drought were found on chromosomes 1,3,5,6, and 8. For yield, a total of 50% of the phenotypic variance could be explained by five putative QTLs. Different types of gene action were found for the putative QTLs for the three traits.

[13] Kozumplik V, Pejic I, Senior L, Pavlina R, Graham G I, Stuber C W . Use of molecular markers for QTL detection in segregating maize populations derived from exotic germplasm
Maydica, 1996,41:211-217.
[本文引用: 2]

[14] Ribaut J, Hoisington D, Deutsch J A, Jiang C Z, Gonzalez de Leon D . Identification of quantitative trait loci under drought conditions in tropical maize: 1. Flowering parameters and the anthesis-silking interval
Theor Appl Genet, 1996,92:905-914.
DOI:10.1007/BF00221905URLPMID:24166558 [本文引用: 2]
Drought is an important climatic phenomenon which, after soil infertility, ranks as the second most severe limitation to maize production in developing countries. When drought stress occurs just before or during the flowering period, a delay in silking is observed, resulting in an increase in the length of the anthesis-silking interval (ASI) and in a decrease in grain yield. Selection for reduced ASI in tropical open-pollinated varieties has been shown to be correlated with improved yields under drought stress. Since efficient selection for drought tolerance requires carefully managed experimental conditions, molecular markers were used to identify the genomic segments responsible for the expression of ASI, with the final aim of developing marker-assisted selection (MAS) strategies. An F 2 population of 234 individuals was genotyped at 142 loci and F 3 families were evaluated in the field under several water regimes for male flowering (MFLW), male sterility (STER), female flowering (FFLW) and ASI. The genetic variance of ASI increased as a function of the stress intensity, and the broad-sense heritabilites of MFLW, FFLW and ASI were high under stress conditions, being 86%, 82% and 78%, respectively. Putative quantitative trait loci (QTLs) involved in the expression of MFLW and/or FFLW under drought were detected on chromosomes 1, 2, 4, 5, 8, 9 and 10, accounting for around 48% of the phenotypic variance for both traits. For ASI, six putative QTLs were identified under drought on chromosomes 1, 2, 5, 6, 8 and 10, and together accounted for approximately 47% of the phenotypic variance. Under water stress conditions, four QTLs were common for the expression of MFLW and FFLW, one for the expression of ASI and MFLW, and four for the expression of ASI and FFLW. The number of common QTLs for two traits was related to the level of linear correlation between these two traits. Segregation for ASI was found to be transgressive with the drought-susceptible parent contributing alleles for reduced ASI (4 days) at two QTL positions. Alleles contributed by the resistant line at the other four QTLs were responsible for a 7-day reduction of ASI. These four QTLs represented around 9% of the linkage map, and were stable over years and stress levels. It is argued that MAS based on ASI QTLs should be a powerful tool for improving drought tolerance of tropical maize inbred lines.

[15] Veldboom L R, Lee M . Genetic mapping of qunatitative trait loci in maize in stress and nonstress environments: II. Plant height and flowering
Crop Sci, 1996,36:1320-1327.
DOI:10.2135/cropsci1996.0011183X003600050041xURL [本文引用: 2]
The utility of restriction fragment length polymorphisms (RFLPs) in mapping quantitative trait loci (QTL) has been established in elite maize (Zea mays L.) populations, but the ability to consistently detect QTL in diverse environments has not been assessed. QTL mapping studies conducted in diverse environments could be a means of locating genes which respond to stress conditions and coyuld provide further understanding of some types of genotype x environment interaction. Our objectives were to investigate the ability to detect QTL for flowering and plant stature traits in two diverse environments and to assess the genetic relationship of QTL for correlated traits. A single-cross of elite inbreds Mo17 and H99 was used to produce a population of 150 F

[16] Rebai A, Blanchard P, Perret D, Vincourt P . Mapping quantitative trait loci controlling silking date in a diallel cross among four lines of maize
Theor Appl Genet, 1997,95:451-459.
DOI:10.1007/s001220050582URL [本文引用: 2]
We describe and apply an interval mapping method for quantitative trait locus (QTL) detection using F-3 and testcross progenies derived from F-2 populations obtained from a diallel cross among four elite lines of maize. Linear model-based procedures were used for the test and estimation of putative QTL effects together with genetic interactions including epistasis. We mapped QTL associated with silking date and explored their genetic effects. Ten QTL were detected, and these explained more than 40% of the phenotypic variance. Most of these QTL had consistent and stable effects among genetic backgrounds and did not show significant epistasis. QTL-by-environment interaction was important for four QTL and was essentially due to changes in magnitude of allelic effects. These results show the efficiency of our method in several genetic situations as well as the power of the diallel design in detecting QTL simultaneously over several populations.

[17] Khairallah M, Bohn M, Jiang C Z, Deutsch J A, Jewell D C, Mihm J A, Melchinger A E, Gonzalez de Leon D, Hoisington D . Molecular mapping of QTL for southwestern corn borer resistance, plant height and flowering in tropical maize
Plant Breed, 1998,117:309-318.
DOI:10.1111/j.1439-0523.1998.tb01947.xURL [本文引用: 2]
Development of multiple insect resistance in tropical maize represents a major effort of the maize breeding programme at CIMMYT. Resistance to the southwestern corn borer (SWCB) is polygenically controlled with primarily additive gene action. Our main objective was to identify quantitative trait loci (QTL) involved in resistance to SWCB. Other objectives were to detect QTL in the same population for plant height, female flowering, and the anthesis-silking interval (ASI). A population of 472 F 2 individuals derived from a cross between the susceptible line Ki3 and the resistant inbred CML139, was restriction fragment length polymorphism (RFLP) genotyped using 110 maize probes. F 3 families were rated for leaf-feeding damage after artificial infestation at one location in three consecutive years. Height and flowering were measured in protected trials in two locations. QTL analyses were conducted using joint composite interval mapping. Seven QTL on chromosomes 3, 5, 6, 8, and 9 explained 30% of the phenotypic variance ( 2 p ) for SWCB damage. Most QTL alleles conferring resistance were contributed from CML139. QTL showed dominance, partial dominance and additive gene action. Eleven QTL dispersed across the genome were determined to affect plant height and explained 43% of 2 p . Four of these were in close proximity to loci with qualitative effects on plant height. Thirteen QTL (50% of sigma; 2 p ) were identified for days to female flowering and nine (30% of 2 p ) for ASI. Our results, along with those from other mapping studies at CIMMYT, are allowing us to formulate marker-assisted selection schemes to complement the breeding efforts for such complex traits as borer resistance.

[18] Xie H, Ding D, Cui Z, Wu X, Hu Y, Liu Z, Li Y, Tang J . Genetic analysis of the related traits of flowering and silk for hybrid seed production in maize
Genes Genomics, 2010,32:55-61.
DOI:10.1007/s13258-010-0801-3URL [本文引用: 3]
In the field, asynchrony of flowering and silk for male and female plants always occurs under different abiotic stresses, and reduces yield in the seed industry. Under stress conditions, a female parent with a short duration of silk emergence and a long time of silk receptivity can decrease the risk of the asynchrony for flowering and silking in the process of hybrid seed production. For dissecting the genetic basis of the related traits of flowering and silk in maize, a set of recombinant inbred lines (RIL) was evaluated at three different environments. Correlation analysis showed that anthesis silk interval (ASI) had a significant positive relationship with day to silk (DTS) and duration of silk emergence (DSE). Silk receptivity (SR) had a significant negative correlation to DTS, DSE, and ASI. This implied that the female parent with a long DTS, DSE, and ASI could easy lose its SR, and required synchrony of pollen shedding for the male parent in the field. A total of sixteen different QTLs were identified for the seven traits of flowering and silking traits, including three QTLs for day to tassel (DTT), two for day to pollen (DTP), two for duration of pollen shedding (DPS), three for SR, two for DTS, two for DSE, and two for ASI. The QTLs detected for the related traits of flowering and silk could select ideal traits for male and female parents to raise the yield in the seed industry under certain stress conditions.

[19] Wang Y, Cui Y, Zhang L, Li J, Liu J, Wang R . Effects of syncrhonization between silk receptivity and pollen grain vigor on kernel sets of corn (Zea mays L.).
Front Agric China, 2007,1:271-275.
DOI:10.1007/s11703-007-0046-3URL [本文引用: 2]
Kernel sets in corn were affected by silk receptivity, pollen grain vigor, and the synchronization of silking and pollen shedding. Grain yield decrement was often caused by poor kernel set ability under field conditions. This study was conducted with two corn hybrids—Yedan 12 and Yedan 19—in both field and laboratory to observe silk receptivity, pollen vigor, synchronization of silking and pollen, and their effects on the kernel sets. The results showed that silk receptivity could be maintained over a relatively longer period of time after silks emerged, but both kernel set percentage and kernel weight decreased as silks aged when pollination occurred. Pollen grains that shed earlier had higher TTC-dehydrogenase activity, higher germination percentage, more rapid pollen tube growth rate, and higher percentage of kernel sets and kernel weight than those that shed later. The effect of delayed silking on kernel set ability was more significant compared with delayed pollen. Synchronization of silking and pollen shedding showed different characters in different hybrids: “partial overlapped” for Yedan 12 and “overlapped” for Yedan 19.

[20] 李金才, 董海荣, 崔彦宏 . 不同花位间玉米花丝生长发育动态的研究
河北农业大学学报, 2003,26(2):1-4.
DOI:10.3969/j.issn.1000-1573.2003.02.001URL [本文引用: 2]
以中熟夏玉米品种掖单12为试验材料,对不同花位间花丝的生长动态进行了研究。结果表明:花丝的发生首先开始于果穗中下部,其次是基部和中部,顶部花丝出现最晚。花丝的伸长过程呈典型的"S"型曲线,生长速率为单峰曲线。吐丝后第3天生长速率最大。中下部花丝最先抽出苞叶,其次是基部和中部,顶部最晚。衰亡过程也开始于中下部,基部和中部其次,顶部最晚。花丝的生长发育和花丝的数量与花丝生长发育期间的温度、光照条件密切相关。日平均温度较高、光照好的年份花丝发育早、数量多;温度低、光照时间短的年份则花丝发育迟缓,最顶部花丝甚至不发育,花丝数量减少。
Li J C, Dong H R, Cui Y H . Study on the dynamics of growth and development of maize silks in different flower positions
J Agric Univ Hebei, 2003,26(2):1-4 (in Chinese with English abstract).
DOI:10.3969/j.issn.1000-1573.2003.02.001URL [本文引用: 2]
以中熟夏玉米品种掖单12为试验材料,对不同花位间花丝的生长动态进行了研究。结果表明:花丝的发生首先开始于果穗中下部,其次是基部和中部,顶部花丝出现最晚。花丝的伸长过程呈典型的"S"型曲线,生长速率为单峰曲线。吐丝后第3天生长速率最大。中下部花丝最先抽出苞叶,其次是基部和中部,顶部最晚。衰亡过程也开始于中下部,基部和中部其次,顶部最晚。花丝的生长发育和花丝的数量与花丝生长发育期间的温度、光照条件密切相关。日平均温度较高、光照好的年份花丝发育早、数量多;温度低、光照时间短的年份则花丝发育迟缓,最顶部花丝甚至不发育,花丝数量减少。