柏延文^,1, 张宏军², 朱亚利¹, 郑学慧¹, 杨梅¹, 李从锋³, 张仁和^,11西北农林科技大学农学院,陕西杨凌 712100
²陕西省种子工作总站,西安 710003
³中国农业科学研究院作物科学研究所,北京 100081

Responses of Canopy Radiation and Nitrogen Distribution, Leaf Senescence and Radiation Use Efficiency on Increased Planting Density of Different Variety Types of Maize

BAI YanWen^,1, ZHANG HongJun², ZHU YaLi¹, ZHENG XueHui¹, YANG Mei¹, LI CongFeng³, ZHANG RenHe^,11College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi
²Shaanxi Seed Work Station, Xi'an 710003
³Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081

通讯作者: 张仁和,E-mail： zhangrenhe1975@163.com

责任编辑: 杨鑫浩
收稿日期:2020-04-9接受日期:2020-06-11网络出版日期:2020-08-01

基金资助:

国家重点研发计划.2017YFD0300304 陕西省重点研发计划.2017ZDCXL-NY-02-02 陕西省技术创新引导专项.2019TG-002

Received:2020-04-9Accepted:2020-06-11Online:2020-08-01
作者简介 About authors
柏延文,E-mail： yanwbai1993@163.com。









摘要
【目的】探究增密对不同株型玉米冠层光氮分布、衰老特征、及其对光能利用及产量的影响,为陕西春玉米高产高效栽培提供支撑。【方法】于2017—2018年以陕单609（紧凑型）和陕单8806（平展型）为试验材料,设置4个种植密度（45 000、60 000、75 000和90 000株/hm²）,测定了冠层光氮分布、叶片衰老、物质生产、光能利用及产量构成等指标。【结果】陕单609和陕单8806分别在90 000株/hm²（13 824 kg·hm^-2）和60 000株/hm²（9 566 kg·hm^-2）达到了最高产量,与45 000株/hm²相比,90 000株/hm²下陕单609和陕单8806的穗粒数（17.8%和30.1%）和百粒重（15.2%和19.6%）均降低。同一密度下,2个品种的冠层光能截获率和叶片氮素浓度表现为上层>中层>下层,随着密度的增加,2个品种冠层上部光能截获率和叶片氮素浓度不断增加,中层和下层的光能截获率和叶片氮素浓度不断下降,当密度增至90 000株/hm²时,陕单8806冠层中部和下部的光能截获率分别较陕单609低8.8%和70.6%,且陕单609中层和下层的叶片氮素浓度较陕单8806高16.0%和40.5%。当密度从45 000株/hm²增至90 000株/hm²,陕单609和陕单8806成熟期相对绿叶面积分别降低36.4%和63.3%,叶片平均衰老速率分别增加40.2%和34.6%,冠层不同层次叶片衰老启动的时间顺序为下层>上层>中层,与陕单8806相比,90 000株/hm²下陕单609生育后期冠层中上部的绿叶面积较高,且下层维持较高的绿叶面积。随种植密度的增加,吐丝前后的氮素吸收量和氮收获指数显著增加,当密度增至90 000株/hm²时,陕单609吐丝前后的氮素吸收量、氮收获指数分别较陕单8806高23.5%、43.9%、12.7%。增密后生物产量、收获指数、冠层光能截获量和光能利用率显著增加,密度增至90 000株/hm²时,陕单609的生物产量、冠层的光合有效辐射、光能利用率和收获指数分别较陕单8806高26.1%、10.2%、9.1%和14.8%。【结论】与陕单8806比,紧凑玉米陕单609密植下较好协同优化冠层光氮空间分布,增加了群体花后中下部光能截获量,延缓群体冠层花后中下层叶片衰老,促进群体花后干物质和氮素积累,获得更高的籽粒产量和光能利用率。
关键词： 春玉米;株型;种植密度;冠层衰老;光氮分布;光能利用率

Abstract
【Objective】The objective of this experiment was to study the effects of planting density on canopy senescence, radiation use efficiency and yield of different plant types maize, so as to provide technical support for cultivation of high yield and high efficiency of spring maize in northern Shaanxi. 【Method】 In 2017 and 2018, the field experiments were conducted by using two maize hybrids, including Shaandan 609 (compact) and Shaandan 8806 (flat), with four planting density treatments, including 45 000, 60 000, 75 000 and 90 000 plants/hm². Canopy light and nitrogen distribution, leaf senescence, nitrogen accumulation, dry matter production, radiation use efficiency and yield components were determined. 【Result】 Shaandan609 and Shaandan8806 reached the highest grain yield at 90 000 plants/hm² (13 824 kg·hm^-2) and 60 000 plants/hm² (9 566 kg·hm^-2), respectively. Compared with 45 000 plants/hm², the average kernels per ear (17.8% and 30.1%) and 100-kernels weight (15.2% and 19.6%) of Shaandan609 and Shaandan 8806 both reduced under 90 000 plants/hm². The canopy light interception and leaf nitrogen concentration of the two varieties showed: the upper layer>the middle layer>the lower layer. With the increase of planting density, the fraction of the photosynthetically active radiation interception (FIPAR) and leaf nitrogen concentration increased at upper layer, but decreased at the mid and lower layer. When the density increased to 90 000 plants/hm², the FIPAR at middle and upper canopy and the lower canopy of Shaandan 8806 were 8.8% and 70.6% lower than Shaandan 609, respectively, and the leaf nitrogen concentration at middle and upper canopy layer and lower canopy of Shaandan 609 were 16.0% and 40.5% higher than Shaandan 8806. When density increased from 45 000 plants/hm² to 90 000 plants/hm², the relative green leaf area at maturity (RGLA_m) decreased by 36.4% and 63.3%, respectively, while the mean rate of decrease in RGLA (V_m) increased by 40.2% and 34.6%, respectively. The sequence of date of onset of leaf senescence (T_s) was as follows: the lower layer>the upper layer>the middle layer. Compared with Shaandan 8806, the green leaf area was higher in the middle and upper layer of Shaandan 609, and maintained a higher green leaf area at the lower layer during the later growth stage under 90 000 plants/hm². With the increasing of planting density, the nitrogen uptake during the pre-silking (Npre) and post-silking (Npost), and nitrogen harvest index (NHI) increased significantly. When the density increased to 90 000 plants/hm², Npre, Npost and NHI of Shaandan 609 were 23.5%, 43.9% and 12.7% higher than Shaandan 8806, respectively. The biomass yield (BM), intercept photosynthetically active radiation (IPAR) and radiation use efficiency (RUE) increased significantly when improved plant density. When the density increased to 90 000 plants/hm², the BM, IPAR, RUE and HI of Shaandan 609 were 26.1%, 10.2%, 9.1% and 14.8% higher than Shaandan 8806.【Conclusion】Compared with Shaandan 8806, the compact maize Shaandan 609 could improve the spatial distribution of light and nitrogen at the middle and upper layer under high density, increased the light intercept at the middle and lower canopy, delayed leaf senescence at the mid and lower canopy, and promoted the dry matter accumulation after silking, so a higher grain yield and RUE were obtained.
Keywords：spring maize;plant type;plant density;canopy senescence;radiation and nitrogen distribution;radiation use efficiency


PDF (1373KB)元数据多维度评价相关文章导出EndNote|Ris|Bibtex收藏本文
本文引用格式
柏延文, 张宏军, 朱亚利, 郑学慧, 杨梅, 李从锋, 张仁和. 不同株型玉米冠层光氮分布、衰老特征及光能利用对增密的响应[J]. 中国农业科学, 2020, 53(15): 3059-3070 doi:10.3864/j.issn.0578-1752.2020.15.007
BAI YanWen, ZHANG HongJun, ZHU YaLi, ZHENG XueHui, YANG Mei, LI CongFeng, ZHANG RenHe. Responses of Canopy Radiation and Nitrogen Distribution, Leaf Senescence and Radiation Use Efficiency on Increased Planting Density of Different Variety Types of Maize[J]. Scientia Acricultura Sinica, 2020, 53(15): 3059-3070 doi:10.3864/j.issn.0578-1752.2020.15.007

0 引言

【研究意义】玉米是陕西省第一大粮食作物,合理增密是陕西玉米高产高效的方向^[1,2],而玉米最佳种植密度随着气候、栽培技术和品种特性而变化^[3,4]。随着密度的增加,冠层内光能截获量减少,削弱了中下部叶片的光照条件,易造成冠层叶片早衰,直接影响了玉米植株的光合性能,从而限制了籽粒库的建成^[5,6]。紧凑耐密型玉米是影响种植密度和产量的关键因子,其植株中上部叶片直立,对群体密度增加有一个适度的调节,有利于平衡避荫下群体冠层内光的分布,使其更加合理,充分利用不同层次的光能^[7,8],对促进陕西玉米产量和光能利用率的提高具有重要意义。【前人研究进展】前人研究发现,玉米密植高产是增加生物量的结果,归功于增加群体叶面积指数,截获更多光能的潜力^[9,10]。优化冠层光分布能显著增加群体光合作用和产量^[11,12]。如TIAN等^[13]将UPA2的大刍草等位基因回交导入到农大108双亲中,获得的改良农大108叶夹角减小,提高了株型紧凑程度,改善了冠层内光的分布,实现了密植增产。HUANG等^[14]在玉米不同生育期喷施化学调控剂调节叶片大小,优化冠层光分布延缓叶片衰老,提高了玉米密植的生产潜力。提高密植环境中冠层光合作用,更多叶片氮素含量应分布在冠层的中上部以适应高的光照强度,因为叶片氮分布显著影响冠层光合作用^[15]。研究指出,生长在冠层顶部接受更多光照的叶片含氮量高于在冠层下部遮阴环境下生长的叶片^[16]。此外,氮素的积累和转运是引起玉米叶片发生衰老的重要生理过程^[17],延缓叶片衰老可延长叶片光合活性,而这也能增加植株的氮素吸收能力,从而提高了冠层截获光合有效辐射转化为干物质的效率,即光能利用率^[18,19,20]。光能利用率可用来评价不同栽培条件下作物产量的形成^[21]。【本研究切入点】前人针对种植密度对玉米冠层结构、光合作用、氮素物质积累与转运、产量的影响进行了大量研究^{[21,22,23,24,25]},但有关不同株型玉米品种冠层不同层次光氮分布、叶片衰老特征对增密的响应,及其对光能利用和产量影响的研究报道较少。【拟解决的关键问题】本研究选择2种不同株型玉米品种,设置4个种植密度,研究其对玉米群体冠层光氮分布、叶片衰老动态、光能利用及产量的影响,以期为陕北灌溉春玉米密植高产高效栽培提供理论依据。

1 材料与方法

1.1 试验设计

试验在陕西省榆林市西北农林科技大学玉米试验示范站（37°48′N、109°11′E,海拔1 808 m）进行。该区属温带半干旱大陆性季风气候,无霜期短,蒸发量1 900 mm,年均气温8℃,年平均降水量400 mm左右,年日照时数2 600—2 900 h,是我国日照高值区之一,图1为2017—2018年玉米生育期气象数据。试验站土壤类型为砂壤土,耕层0—20 cm土壤含有机质6.76 g·kg^-1、速效氮42.75 mg·kg^-1、速效磷16.98 mg·kg^-1、速效钾99.77 mg·kg^-1。

图1

新窗口打开|下载原图ZIP|生成PPT
图12017-2018年玉米生育期内太阳辐射、温度、降雨量以及空气相对湿度的变化

Fig. 1Solar radiation, temperature, rainfall and daily relative humidity changes during the maize growth period in 2017 and 2018



供试材料为陕单609（紧凑型）和陕单8806（平展型）。试验采用二因素裂区设计,密度为主区,品种为裂区,密度处理为45 000、60 000、75 000、90 000株/hm²。小区行长为5 m,宽为3.6 m。等行距种植,行间距为0.6 m,每个小区内种6行,共设4个重复。2017和2018年分别在4月23日和4月20日人工播种,于10月5日和9月30日收获。其他田间管理水平与当地农田一致。

1.2 测定项目与方法

1.2.1 叶片衰老变化特征 于玉米吐丝期,从各试验小区选取生育进程一致,生长均匀的代表性植株20株,做好标记。吐丝后每隔7 d,在每个小区取3株同一天吐丝的标记植株测量绿叶面积,冠层叶片分为上层（穗上第二叶至冠层顶部）、中间层（穗三叶）和下层（穗下第二叶至冠层基部）,叶片超过一半变黄被定义为衰老叶片,利用长宽系数法测定吐丝期至生理成熟期的冠层绿叶面积,叶面积指数（LAI）=单位群体叶面积/单位土地叶面积。

用曲线方程y=ae^b-cx/(1+e^b-cx)描述叶片衰老变化过程,其中y为某一时刻的相对绿叶面积（RGLA,%）,x为吐丝后的天数,参数a为RGLA的理论初始值,b与叶片衰老的启动有关,c与叶片衰老的速度有关。成熟期相对绿叶面积RGLA_m（%）=成熟期绿叶面积/吐丝期绿叶面积;叶片衰老启动时间（T_s）指相对绿叶面积达到95%时的初始日期;平均衰老速率（V_m）=（吐丝期相对绿叶面积-成熟期相对绿叶面积）/时间间隔;相对绿叶面积最大衰减速率V_max=c/4;出现最大绿叶衰减速率的时间T_max=b/c^[26]。

1.2.2 积温 积温的单位是℃d,其定义如下：

$Td=\sum_{1}^{n}(Ta-Tb)$

式中,Ta是日平均气温,用每日最高和最低温度的平均值计算,Tb是生长发育的基础温度,n是计算中温度观测的总天数。积温用于预测植物的生长发育^[27]。

1.2.3 植株干物质累积量及氮含量测定 分别于玉米吐丝期（VT）、灌浆期（R3）和成熟期（R6）,从各试验小区选取3株生长一致的健壮植株,取地上部分,将其分为上层（穗上第二叶至冠层顶部）、中间层（穗三叶）和下层（穗下第二叶至冠层基部）,取叶和茎（含叶鞘）、穗轴、苞叶、籽粒部分装入纸袋,在105℃下杀青30 min,80℃下烘干至恒重后称重,用粉碎机将样品磨成粉末,使用H₂SO₄-H₂O₂消煮,采用凯氏定氮法测定植物样品全氮浓度,计算氮素积累量^[28]。

1.2.4 光能截获率和光能利用率 于玉米吐丝期（VT）、灌浆期（R3）和成熟期（R6）,天气晴朗的上午11：00—13：00,使用LP-80冠层仪在各小区内进行冠层光合有效辐射（PAR）的测定,垂直于行向,在株间和行间上层（穗上第二叶至冠层顶部）、中层（穗三叶）和下层（穗下第二叶至冠层基部）3个高度,分别测量各冠层高度的PAR（mol·m^-2·s^-1）,每个小区重复测量3次,计算冠层不同部位光能截获率（FIPAR）：

透光率=I_t/I₀;

光能截获率（FIPAR）=1-透光率-反射率。

式中,I_t是在不同冠层高度的辐射强度,I₀是冠层顶部的辐射强度。

利用测定的叶面积指数（LAI）、冠层的有效辐射PAR（mol·m^-2·s^-1）、采样日期之间的总辐射截获积累量Q_a（MJ·m^-2）和干物质积累（DMA）,计算消光系数（K）、冠层截获光合有效辐射量（IPAR,MJ·m^-2）和光能利用率（RUE,g·MJ^-1）^[29]：

K=(-1/LAI)×ln(I_t/I₀);

IPAR=Q_a×[1-exp(-K×LAI)];

RUE=DMA/IPAR。

1.2.5产量及产量构成 成熟期统计每个小区的倒伏株数、空秆株数,收获中间2行计产并调查穗行数、行粒数、百粒重等性状,计产时籽粒含水量统一折算成14%。

1.3 数据处理与统计分析

本文2017—2018年的相关数据分析中,变化规律相一致时用2年的平均值表述。采用Excel 2010软件进行数据处理,SAS 8.0软件对各指标进行统计分析,制图软件为Origin 2017。

2 结果

2.1 增密对不同株型玉米产量及其构成的影响

图2所示,随着密度的增加,2个玉米品种的穗粒数和百粒重均呈降低趋势,产量则显著增加。密度增至60 000株/hm²时,陕单8806的产量（9 566 kg·hm^-2）最高,产量较45 000株/hm²增加19.7%,而陕单609在90 000株/hm²达到产量的峰值（13 824 kg·hm^-2）,产量较45 000株/hm²增加26.9%。从产量构成来看,当种植密度从45 000株/hm²增至90 000株/hm²时,陕单609和陕单8806的平均穗粒数分别下降17.8%（107粒）和30.1%（163粒）,平均百粒重分别降低15.2%（5.6 g）和19.6%（6.1 g）。在4个种植密度下,陕单609平均百粒重和穗粒数较陕单8806高出16.1%（5.4 g）和14.3%（78.9粒）,但在60 000株/hm²下,陕单609和陕单8806的产量分别为11 613.5 kg·hm^-2和9 517.5 kg·hm^-2,陕单609的穗粒数和百粒重分别较陕单8806高出10.1%、12.9%。当密度达到90 000株/hm²时,陕单609的穗粒数（23.4%）和百粒重（19.5%）均高于陕单8806。因此,提高产量主要是增加了株数的同时,维持较高的粒数和粒重。

图2

新窗口打开|下载原图ZIP|生成PPT
图2种植密度对不同株型玉米产量构成的影响

同一品种不同字母表示种植密度处理间差异达到显著水平（P<0.05）。下同
Fig. 2Effects of planting density on yield components of different plant types of maize

Different letters represent significantly different among planting densities in same hybrid at P<0.05. The same as below

2.2 增密对不同株型玉米冠层光分布的影响

如图3所示,2年各处理冠层不同部位光能截获率的变化趋势存在显著的差异（P<0.05）,就冠层整体而言,随着种植密度的增加,陕单609的光能截获率呈增加趋势,而陕单8806则先升高后降低,陕单609冠层总的光能截获率较陕单8806高8.7%。随种植密度的增加,冠层上部光能截获率呈增加趋势,中下层光能截获率则不断降低,陕单609冠层上层、中层和下层的光能截获率分别较陕单8806低12.6%、高36.5%、高51.8%。当密度为60 000株/hm²时,陕单8806整体光能截获率达到最大值,其冠层上层、中层和下层的光能截获率分别较陕单609高21.1%、低30.4%、低41.8%,说明陕单8806中上层的受光条件较好,但冠层下部的光能截获较陕单609差。当密度增至90 000株/hm²时,陕单8806冠层上层、中层和下层的光能截获率分别较陕单609高3.9%、低49.6%、低70.6%。高密度下陕单609冠层上层较低的光能截获率在一定程度上优化了冠层中下部的光能截获,改善了中下层叶片的光能捕获,使冠层内的光分布更合理。

图3

新窗口打开|下载原图ZIP|生成PPT
图3种植密度对不同株型玉米光能截获率的影响（灌浆期）

Fig. 3Effects of planting density on the fraction of the photosynthetically active radiation for different plant-types maize (grain filling stage)

2.3 增密对不同株型玉米冠层氮分布的影响

从图4中可知,2个品种同一密度下冠层叶片氮素浓度表现为上层>中层>下层,随着种植密度的增加,冠层上部叶片氮素浓度显著升高,中层和下层的叶片氮素浓度显著降低。品种间,陕单609冠层上层、中层和下层的叶片氮素浓度分别较陕单8806高5.8%、22.2%和27.6%。当密度增至60 000株/hm²时,陕单609和陕单8806冠层上部的叶片氮素浓度分别高于中层（12.9%、24.0%）和下层（26.3%、36.2%）,且陕单609中层和下层的叶片氮素浓度较陕单8806高11.7%和20.2%,密度达到90 000株/hm²时,陕单609和陕单8806冠层上部的叶片氮素浓度分别高于中间层（34.6%、46.4%）和下层（52.8%、66.2%）,且陕单609冠层中层和下层叶片氮素浓度较陕单8806高16.0%和40.5%。与陕单609相比,密植下陕单8806冠层上层的叶片氮素浓度高,且中下层的叶片氮素浓度较低。

图4

新窗口打开|下载原图ZIP|生成PPT
图4种植密度对不同株型玉米冠层叶片氮素浓度的影响（灌浆期）

Fig. 4Effects of planting density on canopy nitrogen concentration of different layer for different plant types of maize(grain filling stage)

2.4 增密对不同株型玉米冠层叶片衰老特性的影响

2个品种冠层不同层次叶片衰老启动的时间顺序为下部>上部>中部（图5）。冠层不同层次叶片衰老启动和衰老速率随着密度的增加而加剧。当密度超过60 000株/hm²时,陕单8806冠层上部、中部和下部叶片衰老启动的时间明显早于陕单609,且降幅更大,当密度达到90 000株/hm²时,加剧了陕单8806冠层叶片的衰老,而陕单609则表现为衰老启动慢,且生育后期维持相对较高的绿叶面积,冠层中下部更明显。在品种间,陕单609冠层上部、中部和下部绿叶面积分别在积温为744.1、760和372.7℃·d开始下降,陕单8806冠层上部、中部和下部绿叶面积分别在积温为694.6、714.1和320℃·d发生衰老,表明陕单609冠层不同层次叶片衰老的启动均晚于陕单8806,尤其是冠层中下部。

图5

新窗口打开|下载原图ZIP|生成PPT
图5密度对不同株型玉米冠层叶片衰老的影响

Fig. 5Effects of planting density on leaf senescence of different plant-type maize canopy



由表1可知,当种植密度从45 000株/hm²增加至90 000株/hm²,陕单609和陕单8806的成熟期相对绿叶面积（RGLA_m）分别降低36.4%和63.3%。随着密度的增大,2个品种叶片衰老启动时间（T_s）和相对绿叶面积最大衰减速率出现的时间（T_max）越早,相对绿叶面积的平均衰老速率（V_m）和最大衰减速率（V_max）不断增加。品种间,陕单609的RGLA_m较陕单8806高30%,T_s和T_max分别较陕单8806晚18.0 d和20.1 d,V_m和V_max分别较陕单8806低20%和10%。与陕单8806相比,陕单609在90 000株/hm²下叶片衰老的启动的时间晚,且衰老速率较低,成熟期相对绿叶面积高,说明紧凑型的陕单609密植下可延长生育后期绿叶面积的光合持续期。

Table1
表1
表1密度对不同株型玉米衰老特征的影响
Table1Effects of planting density on senescence characteristics of maize with different plant types

年份 Year	品种 Hybrid	密度 Density (plants/hm2)	方程参数		相关系数 R2	衰老性状参数
			b	c		RGLAm	Vm	Ts	Vmax	Tmax
2017	陕单609 Shaandan609	45000	6.654	0.092	0.9852	57.3	0.76	38.3	2.30	72.3
		60000	5.884	0.092	0.9912	54.2	0.82	31.8	2.31	63.7
		75000	5.344	0.097	0.9952	52.6	0.86	24.7	2.43	54.9
		90000	5.123	0.113	0.9758	40.8	1.06	19.3	2.83	45.3
	陕单8806 Shaandan8806	45000	4.525	0.084	0.9689	43.0	1.05	18.8	2.10	53.9
		60000	4.156	0.093	0.9856	33.4	1.22	13.0	2.33	44.7
		75000	3.926	0.114	0.9954	30.4	1.30	8.6	2.85	34.4
		90000	3.756	0.125	0.9921	16.7	1.50	6.5	3.13	30.0
2018	陕单609 Shaandan609	45000	6.150	0.088	0.9832	48.1	0.93	36.4	2.20	69.9
		60000	5.741	0.092	0.9856	34.9	1.02	30.4	2.30	62.4
		75000	5.543	0.098	0.9769	34.8	1.16	26.5	2.45	56.6
		90000	5.322	0.110	0.9961	26.9	1.30	21.6	2.75	48.4
	陕单8806 Shaandan8806	45000	4.368	0.091	0.9795	43.5	1.26	15.6	2.28	48.0
		60000	3.925	0.099	0.9899	35.4	1.15	9.9	2.48	39.6
		75000	3.812	0.118	0.9916	21.8	1.40	7.4	2.95	32.3
		90000	3.856	0.131	0.9857	15.1	1.59	7.0	3.28	29.4

RGLAm：成熟期相对绿叶面积;Vm：相对绿叶面积平均衰减速率;Ts：叶片衰老启动时间;Vmax：相对绿叶面积最大衰减速率;Tmax：最大绿叶衰减速率出现的时间
RGLAm: Relative green leaf area at maturity; Vm: Mean rate of decrease in RGLA; Ts: Date of onset of leaf senesence; Vmax: Maximum rate of decrease RGLA; Tmax: Date of Vmax

新窗口打开|下载CSV

2.5 增密对不同株型玉米群体氮素积累和氮收获指数的影响

如图6所示,提高种植密度增加了2个品种吐丝前后的氮素吸收量和氮收获指数,而密度超过60 000株/hm²时,陕单8806吐丝前后的氮吸收量和氮收获指数不同程度的下降。同一密度下,陕单609吐丝前后的氮素吸收量高于陕单8806,但 60 000株/hm²下,2个品种吐丝前后氮素吸收量和氮收获指数的差异不显著。当密度增至90 000株/hm²,陕单609吐丝前和吐丝后的氮素吸收量以及氮收获指数分别较陕单8806高23.5%、43.9%、12.7%。说明密度超过60 000株/hm²可能阻碍陕单8806吐丝后氮素的吸收,当密度达到90 000株/hm²时,陕单609吐丝后较高的氮素吸收量、氮收获指数的匹配保证了氮素向籽粒的迁移。

图6

新窗口打开|下载原图ZIP|生成PPT
图6种植密度对不同株型玉米吐丝前后氮素吸收和氮收获指数的影响

NHI、N_pre和N_post代表氮收获指数、吐丝前和吐丝后的植株氮素吸收量
Fig. 6Effects of planting density on nitrogen uptake (pre-silking and post silking) and nitrogen harvest index in different plant types of maize

NHI, N_pre and N_post denote the nitrogen uptake during the pre-silking and post-silking period and nitrogen harvest index

2.6 增密对不同株型玉米冠层光截获量、干物质积累和光能利用的影响

随着种植密度的增加,不同株型玉米吐丝前后的生物产量、冠层截获光合有效辐射量和光能利用率显著增加,而陕单609的收获指数先升高后降低,陕单8806则持续降低（图7）。在品种间,陕单609吐丝前的生物产量、冠层截获光合有效辐射量和光能利用效率分别较陕单8806高10.2%、低15.3%和高16.4%;陕单609吐丝后的生物产量、冠层截获光合有效辐射量和光能利用率分别较陕单8806高25.3%、高5.3%和高10.6%。陕单609和陕单8806吐丝前后的光能利用率分别在90 000株/hm²（1.359 g·MJ^-1）和60 000株/hm²（1.175 g·MJ^-1）时达到峰值。由表2可知,当密度增至90 000株/hm²时,陕单609吐丝前的生物产量、冠层截获光合有效辐射量和光能利用率分别较陕单8806高14.9%、低12.1%和高29.4%,其吐丝后的生物产量、收获指数、冠层光能截获和光能利用率均高于陕单8806（26.1%、9.1%、10.2%和14.8%）。说明密植下陕单609吐丝后具有较强的光能捕获、转化和物质生产潜力,而较高的收获指数促进了干物质向籽粒的分配,从而提高了产量。

图7

新窗口打开|下载原图ZIP|生成PPT
图7种植密度对不同株型玉米生物产量和收获指数的影响

HI、BM_pre和BM_post代表收获指数、吐丝前和吐丝后地上部干物质积累量
Fig. 7Effects of planting density on the plant biomass and harvest index of different plant-type maize

HI, BM_pre and BM_post denote the harvest index, the above-ground biomass accumulation during the pre-silking and post-silking period


Table 2
表2
表2密度对不同株型玉米吐丝前后光能截获和光能利用率的影响
Table 2Effect of planting density on intercepted photosynthetically active radiation and radiation use efficiency of different plant- type maize

年份 Year	品种 Cultivar	密度 Density (plants/hm2)	吐丝前Pre-silking		吐丝后Post-silking
			IPAR (MJ·m-2)	RUE (g·MJ-1)	IPAR (MJ·m-2)	RUE (g·MJ-1)
2017	陕单609 Shaandan609	45000	807.7d	1.046d	1033.5c	1.331d
		60000	933.4c	1.083c	1075.8b	1.482c
		75000	1021.5b	1.112b	1084.2a	1.526b
		90000	1091.7a	1.203a	1086.6a	1.539a
	陕单8806 Shaandan8806	45000	1007.2d	0.894b	997.0b	1.169c
		60000	1108.1c	0.902a	1035.1a	1.392a
		75000	1159.1b	0.886b	1020.2a	1.348b
		90000	1214.7a	0.851c	995.7b	1.345b
2018	陕单609 Shaandan609	45000	837.2c	0.824d	1004.1d	1.449c
		60000	931.2c	0.969c	1061.2c	1.497b
		75000	1028.9b	1.022b	1077.2b	1.648a
		90000	1094.3a	1.083a	1088.9a	1.611a
	陕单8806 Shaandan8806	45000	1063.4d	0.887b	991.8c	1.376b
		60000	1129.1c	0.931a	1038.8a	1.475a
		75000	1188.1b	0.862b	1026.6b	1.366b
		90000	1274.6a	0.763c	958.0d	1.337c

IPAR：截获光合有效辐射;RUE：光能利用效率
IPAR: Intercepted photosynthetically active radiation; RUE: Radiation use efficiency

新窗口打开|下载CSV

3 讨论

适宜增密是玉米生产中重要的栽培措施,而紧凑耐密品种能使个体和群体发挥最大效能,提高单位面积产量^{[2, 5]}。本试验结果显示,陕单609的平均产量较陕单8806高出3 643 kg·hm^-2,其高产对应的种植密度分别为90 000株/hm²和60 000株/hm²,表明紧凑型玉米陕单609获得高产及高产对应的种植密度均高于陕单8806,实现了密植增产,这与前人研究结果相一致^{[6, 9]}。同时陕单609的穗粒数和百粒重分别较陕单8806高23.4%和19.5%,说明密植下增加株数的同时,维持较高的粒数和粒重获得高产的重要因素。玉米产量主要由总干物质生产及其分配至籽粒的部分,即收获指数所决定^{[3, 29]},同时,籽粒产量也取决于作物在生育期内冠层光截获量和截获光能转化为生物量的效率^{[23, 30]}。本研究中,增密提高了冠层截获有效辐射、生物产量和光能利用率,且密度增至90 000株/hm²时,陕单609的生物产量、收获指数、冠层截获光合有效辐射和光能利用率均高于陕单8806。说明密植下紧凑玉米群体更高效利用太阳辐射与有效分配光合产物,导致更高的籽粒产量。

玉米籽粒产量的形成主要来源于花后干物质生产,玉米延缓花后叶片衰老是维持玉米冠层功能的重要因素,有助于获得更高的吐丝后干物质积累量和花后氮素吸收量^[1,24,28]。本研究发现,与陕单8806相比,陕单609密植下叶片衰老启动较晚,衰老速率缓慢,成熟期绿叶面积高,提高吐丝后氮素吸收与物质生产性能。另外,增密后陕单609吐丝后氮素高效吸收可维持灌浆期较高的冠层叶片氮浓度,有助于优化冠层中上部光氮分布,维持冠层中上部绿叶面积,从而延长密植群体碳获取的时间,且较高的氮收获指数和收获指数促进氮素和光合产物向籽粒的转运,使更多的光合产物形成籽粒产量。

冠层辐射截获决定了作物干物质积累和作物产量的高低,冠层光合效率主要受叶片光合能力和冠层光氮匹配程度的影响^[15,21,30]。本研究中,光能截获率和叶片氮素浓度自冠层上层至下层降低,与陕单8806相比,陕单609密植下冠层上层光能截获率低,但中间层光能截获率高,并且具有较高的叶片氮素浓度,为冠层中部叶片进行光合作用并积累能量提供重要保障,提高了生物产量和光能利用率。表明高密度下陕单609的冠层光氮分布特性可提高冠层光合效率和物质生产潜力。另外,作物光截获能力对冠层光合效率造成的差异远大于其他因素^[31,32,33]。本研究发现,当密度超过60 000株/hm²,陕单8806的辐射截获量和光能利用率明显低于陕单609,可能是生育后期陕单8806中下层叶片较早的启动衰老,而衰老叶片丧失了光合能力,因而对冠层光能截获和光合性能造成负面影响,导致群体光能利用率并不高。植株在密植环境中可通过调节叶片氮素含量来适应胁迫环境,叶片含氮量与冠层光合能力有密切的关系,且吐丝后氮素高效吸收的玉米品种能维持叶片功能^{[15, 34-36]}。本研究中,密度提高了吐丝后叶片中层和上层氮素吸收量,但当密度超过60 000株/hm²时,陕单8806吐丝后冠层叶片氮素吸收量显著降低,且明显低于陕单609。这说明陕单609密植下氮素高效吸收的特性可维持生育后期的冠层功能,以提高密植群体的冠层生产力,实现密植高产高效协同。

4 结论

陕单609和陕单8806分别在90 000株/hm²（13 824.0 kg·hm^-2）和60 000株/hm²（9 566 kg·hm^-2）达到了最高产量。紧凑型玉米陕单609密植下协同优化冠层光氮空间分布,增加了群体花后中下部光能截获量,延缓群体冠层花后中下层叶片衰老,促进群体花后干物质和氮素积累,获得更高的籽粒产量和光能利用率。因此,适当增加密度结合紧凑耐密品种是陕西灌区春玉米高产高效栽培的重要途径。

参考文献 View Option 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子

[1] 张仁和, 王博新, 杨永红, 杨晓军, 马向峰, 张兴华, 郝引川, 薛吉全. 陕西灌区高产春玉米物质生产与氮素积累特性
中国农业科学, 2017,50(12):2238-2246.
DOI:10.3864/j.issn.0578-1752.2017.12.005URL [本文引用: 2]
【Objective】The objective of this paper is to study the dry matter and nitrogen accumulation in high-yielding spring maize under irrigated conditions of Shaanxi in order to realize high and stable yield in this area. 【Method】A field experiment was conducted by different agronomic managements with the high-yielding variety shandan609 as materials from 2013 to 2015. High yielding cultivations were practiced, and then the yield and yield component, LAI, SPAD, characteristics of dry matter and nitrogen accumulation were analyzed based on the maize high-yielding cultivation. 【Result】The average yields under farmers’ practice, higher yielding cultivation, super high yielding cultivation were 11.1, 13.1 and 16.1 t·hm^-2, respectively, and 18.0% and 45.1% higher than those of control. Compared with the control, the higher yielding and super high-yielding cultivation had lower kernels per ear and thousand-kernel weights, but produced more ear number per hectare. More ears were the key to achieve maize high yield potential. The harvest indexes of higher yielding and super high-yielding cultivation were higher than that of farmers’ practice. Similarly, compared with the control, the higher yielding and super high-yielding cultivation showed more dry matter and nitrogen accumulation from silking to maturity and at maturity. In the super high-yielding cultivation, 41.8% greater dry matter production and 24.5% more nitrogen uptake after silking contributed 20.1% more to grain yield and 61.6% to grain nitrogen. Compared with the control, the higher yielding and super high-yielding cultivation also significantly increased LAI and SPAD values after silking. Grain yield was highly correlated with post-silking dry matter accumulation (r=0.988), and post-silking nitrogen accumulation (r=0.927). 【Conclusion】The results indicate that higher grain yield can be achieved by using integrated and optimized cultivation techniques under irrigated conditions of Shaanxi. The super high-yielding cultivation of spring maize has stronger photosynthetic potential, more dry matter and nitrogen accumulation (especially post-silking) and post-silking dry matter and nitrogen accumulation contributing to grain yield, thus providing a basis for production of super high-yield maize. The present study highlighted the benefits of integrating nutrient and agronomic management with matching the supply and demand of nitrogen to achieve maize high yield under irrigated conditions of Shaanxi.
ZHANG R H, WANG B X, YANG Y H, YANG X J, MA X F, ZHANG X H, HAO Y C, XUE J Q. Characteristics of dry matter and nitrogen accumulation for high-yielding maize production under irrigated conditions of Shaanxi
Scientia Agricultura Sinica, 2017,50(12):2238-2246. (in Chinese)
DOI:10.3864/j.issn.0578-1752.2017.12.005URL [本文引用: 2]
【Objective】The objective of this paper is to study the dry matter and nitrogen accumulation in high-yielding spring maize under irrigated conditions of Shaanxi in order to realize high and stable yield in this area. 【Method】A field experiment was conducted by different agronomic managements with the high-yielding variety shandan609 as materials from 2013 to 2015. High yielding cultivations were practiced, and then the yield and yield component, LAI, SPAD, characteristics of dry matter and nitrogen accumulation were analyzed based on the maize high-yielding cultivation. 【Result】The average yields under farmers’ practice, higher yielding cultivation, super high yielding cultivation were 11.1, 13.1 and 16.1 t·hm^-2, respectively, and 18.0% and 45.1% higher than those of control. Compared with the control, the higher yielding and super high-yielding cultivation had lower kernels per ear and thousand-kernel weights, but produced more ear number per hectare. More ears were the key to achieve maize high yield potential. The harvest indexes of higher yielding and super high-yielding cultivation were higher than that of farmers’ practice. Similarly, compared with the control, the higher yielding and super high-yielding cultivation showed more dry matter and nitrogen accumulation from silking to maturity and at maturity. In the super high-yielding cultivation, 41.8% greater dry matter production and 24.5% more nitrogen uptake after silking contributed 20.1% more to grain yield and 61.6% to grain nitrogen. Compared with the control, the higher yielding and super high-yielding cultivation also significantly increased LAI and SPAD values after silking. Grain yield was highly correlated with post-silking dry matter accumulation (r=0.988), and post-silking nitrogen accumulation (r=0.927). 【Conclusion】The results indicate that higher grain yield can be achieved by using integrated and optimized cultivation techniques under irrigated conditions of Shaanxi. The super high-yielding cultivation of spring maize has stronger photosynthetic potential, more dry matter and nitrogen accumulation (especially post-silking) and post-silking dry matter and nitrogen accumulation contributing to grain yield, thus providing a basis for production of super high-yield maize. The present study highlighted the benefits of integrating nutrient and agronomic management with matching the supply and demand of nitrogen to achieve maize high yield under irrigated conditions of Shaanxi.

[2] 柏延文, 杨永红, 朱亚利, 李红杰, 薛吉全, 张仁和. 种植密度对不同株型玉米冠层光能截获和产量的影响
作物学报, 2019,45(12):1868-1879.
[本文引用: 2]

BAI Y W, YANG Y H, ZHU Y L, LI H J, XUE J Q, ZHANG R H. Effect of planting density on light interception within canopy and grain yield of different plant types of maize
Acta Agronomica Sinica, 2019,45(12):1868-1879. (in Chinese)
[本文引用: 2]

[3] XU W J, LIU C W, WANG K R, XIE R Z, MING B, WANG Y H, ZHANG G Q, LIU G Z, ZHAO R L, FAN P P, LI S K, HOU P. Adjusting maize plant density to different climatic conditions across a large longitudinal distance in China
Field Crops Research, 2017,212:126-134.
[本文引用: 2]

[4] 明博, 谢瑞芝, 侯鹏, 李璐璐, 王克如, 李少昆. 2005—2016年中国玉米种植密度变化分析
中国农业科学, 2017,50(11):1960-1972.
[本文引用: 1]

MING B, XIE R Z, HOU P, LI L L, WANG K R, LI S K. Changes of maize planting density in China
Scientia Agricultura Sinica, 2017,50(11):1960-1972. (in Chinese)
[本文引用: 1]

[5] YAN P, CHEN Y Q, SUI P, VOGEL A, ZHANG X P. Effects of maize plant morphology on the formation of apical kernels at different sowing dates under different plant densities
Field Crops Research, 2018,223:83-92.
[本文引用: 2]

[6] 肖万欣, 刘晶, 史磊, 赵海岩, 王延波. 氮密互作对不同株型玉米形态、光合性能及产量的影响
中国农业科学, 2017,50(19):3690-3701.
[本文引用: 2]

XIAO W X, LIU J, SHI L, ZHAO H Y, WANG Y B. Effect of nitrogen and density interaction on morphological traits, photosynthetic property and yield of maize hybrid of different plant types
Scientia Agricultura Sinica, 2017,50(19):3690-3701. (in Chinese)
[本文引用: 2]

[7] HAKE S, RICHARDSON A. Using wild relatives to improve maize
Science, 2019,365(6454):640-641.
DOI:10.1126/science.aay5299URLPMID:31416949 [本文引用: 1]

[8] MA D L, XIE R Z, NIU X K, LI S K, LONG H L, LIU Y E. Changes in the morphological traits of maize genotypes in China between the 1950s and 2000s
European Journal of Agronomy, 2014,58:1-10.
[本文引用: 1]

[9] 徐宗贵, 孙磊, 王浩, 王淑兰, 王小利, 李军. 种植密度对旱地不同株型春玉米品种光合特性与产量的影响
中国农业科学, 2017,50(13):2463-2475.
[本文引用: 2]

XU Z G, SUN L, WANG H, WANG S L, WANG X L, LI J. Effects of different planting densities on photosynthetic characteristics and yield of different variety types of spring maize on dryland
Scientia Agricultura Sinica, 2017,50(13):2463-2475. (in Chinese)
[本文引用: 2]

[10] 李从锋, 赵明, 刘鹏, 张吉旺, 杨今胜, 柳京国, 王空军, 董树亭. 中国不同年代玉米单交种及其亲本主要性状演变对密度的响应
中国农业科学, 2013,46(12):2421-2429.
[本文引用: 1]

LI C F, ZHAO M, LIU P, ZHANG J W, YANG J S, LIU J G, WANG K J, DONG S T. Responses of main traits of maize hybrids and their parents to density in different eras of China
Scientia Agricultura Sinica, 2013,46(12):2421-2429. (in Chinese)
[本文引用: 1]

[11] LIU G Z, HOU P, XIE R Z, MING B, WANG K R, YANG Y S, XU W J, CHENG J L, LI S K. Nitrogen uptake and response to radiation distribution in the canopy of high-yield maize
Crop Science, 2019,59(3):1236-1247.
[本文引用: 1]

[12] XUE J, GOU L, ZHAO Y S, YAO H S, TIAN J S, ZHANG W F. Effects of light intensity within the canopy on maize lodging
Field Crops Research, 2016,188:133-141.
[本文引用: 1]

[13] TIAN J G, WANG C L, XIA J L, WU L S, XU G H, WU W H, LI D, QIN W C, XU H, CHEN Q Y, JIN W W, TIAN F. Teosinte ligule allele narrows plant architecture and enhances high-density maize yields
Science, 2019,365(6454):658-664.
URLPMID:31416957 [本文引用: 1]

[14] HUANG S B, GAO Y B, LI Y B, XU L C, TAO H B, WANG P. Influence of plant architecture on maize physiology and yield in Heilongjiang Rive valley
The Crop Journal, 2017, 5(1):52-62.
[本文引用: 1]

[15] MU X H, CHEN Q W, CHEN F J, YUAN L X, MI G H. Dynamic remobilization of leaf nitrogen components in relation to photosynthetic rate during grain filling in maize
Plant Physiology and Biochemistry, 2018,129:27-34.
DOI:10.1016/j.plaphy.2018.05.020URL [本文引用: 3]

[16] BERTHELOOT J, MARTRE P, ANDRIEU B. Dynamics of light and nitrogen distribution during grain filling within wheat canopy
Plant Physiology, 2008,148:1707-1720.
URLPMID:18799664 [本文引用: 1]

[17] YANG L, GUO S, CHEN F J, YUAN L X, MI G H. Effects of pollination-prevention on leaf senescence and post-silking nitrogen accumulation and remobilization in maize hybrids released in the past four decades in China
Field Crops Research, 2017,203:106-113.
DOI:10.1016/j.fcr.2016.12.022URL [本文引用: 1]

[18] ACCIARESI H A, TAMBUSSI E A, ANTONIETTA M, ZULUAGA M S, ANDRADE F H, GUIAMET J J. Carbon assimilation, leaf area dynamics, and grain yield in contemporary earlier- and later-senescing maize hybrids
European Journal of Agronomy, 2014,59:29-38.
DOI:10.1016/j.eja.2014.05.007URL [本文引用: 1]
Maize breeding during the past 50 years has been associated with a delay of leaf senescence, but it is not clear whether this trait is likewise associated with higher grain yield in modern hybrids. Post-silking growth, leaf area dynamics, photosynthetic parameters and yield were compared in modern maize hybrids differing in canopy senescence rate. In the first two experiments, four hybrids were grown in the field at Balcarce, Argentina (37 degrees 45' S, 58 degrees 18 W). In spite of differences in chlorophyll retention and photosynthesis of the ear leaf, post-silking growth and grain yield were very similar in all four hybrids while kernel N concentration was lower in the later-senescing hybrids. In a third experiment, a later-senescing (NK870) and an earlier-senescing (DK682) hybrid were grown to analyze the potential photosynthetic contribution of delayed leaf senescence. Leaf area and chlorophyll content were larger in NK870, especially at the lower canopy level (0.75 m above the ground). However, hybrids did not differ for canopy light interception. Because photosynthetic photon flux density below 1 m above the ground was less than 10% of incident radiation and photosynthesis quantum yield did not change during senescence, the potential photosynthetic output of lower leaves below 1 m was very low. Lower leaves of NK870 had N concentrations higher than those needed to sustain photosynthesis at the light conditions below 1 m. Therefore, we show that delayed senescence does not necessarily improve post-silking C accumulation because; (i) canopy light interception is not reduced by senescence except at very late stages of grain filling; (ii) contrasting hybrids show more pronounced senescence differences at canopy levels receiving less than 10% of incident radiation; (iii) delayed senescing hybrids present lower kernel N concentrations while extra N is retained in leaves exposed to a light limiting micro-environment. Delayed senescence at lower canopy levels may be unproductive, at least under non-stressing conditions. (C) 2014 Elsevier B.V.

[19] ANTONIETTAM D, FANELLO D. D, ACCIARESI H A, GUIAMET J J. Senescence and yield responses to plant density in stay green and earlier-senescing maize hybrids from Argentina
Field Crops Research, 2014,155:111-119.
DOI:10.1016/j.fcr.2013.09.016URL [本文引用: 1]
Increases in maize (Zea mays L) yield over the past few decades have been associated with breeding for tolerance to progressively higher plant densities. Since high plant density exacerbates interplant competition, it has been suggested that improved resource capture through delayed senescence might be advantageous in such situations. The main objectives of this work were to determine (1) the time-course of canopy senescence, (2) post-silking C and N accumulation and (3) yield responses of contemporary maize hybrids with different expression of the stay green (SG) character grown in a range of plant densities from moderate to intense crowding stress. Three experiments consisting of a combination of different plant densities (from 6 to 10 pl m(-2)) and commercial hybrids with different timing of senescence were carried out. High density accelerated leaf senescence at the lower canopy layer. The SG hybrids delayed senescence and retained green leaves at physiological maturity at all tested densities. One of these hybrids (NK880), with a strong SG character, retained green leaves at all canopy layers, even at the lower layer exposed to limiting irradiance. Lower canopy leaves maintained high respiratory rates in NK880, while leaves of the NSG hybrid (DK682) senesced and their respiration became not detectable. At the highest tested density, the NSG DK682 achieved greater grain yields than the SG NK880.1ncreased density reduced kernel weight (MW), and this decrease was more pronounced for the SG NK880 (6-18% comparing 10 vs. 8 pl m-2). In spite of delayed senescence in NK880, no hybrid differences were found for post-silking dry matter accumulation and plant dry matter at physiological maturity. Unexpectedly, plant nitrogen content (Nc) at harvest was similar (Exp. I) or even lower (P< 0.05, Exp. II) in the SG NK880. This was the result of lower net N accumulation during the post-silking period (Exp. I) or lower Nc achieved at silking (Exp. II) in the SG NK880. A strong positive relation was found between KW and N concentration in kernels, with %N in kernels being below the critical N concentration to achieve potential KW (around 1.4%) in the SG hybrid. This suggests that yield in NK880 was limited by N. In the SG genotype, N remobilization from vegetative organs did not seem to compensate for the N deficit for optimum grain growth. In summary, at high densities the NK880 hybrid displayed a strong, constitutive SG character, even if it accumulated less N, and senescence delay was not reflected in higher grain yield. (C) 2013 Elsevier B.V.

[20] BONELLIL E, ANDRADE F H. Maize radiation use-efficiency response to optimally distributed foliar-nitrogen-content depends on canopy leaf-area index
Field Crops Research, 2020,247:1-8.
[本文引用: 1]

[21] ZHAO J, YANG X G, LIN X M, SASSENNRATH G F, DAI S W, LV S, CHEN X C, CHEN F J, MI G H. Radiation interception and use efficiency contributes to higher yields of newer maize hybrids in Northeast China
Agronomy Journal, 2015,107(4):1473-1480.
DOI:10.2134/agronj14.0510URL [本文引用: 3]

[22] SHAO L P, LI G, ZHAO Q N, LI Y B, SUN Y T, WANG W N, CAI C, CHEN W P, LIU R H, LUO W H, YIN X Y, LEE X H. The fertilization effect of global dimming on crop yields is not attributed to an improved light interception
Global Change Biology, 2020,26(3):1697-1713.
DOI:10.1111/gcb.14822URLPMID:31479179 [本文引用: 1]
Global dimming, a decadal decrease in incident global radiation, is often accompanied with an increase in the diffuse radiation fraction, and, therefore, the impact of global dimming on crop production is hard to predict. A popular approach to quantify this impact is the statistical analysis of historical climate and crop data, or use of dynamic crop simulation modelling approach. Here, we show that statistical analysis of historical data did not provide plausible values for the effect of diffuse radiation versus direct radiation on rice or wheat yield. In contrast, our field experimental study of 3 years demonstrated a fertilization effect of increased diffuse radiation fraction, which partly offset yield losses caused by decreased global radiation, in both crops. The fertilization effect was not attributed to any improved canopy light interception but mainly to the increased radiation use efficiency (RUE). The increased RUE was explained not only by the saturating shape of photosynthetic light response curves but also by plant acclimation to dimming that gradually increased leaf nitrogen concentration. Crop harvest index slightly decreased under dimming, thereby discounting the fertilization effect on crop yields. These results challenge existing modelling paradigms, which assume that the fertilization effect on crop yields is mainly attributed to an improved light interception. Further studies on the physiological mechanism of plant acclimation are required to better quantify the global dimming impact on agroecosystem productivity under future climate change.

[23] HAO B Z, XUE Q, MAREK T H, JESSUP K E, HOU X, XU W, BYNUM E D M, BEAN B W. Radiation-use efficiency, biomass production, and grain yield in two maize hybrids differing in drought tolerance
Journal of Agronomy and Crop Science, 2016,202(4):269-280.
DOI:10.1111/jac.2016.202.issue-4URL [本文引用: 2]

[24] ZHANG L L, ZHOU X L, FAN Y, FU J, HOU P, YANG H L, QI H. Post-silking nitrogen accumulation and remobilization are associated with green leaf persistence and plant density in maize
Journal of Integrative Agriculture, 2019,18(8):1882-1892.
DOI:10.1016/S2095-3119(18)62087-8URL [本文引用: 2]

[25] HUANG S B, LV L H, ZHU J C, LI Y B, TAO H B, WANG P. Extending growing period is limited to offsetting negative effects of climate changes on maize yield in the North China Plain
Field Crops Research, 2018,215:66-73.
DOI:10.1016/j.fcr.2017.09.015URL [本文引用: 1]

[26] CHEN X C, CHEN F J, CHEN Y L, CAO Q, YANG X L, YUAN L X, ZHANG F S, MI G H. Modern maize hybrids in Northeast China exhibit increased yield potential and resource use efficiency despite adverse climate change
Global Change Biology, 2013,19(3):923-936.
URLPMID:23504848 [本文引用: 1]

[27] RICHIE J T, NESMITH D S. Temperature and crop development
Modeling Plant and Soil System, 1991,31:5-29.
[本文引用: 1]

[28] CIAMPITTI I A, VYN T J. Grain nitrogen source changes over time in maize: A review
Crop Science, 2013,53(2):366-377.
DOI:10.2135/cropsci2012.07.0439URL [本文引用: 2]
Understanding the sources of grain N uptake (Grain N) in maize (Zea mays L.) and especially the trade-off between reproductive-stage shoot N remobilization (Remobilized N) and reproductive-stage whole-plant N uptake (Reproductive N) is needed to help guide future improvements in yield and N use efficiency (NUE). Therefore, a literature review was performed to investigate the knowledge gap concerning changes over time in Grain N sources and on N partitioning to the grain and stover plant fractions at maturity. The synthesis-analysis was based on 100 reports, which were divided into two time intervals: (i) research conducted from 1940 to 1990-"Old Era"-and (ii) research conducted from 1991 to 2011-"New Era." The most remarkable results were (i) Grain N concentration was the main parameter that has changed over time, (ii) Reproductive N contributed proportionally more to Grain N for the New Era while Reproductive N and Remobilized N contributed equally to Grain N for the Old Era, (iii) Remobilized N was primarily associated with vegetative-stage whole-plant N uptake (Vegetative N), which was constant across eras, although the proportion of the Remobilized N itself seems to be driven by the ear demand, (iv) complex plant regulation processes (source: sink) appeared to influence Reproductive N, and (v) stover N concentration gains mirrored the grain N concentration as the plant N uptake increased at maturity in both eras. This new appreciation for the changes over time may assist directed selection for yield and NUE improvements.

[29] GONZALEZ V H, TOLLENAAR M, BOWMAN A. Maize yield potential and density tolerance
Crop Science, 2018,58(2):472-485.
DOI:10.2135/cropsci2016.06.0547URL [本文引用: 2]

[30] WU A, HAMMER G L, DOHERTY A, CAEMMERER S V, FARQUHAR G D. Quantifying impacts of enhancing photosynthesis on crop yield
Nature Plants, 2019,5(4):380-388.
URLPMID:30962528 [本文引用: 2]

[31] SHI D Y, LI Y H, ZHANG J W, LIU P, ZHAO B, DONG S T. Increased plant density and reduced N rate lead to more grain yield and higher resource utilization in summer maize
Journal of Integrative Agriculture, 2016,15(11):2515-2528.
DOI:10.1016/S2095-3119(16)61355-2URL [本文引用: 1]

[32] HOU W F, KHAN M R, ZHANG J L, LU J W, REN T, RUAN C L, LI X K. Nitrogen rate and plant density interaction enhances radiation interception, yield and nitrogen use efficiency of mechanically transplanted rice
Agriculture, Ecosystems & Environment, 2019,269:183-192.
[本文引用: 1]

[33] LINDQUIST J L, ARKEBAUER T J, WALTERS D T, CASSMAN K G, DOBERMANN A. Maize radiation use efficiency under optimal growth conditions
Agronomy Journal, 2005,97(1):7-78.
[本文引用: 1]

[34] CHEN W, WANG L L, SIDDIQUE K H M, DENG X P, CHEN Y L. Nitrogen vertical distribution differed in foliar and nonfoliar organs of dryland wheat during grain filling
Agronomy Journal, 2019,111(3):1218-1228.
DOI:10.2134/agronj2018.04.0243URL [本文引用: 1]

[35] MU X H, CHEN Q W, CHEN F J, YUAN L X, MI G H. Within-leaf nitrogen allocation in adaptation to low nitrogen supply in maize during grain-filling stage
Frontiers in Plant Science, 2016,7:699.
DOI:10.3389/fpls.2016.00699URLPMID:27252716
Nitrogen (N) plays a vital role in photosynthesis and crop productivity. Maize plants may be able to increase physiological N utilization efficiency (NUtE) under low-N stress by increasing photosynthetic rate (P n) per unit leaf N, that is, photosynthetic N-use efficiency (PNUE). In this study, we analyzed the relationship between PNUE and N allocation in maize ear-leaves during the grain-filling stage under low N (no N application) and high N (180 kg N ha(-1)) in a 2-year field experiment. Under low N, grain yield decreased while NUtE increased. Low-N treatment reduced the specific N content of ear leaves by 38% without significant influencing P n, thereby increasing PNUE by 54%. Under low-N stress, maize plants tended to invest relatively more N into bioenergetics to sustain electron transport. In contrast, N allocated to chlorophyll and light-harvesting proteins was reduced to control excess electron production. Soluble proteins were reduced to shrink the N storage reservoir. We conclude that optimization of N allocation within leaves is a key adaptive mechanism to maximize P n and crop productivity when N is limited during the grain-filling stage in maize under low-N conditions.

[36] ZHANG L, LIANG Z Y, HE X M, MENG Q F, HU Y C, SCHMIDHALTER U, ZHANG W, ZOU C Q, CHEN X P. Improving grain yield and protein concentration of maize (Zea mays L.) simultaneously by appropriate hybrid selection and nitrogen management
Field Crops Research, 2020,249:1-11.
[本文引用: 1]