水分和氮素对玉米苗期生长、根系形态及分布的影响

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张馨月^,, 王寅^,, 陈健, 陈安吉, 王莉颖, 郭晓颖, 牛雅郦, 张星宇, 陈利东, 高强吉林农业大学资源与环境学院/吉林省商品粮基地土壤资源可持续利用重点实验室,长春 130118

Effects of Soil Water and Nitrogen on Plant Growth, Root Morphology and Spatial Distribution of Maize at the Seedling Stage

ZHANG XinYue^,, WANG Yin^,, CHEN Jian, CHEN AnJi, WANG LiYing, GUO XiaoYing, NIU YaLi, ZHANG XingYu, CHEN LiDong, GAO QiangCollege of Resources and Environment, Jilin Agricultural University/Key Laboratory of Sustainable Utilization of Soil Resources of Jilin Commodity Grain Base, Changchun 130118

通讯作者: 王寅，E-mail：wy1986410@163.com

第一联系人: 张馨月,E-mail： zhangxy1022@163.com。
收稿日期:2018-08-20接受日期:2018-11-28网络出版日期:2019-01-01

基金资助:

国家自然科学基金青年项目.31501829
吉林省优秀青年人才基金项目.20180520036JH
国家重点研发计划.2016YFD0200101

Received:2018-08-20Accepted:2018-11-28Online:2019-01-01

摘要
【目的】东北地区春旱频发严重影响玉米出苗与苗期生长,明确水分、氮素对玉米苗期生长和根系发育的影响及其耦合效应,可为东北春玉米水、氮调控措施的优化提供依据。【方法】 2016—2017连续2年设置水分、氮素两因素盆栽试验,土壤相对含水量设4个水平,分别为重度干旱（W0,30%）、适度干旱（W1,50%）、水分适宜（W2,70%）和水分过量（W3,90%）;施氮量设3个水平,分别为不施氮（N0,0）、低氮（N1,0.12 g N·kg ^-1土）和高氮（N2,0.24 g N·kg ^-1土）。【结果】水分、氮素均显著影响玉米苗期的植株生长、根系发育、氮素吸收与利用,且两因素对植株干重、根系形态、吸氮量和氮肥利用率交互作用显著。土壤水分亏缺或过量均抑制了植株生长、干物质累积、根系发育和氮素吸收。W0处理的负面影响最为严重,其地上部干重、根系干重和植株吸氮量与W2处理相比分别降低55.5%、60.1%和47.4%,氮肥利用率下降6.4个百分点,根长和根表面积分别减少58.2%和59.5%。施氮显著促进玉米苗期植株生长与氮素吸收,降低根冠比,且不同水分条件下氮肥效应及对根系发育的影响存在明显差异。水分适宜条件下施氮促进根系生长,显著增加根长、根表面积和根体积,植株干重和吸氮量增幅最高。干旱胁迫条件下施氮抑制了根系发育,显著降低根长和根表面积,氮肥效应偏低。水分过量条件下施氮改善根系生长,但施氮效应仍低于W2处理。各水分条件下,N1处理的根长和根表面积均高于N2处理,而体积接近或更小,说明低氮增加了细根的比例。水分、氮素不仅显著影响根系形态,也导致根系空间分布出现明显差异。干旱胁迫促进根系下扎,增加深层土壤的根长分布,W0和W1处理0—12 cm土层根长比例相比W2处理分别下降11.0和8.3个百分点,而24—36 cm土层分别提高9.5和6.9个百分点。与干旱胁迫相反,水分过量趋向于增加根系在表层土壤的聚集。施氮显著促进表层土壤的根系分布,N1和N2处理0—12 cm土层根长比例相比N0处理分别增加16.3和13.7个百分点,而24—36 cm土层分别下降11.5和12.5个百分点。所有水-氮处理中,W1N1处理根系的空间分布最为均衡。【结论】水分、氮素对玉米苗期生长和根系发育有显著的耦合效应,适宜的水、氮措施可优化根系形态与空间分布,增加植株干重和氮素吸收利用。春玉米生产中建议降低氮肥基施用量以发挥水氮耦合效应,促进根系下扎和细根增殖,提高植株耐旱性和氮肥利用率。
关键词： 玉米;水分;氮素;根冠比;根系形态;根系分布

Abstract

【Objective】 The frequent spring drought has severely negative impacts on seed emergence and seedling growth in the maize production of Northeast China. It is necessary to understand the coupling effects of soil water condition and nitrogen (N) rate on maize plant and root growth at the seedling stage, and further to provide reference for optimizing water and N management in maize production of Northeast China. 【Method】In this study, two pot experiments were conducted in 2016 and 2017, with a two factor factorial design of soil water and N rates. The soil water condition included 30%, 50%, 70% and 90% of field capacity, respectively, representing severe water-stress (W0), moderate water-stress (W1), well-watered (W2) and over-watered (W3), respectively. The N rates included 0, 0.12 and 0.24 g·kg ^-1 soil, representing N-omission (N0), low N (N1) and high N (N2), respectively. 【Result】 Soil water and N rate had significant individual effects on maize plant and root growth at the seedling stage, and showed interactive effects on dry matter (DM), root morphology, N uptake, and N fertilizer use efficiency (NUE). Both soil water deficit and excess had negative impacts on maize plant growth, DM accumulation, root development, and N uptake at the seedling stage, and was especially serious under W0 treatment. Compared with W2 treatment, on average in two years, shoot and root DM and plant N uptake under W0 treatment decreased by 55.5%, 60.1% and 45.8%, respectively, NUE decreased by 7.8 percentage points. And root length (RL) and root surface area (RSA) decreased by 58.2% and 59.5%, respectively. The N fertilization improved significantly maize plant growth and N uptake but reduced root/shoot ratio at the seedling stage. Moreover, the plant and root growth responses of N fertilizer differed obviously with the different soil water conditions. The N fertilization improved root growth in terms of higher RL, RSA and root volume (RV) under W2 treatment, and therefore showed the highest plant DM and N uptake. However, N fertilization limited root growth and decreased significantly RL and RSA under W0 and W1 treatments. The N fertilization also improved root growth under W3 treatment, but the N fertilizer response was still lower than that under W2 treatment. Across all the soil water conditions, maize plants showed higher RL and RSA under N1 treatments than that under N2 treatments, but the RV was equal or smaller, indicating that low N supply induced fine root development at the seedling stage. Soil water and N rate not only affected significantly maize root morphology, but also had great effects on root system spatial distribution. The water-stress induced deeper root growth and RL distribution in subsoil. Compared with W2 treatment, on average, the distribution ratio of RL in 0-12 cm soil layer decreased by 11.0 percentage points under W0 treatment and 8.3 percentage points under W1 treatment, but their distribution ratio in 24-36 cm soil layer increased by 9.5 and 6.9 percentage points, respectively. In contrast to soil water-stress condition, maize root system showed a concentrated trend in topsoil under over-watered condition. The N fertilization improved significantly root distribution in topsoil. Compared with N0 treatment, the RL distribution ratio increased by 16.3 and 13.7 percentage points higher in 0-12 cm soil layer under N1 and N2 treatments, respectively, and the distribution ratio decreased by 11.5 and 12.5 percentage points lower in 24-36 cm soil layer, respectively. Across all the soil water-N treatments, maize root system showed the more balanced spatial distribution under the W1N1 treatment.【Conclusion】Soil water condition and N rate had significant coupling effects on maize seedling growth and root development. The appropriate soil water and N management could optimize root morphology and spatial distribution, and improve plant DM accumulation and N uptake. Therefore, we suggested reducing basal N rate to stimulate deeper root growth with more fine root by inducing the water-N coupling effect, and further to enhance plant resistance to drought stress and to improve NUE in spring maize production of Northeast China.

Keywords：maize;water;nitrogen;root/shoot ratio;root morphology;root spatial distribution

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本文引用格式
张馨月, 王寅, 陈健, 陈安吉, 王莉颖, 郭晓颖, 牛雅郦, 张星宇, 陈利东, 高强. 水分和氮素对玉米苗期生长、根系形态及分布的影响[J]. 中国农业科学, 2019, 52(1): 34-44 doi:10.3864/j.issn.0578-1752.2019.01.004
ZHANG XinYue, WANG Yin, CHEN Jian, CHEN AnJi, WANG LiYing, GUO XiaoYing, NIU YaLi, ZHANG XingYu, CHEN LiDong, GAO Qiang. Effects of Soil Water and Nitrogen on Plant Growth, Root Morphology and Spatial Distribution of Maize at the Seedling Stage[J]. Scientia Acricultura Sinica, 2019, 52(1): 34-44 doi:10.3864/j.issn.0578-1752.2019.01.004

0 引言

【研究意义】东北地区是我国玉米主产区和重要的商品粮基地,2016年黑龙江、吉林和辽宁三省玉米种植面积和总产量分别占全国的30.3%和33.8%,在全国玉米生产和粮食供应中占有重要地位^[1]。该地区春玉米种植属典型的雨养农业系统,降水不足导致的干旱胁迫是限制玉米生产的主要环境因素,常常导致玉米受灾减产^[2,3,4]。近五年除2016年降雨较多外,其余年份东北地区均遭遇大面积干旱。其中,2014年8月严重的夏伏旱导致辽宁、吉林近3.33×10⁶ hm²农田受旱,玉米总产量较2013年减产超过4×10⁶ t。本年度（2018年）4月中旬至5月下旬,吉林中西部、辽宁大部地区降水普遍减少一半以上,部分严重地区甚至不足往年同期的20%,导致玉米播种和出苗受到极大影响,全面减产几成定局。研究显示,东北地区未来增温趋势明显,干旱发生频率将大幅增加^{[3, 5]}。因此,急需加强春玉米抗旱减灾的栽培与施肥技术研究以应对日益严重的干旱胁迫,保障高产稳产。【前人研究进展】东北地区春玉米不同生长阶段,吐丝期干旱对产量造成的影响最为严重,而苗期干旱发生的频率最高,“十年九春旱”极大影响了玉米出苗和苗期生长^{[4, 6]}。研究表明,苗期干旱胁迫显著降低玉米叶片的光合能力和电子传递速率,抑制幼苗营养生长,严重时甚至对后期生殖生长造成不利影响^[7,8,9]。但是,适度的苗期干旱可改变根系形态,并提高植株渗透调节、碳氮代谢和酶促防御等方面能力,对后期生长具有补偿和激发作用^[10,11,12]。由此,一些****提出了调亏灌溉、交替灌溉、根区灌溉等节水灌溉技术,通过不同灌溉措施人为创造适度的土壤干旱条件以发挥“炼苗”作用,提高植株耐旱性以促进后期生长,从而提高水分利用效率^{[13,14,15,16,17]}。施用氮肥是促进玉米生长和获得高产的重要措施,但东北玉米生产中农户普遍过量施氮且大多为一次性基施,极易造成苗期旺长、氮素损失及环境污染^{[18,19,20,21]}。已有研究显示,合理施氮可以促进干旱条件下作物根系生长,提高根系活力和水肥吸收能力,增强植株抗性,从而减轻或恢复由于干旱胁迫而造成的不利影响^[22,23,24]。但是,不同土壤水分条件下氮素可能发挥不同的作用。CLAY等^[25]研究发现,水分充足、重度干旱条件下施氮对小麦生长分别表现出正向和负向的调节作用,而轻度干旱条件下无明显影响。夏玉米上的研究显示,氮肥作用受控于土壤水分状况,干旱限制了氮肥的施用效果,导致根系生物量和生理特性下降,而适度补充灌水则增强了氮肥作用,促进根系生长并改善了生理特性^[26]。可见,水分和氮素对作物的生长发育具有复杂的交互作用,通过合理的水、氮调控发挥其耦合效应是促进作物生长、提高耐旱性的重要技术途径。【本研究切入点】水分和氮素对玉米植株生长、生理特性和产量形成等方面已有较多研究,但针对苗期阶段的研究还相对较少,尤其是对根系生长、形态和空间分布的影响还不清楚。【拟解决的关键问题】本研究通过设置盆栽试验,研究不同水、氮组合条件下玉米苗期植株的生长发育、根系形态与空间分布、氮素吸收与利用状况,以期为春玉米抗旱减灾的水肥管理措施提供依据。

1 材料与方法

1.1 试验材料

2016—2017年在吉林农业大学资源与环境学院科研基地温室内开展盆栽试验,选用玉米品种为良玉99。供试土壤均为吉林农业大学科研基地试验大田的黑土,pH 6.58,有机质含量为2.57 g·kg^-1,碱解氮含量为93 mg·kg^-1,有效磷含量为13.8 mg·kg^-1,速效钾含量为130.9 mg·kg^-1,风干过5 mm筛。盆栽试验采用高45 cm、口径42 cm的塑料桶,桶内可装55 kg干土,桶底部铺一层鹅卵石和纱布作为过滤层,防止盆底滞水,塑料桶内部沿桶边缘等距离插入三根口径3 cm的PVC管用于灌水。

1.2 试验设计

盆栽试验设置土壤水分、施氮量两个因素,土壤相对含水量设置4个水平：30%、50%、70%和90%,分别为重度干旱（W0）、适度干旱（W1）、水分适宜（W2）和水分过量（W3）,施氮量设置3个水平：0、0.12和0.24 g N·kg^-1土,分别为不施氮（N0）、低氮（N1）和高氮（N2）。除氮肥外,每盆施入等量的磷、钾和锌肥,每千克干土用量分别为0.15 g P₂O₅、0.15 g K₂O和0.02 g ZnSO₄。氮、磷、钾肥分别采用尿素（N 46%）,重钙（P₂O₅ 46%）和氯化钾（K₂O 60%）。所有肥料称好后与过筛干土搅拌均匀装入桶中,而后灌水使土壤相对含水量保持在70%并静置3 d使土壤自然沉降。每个处理设4次重复,完全随机排列,定期进行倒盆调整。2年盆栽试验均于6月上旬播种,每盆播种3株,二叶期间苗定植1株。控水前,所有处理的土壤相对含水量统一维持在70%,于4叶期开始按照设计的水分梯度进行控水。W2区组维持70%土壤相对含水量,W0和W1区组通过自然落干分别达到50%和30%的土壤相对含水量,W3增加灌水达到90%土壤相对含水量。控水时间维持2周,每天通过称重法维持设计的土壤水分含量。盆栽控水期内,玉米植株总干重的变化量占总灌水量的比例低于0.25%,因此植株自身干重的变化对于补充灌水量来讲可忽略不计。

1.3 项目测定与方法

控水结束当天,割去整个地上部植株装入网袋中带回实验室,105℃杀青30 min,75℃烘干至恒重获得地上部干重。2016年采用分层法挖取根系,以6 cm一层共分6层进行取样。每层土块取出后装入网眼直径1 mm的尼龙网袋,采用低压流水冲洗,冲洗干净后采用EPSON V800高分辨率扫描仪进行图像扫描,而后使用WinRHIZO根系分析系统分析根系长度、表面积、体积等参数。完成形态扫描后,收集所有根系样品75℃烘干至恒重获得根系干重。2017年对根系进行整体挖掘,清洗后直接烘干获取干重数据,未进行形态扫描。

1.4 数据处理

试验数据采用Excel 2013软件进行计算处理,采用SPSS 17.0软件进行双因素方差分析,用LSD法比较处理间在P=0.05水平上的差异显著性。

2 结果

2.1 水分、氮素对玉米苗期植株生长的影响

表1显示,氮素显著影响2年试验中玉米苗期的株高、茎粗和SPAD值,而水分显著影响了除2016年SPAD值外的所有指标,两因素对苗期植株生长指标均未表现出显著的交互作用。干旱胁迫抑制了玉米苗期植株生长,2年试验中W0和W1处理的株高、茎粗及2017年SPAD值均显著低于W2处理。水分过量对植株苗期生长的影响较小,除2017年SPAD值外,W3处理与W2处理的各项指标均无显著差异。施氮显著提高了各水分条件下玉米苗期的株高、茎粗和叶片SPAD值,但N1和N2处理间并无显著差异。茎粗作为反映植株生长健壮的重要指标,2年试验W2条件下N1和N2处理的植株茎粗相比N0处理分别增加22.2%和25.4%,而W0、W1和W3条件下N1处理的平均增幅分别为15.9%、18.7%和20.6%,N2处理平均增幅分别为21.4%、23.1%和21.2%。可见,氮素对玉米茎粗的增幅在不同水分条件下存在明显差异,干旱胁迫和水分过量均降低了氮肥的施用效果,尤其以严重干旱胁迫的负面影响最大。

Table 1
表1
表1水分、氮素对春玉米苗期植株生长的影响
Table 1Effects of soil water and N rate on maize plant growth at seedling stage

土壤水分 Soil water condition	施氮量 N rate	2016年			2017年
土壤水分 Soil water condition	施氮量 N rate	株高 Plant height (cm)	茎粗 Stem diameter (cm)	SPAD	株高 Plant height (cm)	茎粗 Stem diameter (cm)	SPAD
W0	N0	60.4bB	19.7bB	28.8bA	73.4bC	25.3bB	32.0bC
	N1	79.7aB	23.7aB	44.3aA	80.5aC	28.6aC	42.9aB
	N2	82.5aB	23.9aB	45.7aA	83.1aC	30.9aC	44.9aB
W1	N0	71.7bA	31.8bA	32.9bA	82.5bBC	32.6bA	35.2bB
	N1	88.7aB	39.2aA	43.0aA	96.4aB	37.2aB	44.1aB
	N2	91.3aB	40.4aA	45.4aA	101.5aB	38.9aB	47.0aB
W2	N0	79.8bA	32.9bA	29.9bA	93.0bAB	34.4bA	36.7bAB
	N1	117.4aA	42.0aA	45.7aA	124.6aA	40.2aA	45.0aB
	N2	112.3aA	41.8aA	44.5aA	130.3aA	42.6aA	47.2aB
W3	N0	80.3bA	32.1bA	30.1bA	96.7bA	33.8bA	38.7bA
	N1	111.2aA	40.4aA	46.6aA	120.8aA	39.1aAB	48.0aA
	N2	115.3aA	41.8aA	45.5aA	125.1aA	38.0aB	50.1aA
方差分析 ANOVA
水分 W		<0.001 ***	<0.001 ***	0.893 ^ns	<0.001 ***	<0.001 ***	<0.001 ***
氮素 N		0.0016 **	<0.001 ***	<0.001 ***	<0.001 ***	0.032 *	<0.001 ***
水分×氮素 W×N		0.126 ^ns	0.551^ns	0.694 ^ns	0.083 ^ns	0.332 ^ns	0.879 ^ns

In the ANOVA results, *, ** and *** indicate significant differences between treatments at P=0.05, P=0.01 and P=0.001 levels, respectively. The different lowercase letters followed means indicate significant differences between N rates under the same soil water condition, and the different capital letters followed means indicate significant differences between soil water conditions under the same N rate. The same as below
方差分析结果中*, **和***分别表示处理间在P=0.05、P=0.01和P=0.001水平上存在显著差异,ns表示差异不显著（P>0.05）。同一水分条件下,不同小写字母表示施氮量间差异显著;同一施氮量下,不同大写字母表示水分处理间差异显著。下同

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2.2 水分、氮素对玉米苗期地上部和根系干重的影响

水分、氮素对玉米苗期植株的地上部和根系干重及根冠比均有显著影响,且两因素对地上部和根系干重表现出显著交互作用（表2）。干旱胁迫和水分过量均降低了苗期植株的地上部和根系干重。与W2处理相比,2年试验中W0处理地上部和根系干重平均下降55.5%和60.1%,W1处理平均下降27.4%和23.1%,W3处理则平均下降7.6%和9.1%。W1处理提高了根冠比,W0和W3处理则表现为下降趋势,尤其是W0处理的根冠比下降了10.6%。施氮显著提高了所有水分条件下植株的地上部干重,2年试验W2条件下N1和N2处理相比N0处理平均增加1.01和0.90倍,而W0、W1和W3条件下N1处理的平均增幅分别为32.2%、48.4%和79.9%,N2处理平均增幅分别为34.8%、58.7%和91.3%。施氮对W0条件下植株的根系干重无显著促进作用,但显著提高了W1、W2和W3条件的根系干重,2年试验中,N1处理相比N0处理分别增加35.8%、68.8%和57.3%,N2处理分别增加27.6%、53.6%和61.3%。可见,施氮条件下根系干重的增幅低于地上部干重,因此根冠比明显下降。干旱胁迫条件下施氮导致根冠比的下降更为明显,W0条件下N1和N2处理较N0处理平均下降19.6%和26.8%,W1条件下则分别为7.4%和18.8%。结果表明,玉米苗期植株干物质累积和分配对氮素的响应受水分条件的显著影响,干旱胁迫和水分过量条件下低量施氮可在兼顾较高植株干重的情况下减少根冠比降幅。

Table 2
表2
表2水分、氮素对玉米苗期地上部干物质量、根系干重和根冠比的影响
Table 2Effects of soil water and N rate on shoot and root dry matter and their ratio of maize plant at seedling stage

土壤水分 Soil water condition	施氮量 N rate	2016			2017
土壤水分 Soil water condition	施氮量 N rate	地上部干重 Shoot dry matter (g)	根系干重 Root dry matter (g)	根冠比 R/S ratio	地上部干重 Shoot dry matter (g)	根系干重 Root dry matter (g)	根冠比 R/S ratio
W0	N0	26.0bB	4.8aB	0.19aA	22.9bC	5.8aC	0.25aAB
	N1	34.9aD	5.3aD	0.15bB	29.7aC	6.0aD	0.20bB
	N2	36.5aD	4.9aD	0.13bB	29.4aC	5.5aC	0.19bA
W1	N0	39.6bA	8.3bA	0.21aA	32.3bB	8.8bB	0.27aA
	N1	63.3aC	12.4aC	0.20aA	43.4aB	10.9aC	0.25abA
	N2	65.7aC	11.2aC	0.17bA	48.4aB	10.7aB	0.22bA
W2	N0	40.5bA	8.4cA	0.21aA	41.7bA	10.8bA	0.26aAB
	N1	92.8aA	16.6aA	0.18bA	72.1aA	15.8aA	0.22bAB
	N2	87.3aA	14.8bA	0.17bA	68.9aA	14.7aA	0.21bA
W3	N0	37.2bA	7.5bA	0.20aA	41.8bA	10.1bAB	0.24aB
	N1	76.1aB	14.1aB	0.19abA	66.1aA	13.6aB	0.21bB
	N2	78.6aB	13.2aB	0.17bA	72.6aA	15.2aA	0.21bA
方差分析 ANOVA
水分 W		<0.001 ***	<0.001 ***	0.003 **	<0.001 ***	<0.001 ***	0.031 *
氮素 N		<0.001 ***	<0.001 ***	0.022 *	<0.001 ***	<0.001 ***	0.001 **
水分×氮素 W×N		<0.001 ***	<0.001 ***	0.846 ^ns	<0.001 ***	0.002 **	0.749 ^ns

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2.3 水分、氮素对玉米苗期根系形态的影响

水分、氮素均显著影响玉米苗期的根系形态,且两因素显示出显著交互作用（表3）。所有处理中,根长和根表面积均以W2N1处理最高而W0N2处理最低,根体积则以W2N2处理最高而W0N0处理最低。总体上,干旱胁迫和水分过量均抑制了苗期的根系生长,显著降低根长、根表面积和根体积。与W2处理相比,W0处理的根长、根表面积和根体积平均下降58.2%、59.5%和65.1%,W1处理分别下降35.8%、32.9%和24.2%,而W3处理分别下降10.2%、13.5%和24.1%。不同水分条件下根系生长对氮素的响应存在显著差异,干旱胁迫条件下施氮对根长和根表面积显示出负向抑制作用,而水分适宜与过量条件下则表现出正向促进作用。以根长为例,W2条件下N1和N2处理相比N0处理分别增加35.0%和14.9%,而W0条件下分别下降31.3%和38.3%,W1条件下降幅相对较小,分别为9.9%和27.6%。施氮增加了所有水分条件下根系的体积,W2处理增幅最高,其次为W3和W2处理,W1处理最低。与N2处理相比,N1处理的根系体积接近或较低,根长和根表面积则相对较高,说明低氮条件下根系的平均直径较小,细根比例较高。

Table 3
表3
表3水分、氮素对玉米苗期根系形态的影响
Table 3Effects of soil water and N rate on maize root morphology at seedling stage

土壤水分 Soil water condition	施氮量 N rate	根长 Root length (m)	根表面积 Root surface area (m²)	根体积 Root volume (cm³)
W0	N0	122.1aB	0.75aB	38.5aC
	N1	83.8bD	0.60bD	42.4aD
	N2	75.3bC	0.57bD	39.1aD
W1	N0	164.8aA	1.08aA	66.4cA
	N1	148.5aC	1.12aC	105.5aB
	N2	119.2bB	0.99aC	89.2bC
W2	N0	192.4cA	1.21bA	62.9cAB
	N1	259.7aA	1.81aA	116.8bA
	N2	221.0bA	1.73aA	164.6aA
W3	N0	174.3bA	1.09cA	57.5cB
	N1	221.4aB	1.59aB	93.5bC
	N2	208.9aA	1.43bB	110.3aB
方差分析 ANOVA
水分 W		< 0.001 ***	< 0.001 ***	< 0.001 ***
氮素 N		< 0.001 ***	0.002 **	< 0.001 ***
水分×氮素 W×N		< 0.001 ***	< 0.001 ***	< 0.001 ***

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2.4 水分、氮素对玉米苗期根长空间分布的影响

春玉米苗期根长在土壤剖面不同土层中整体上呈“纺锤状”分布,中层土壤中的比例较高,而表层和深层土壤的比例相对较低（图1—2）。W2处理表层土壤（0—12 cm）、中层土壤（12—24 cm）和深层土壤（24—36 cm）的玉米平均根长分别为83.6、97.8和42.8 m,分布比例平均为37.2%、43.7%和19.1%。干旱胁迫条件下表层土壤的玉米根长明显下降,而深层土壤的分布比例明显提高。与W2处理相比,W0和W1处理0—12 cm土层根长比例平均下降11.0和8.3个百分点,而24—36 cm土层根长比例平均提高9.5和6.9个百分点。与干旱胁迫相反,水分过量条件下根系呈现在表层土壤聚集的趋势,W3处理0—12 cm土层根长比例相比W2处理平均提高4.2个百分点,而24—36 cm土层根长比例平均下降了3.4个百分点。氮素对玉米苗期根长的空间分布也显示出巨大影响,施氮促进根系在表层土壤的增殖,分布比例明显提高。相比N0处理,N1和N2处理0—12 cm土层根长比例平均增加16.3和13.7个百分点,12—24 cm土层变化较小,平均下降4.8和1.1个百分点,而24—36 cm土层平均下降11.5和12.5个百分点。不同水分条件下,施氮后根长分布的变化也存在差异,W0处理根长比例的变幅明显较小,而W2处理的变幅则相对较大。结果表明,干旱胁迫促进了春玉米根系下扎,而充足或过量的水分及氮肥施用增加了根系表聚,综合来看适量干旱结合减量施氮（W1N1处理）有助于玉米苗期形成较均衡的根系分布。

图1

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图1水分、氮素对玉米苗期不同土层根长的影响

Fig. 1Effects of soil water and N rate on maize root length across different soil layers at seedlings stage

图2

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图2水分、氮素对玉米苗期不同土层根长分布比例的影响

Fig. 2Effects of soil water and N rate on distribution ratio of maize root length across different soil layers at seedlings stage

2.5 水分、氮素对玉米苗期植株氮素吸收与利用的影响

2年试验中,水分、氮素均显著影响玉米苗期植株的氮素吸收量和氮肥利用率,且两因素对吸氮量表现出显著的交互作用（图3）。干旱胁迫降低了植株吸氮量,2016年W0和W1处理与W2处理相比平均下降了47.1%和13.4%,而2017年则下降了47.7%和28.9%。水分过量条件下植株吸氮量略有下降,但与W2处理差异并不显著。各水分条件下植株吸氮量均随施氮量的增加而持续提高。相比N0处理,N1处理吸氮量平均提高了2.2倍,而N2处理提高了2.9倍。所有水氮组合处理中,以W2N2处理的植株吸氮量最高,2016和2017年分别为2.08和1.84 g N/株。水分适宜条件下玉米植株的氮肥利用率最高,2016年N1和N2处理分别为23.4%和13.1%,2017年则分别为12.0%和8.8%。干旱胁迫和水分过量均降低了氮肥利用率,两年结果平均来看,W0、W1和W3处理的氮肥利用率相比W2处理分别下降了6.4、3.7和2.25个百分点,其中2016年降幅较2017年更高。所有水分条件下,N2处理的氮肥利用率均显著低于N1处理,两年中W0、W1、W2和W3条件下分别降低2.9、4.1、6.7和6.0个百分点。结果表明,充足的水分条件和适量的氮素供应有利于提高植株的氮素吸收与利用。

图3

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图3水分、氮素对玉米苗期植株吸氮量和氮肥利用率的影响

柱子内不同大写字母表示同一施氮量条件下水分处理间存在显著差异,柱子上方的*表示同一水分条件下施氮量间存在显著差异
Fig. 3Effects of soil water and N rate on N uptake and N fertilizer use efficiency of maize plant at seedlings stage

The different capital letters in the bars indicate significant differences between soil water conditions under the same N rate, and the * above the bars indicate significant difference between N rates under the same soil water condition

3 讨论

水分和氮素是保障作物良好生长的重要物质基础,两者相互制约、相互作用,适宜的水-氮措施可有效发挥耦合效应,实现高产稳产与水肥高效^{[15, 21-22, 27]}。已有研究表明,水分、氮素对植株不同生育阶段的干物质积累与分配均有显著影响。一般来说,土壤干旱或氮素胁迫条件下,作物为增强对水分、养分的吸收会增加同化物在根系中的分配以促进根系生长,从而提高根系的相对干重与根冠比;相反地,水分、氮素充足条件则导致根冠比下降^[28,29,30]。本研究表明,水分、氮素均显著影响了玉米苗期的植株生长、地上部干重、根系干重及根冠比,并对干物质累积与分配表现出显著的交互作用。与已有研究类似,本研究中不施氮处理的根冠比显著高于施氮处理,轻度干旱胁迫处理的根冠比与水分适宜处理相比也明显较高。因此,所有水-氮处理中以W1N0处理的根冠比最高。但是,本研究中重度干旱胁迫处理的根冠比与水分适宜处理相比有所下降,原因可能是严重且持续的水分缺乏阻碍了干物质从地上向根系的转移,导致根冠比反而下降,这可能造成根系伤害难以恢复并影响后期生长。

一方面,作物根系的形态与空间分布决定了根系构型,并进一步影响根系从土壤获取水分、养分资源的能力^[31,32,33]。另一方面,作物根系构型具有很强的可塑性,土壤环境、水肥资源的变化均会对其产生显著影响^[31,34]。SHARP等^[35]发现,干旱条件下作物根系变细,横向生长减弱而增加向土壤深层的扩展以寻找、利用深层土壤中的水分。与水分胁迫类似,氮素缺乏也会诱导根系变细并增加纵向扩展,促进根系在下层土壤的增殖,而高氮则抑制根系纵向扩展、促进根系横向生长^[36,37]。与以上研究一致,本研究结果也显示出水分、氮素对春玉米苗期根系形态和空间分布所具有的重要调控作用。而且,笔者发现水、氮两因素之间存在着显著的交互作用,两者供应状况的上调与下降对根系形态和空间分布具有明显的叠加效应。干旱胁迫与氮素缺乏组合条件下,玉米苗期的根长、根表面积和根体积均显著下降,但同时大幅提高了根系在土壤深层的分布比例,极大地促进了根系下扎。而水分适宜和过量条件下,施氮明显促进了根系生长,各项形态指标均显著较高,但根系在土壤深层的分布比例显著下降,导致了根系大量表聚。一般来说,较深的根系分布有利于植株增加对深层土壤水分、养分的获取,可提高植株水肥利用效率,增强耐旱性及抗倒伏能力,而较浅的根系分布在土壤肥力较低、环境胁迫较严重的条件下极易导致植株养分缺乏或加重胁迫伤害^{[32-33, 37]}。因此,通过适宜的水、氮措施发挥耦合效应而调控苗期根系构型,是促进玉米后期生长发育、提高植株抗性和水肥利用效率的重要途径。

综合本研究结果,不同水分条件下N1处理的植株干重与N2处理均无显著差异,而根冠比的下降幅度相对较小,说明苗期低氮供应更有利于干物质在根系的分配,从而促进了根系扩展,并增加了细根数量,表现出相比N2处理更大的根长与根表面积,而且适度干旱胁迫条件下N1处理的根系分布更为均衡。因此,降低氮肥基施用量有助于发挥水氮耦合效应,促进根系下扎和细根增殖,从而提高干旱抗性和氮肥利用率。

4 结论

水分和氮素对玉米苗期的植株干重、吸氮量、根系形态及分布表现出显著的交互作用。土壤水分亏缺或过量均抑制了玉米苗期生长、干物质累积和氮素吸收。施氮促进各水分条件下玉米的植株生长与氮素吸收,但降低了根冠比。干旱胁迫条件下,施氮抑制了根系发育,显著降低根长和根表面积,因此加重了植株的受旱表现。干旱胁迫促进玉米苗期根系下扎,而水分过量则导致根系在表层土壤聚集。施氮提高了表层土壤的根系分布,并在水分充足或过量条件下表现出明显的叠加效应。所有水-氮处理中,以适度干旱与低量施氮处理的根系空间分布最为均衡。相比高氮处理,各水分条件下低氮处理的根长、根表面积及细根比例更高,因此植株生长表现接近且氮肥利用率显著更高。因此,东北春玉米生产中建议减少氮肥基施用量以发挥水氮耦合效应,促进根系下扎和细根增殖,提高植株耐旱性和氮肥利用率。

参考文献原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子

[1]

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[本文引用: 1]

[2]

王崇桃, 李少昆 . 玉米生产限制因素评估与技术优先序
中国农业科学, 2010,43(6):1136-1146.

URL Magsci [本文引用: 1]

【目的】明确中国玉米生产的主要限制因素和技术发展优先领域。【方法】采用参与式方法,对中国主产省和东北春玉米、黄淮海春、夏播玉米和西南山地玉米三大主产区生产限制因素进行评估,并基于限制因素影响程度、解决的可能性评估,建立玉米生产技术优先序。【结果】当前限制中国玉米产量潜力实现的主要因素：一是以耕作栽培管理粗放、施肥方法不科学、技术到位率低等为主的栽培管理技术问题,在不同生态区玉米产量损失占28.8%—57.7%;二是以干旱为主的自然逆境因素,产量损失占9.3%—35.1%;三是玉米品种遗传基础狭窄,品种“多、乱、杂”、缺乏高产稳产的区域主导品种,良种良法配套差以及种子质量问题,产量损失占11.4%—19.8%;四是水土流失、耕层浅、土壤瘠薄等土壤障碍因素,产量损失占4.8%—20.2%;五是病、虫、草、鼠等生物逆境危害,产量损失占4.5%—11.0%。【结论】加强“轻、简、化”栽培技术研究;选育耐密、抗逆、广适高产优质品种,并筛选确立区域主导品种;推进科技入户和玉米生产机械化,提高技术到位率是近期政府制定相关玉米生产政策时应考虑的重要领域。

WANG C

, LI S

. Assessment of limiting factors and techniques prioritization for maize production in China
Scientia Agricultura Sinica, 2010,43(6):1136-1146. (in Chinese)

URL Magsci [本文引用: 1]

YIN

, OLESEN J

, WANG

, KERSEBAUM K

, CHEN

, MOHAN

, ?ZTüRK

, CHEN

. Adapting maize production to drought in the Northeast Farming Region of China
European Journal of Agronomy, 2016,77:47-58.

DOI:10.1016/j.eja.2016.03.004 URL [本文引用: 2]

Maize (Zea maysL.) is the most prominent crop in the Northeast Farming Region of China (NFR), and drought has been the largest limitation for maize production in this area during recent decades. The question of how to adapt maize production to drought has received great attention from policy makers, researchers and farmers. In order to evaluate the effects of adaptation strategies against drought and examine the influences of policy supports and farmer households’ characteristics on adopting decisions, a large scale household survey was conducted in five representative maize production counties across NFR. Our survey results indicated that using variety diversification, drought resistant varieties and dibbling irrigation are the three major adaptation strategies against drought in spring, and farmers also adopted changes in sowing time, conservation tillage and mulching to cope with drought in spring. About 20% and 18% of households enhanced irrigation against drought in summer and autumn, respectively. Deep loosening tillage and organic fertilizer are also options for farmers to resist drought in summer. Maize yield was highly dependent on soil qualities, with yields on land of high soil quality approximately 1050kg/ha and 2400kg/ha higher than for normal and poor soil conditions, respectively. Using variety diversification and drought resistant varieties can respectively increase maize yield by approximately 150 and 220kg/ha under drought. Conservation tillage increased maize yield by 438–459kg/ha in drought years. Irrigation improved maize yield by 419–435kg/ha and 444–463kg/ha against drought in summer and autumn, respectively. Offering information service, financial and technical support can greatly increase the use of adaptation strategies for farmers to cope with drought. However, only 46% of households received information service, 43% of households received financial support, and 26% of households received technical support against drought from the local government. The maize acreage and the irrigation access are the major factors that influenced farmers’ decisions to apply adaptation strategies to cope with drought in each season, but only 25% of households have access to irrigation. This indicates the need for enhanced public support for farmers to better cope with drought in maize production, particularly through improving access to irrigation.

[4]

张淑杰, 张玉书, 孙龙彧, 纪瑞鹏, 蔡福, 武晋雯, 李广霞 . 东北地区玉米生育期干旱分布特征及其成因分析
中国农业气象, 2013,34(3):350-357.

DOI:10.3969/j.issn.1000-6362.2013.03.016 URL Magsci [本文引用: 2]

利用1961-2008年东北地区124个气象站的日气象数据，定义了表征玉米不同生育时期干旱强度的水分亏缺指标，并对干旱时空分布及其年际变化特征进行分析。结果表明，东北地区玉米生长季内干旱呈明显的季节性和区域性。从发育阶段看，苗期干旱频率较高，随生育期后移干旱频率明显减少，以轻旱为主要发生类型，春秋降水量少是发生干旱的主要原因；从空间分布看，干旱呈东北向西南逐渐增加的趋势，区域性较明显，总体上为辽宁西北部、吉林西部至黑龙江西南部发生频率较高。各年代之间比较，20世纪60-80年代干旱频率呈减少趋势，90年代初期呈增加趋势，90年代中期以后增加趋势明显，特别是2000-2004年维持在一个较高水平。各年代干旱发生频率均表现为苗期＞拔节-孕穗期＞灌浆-成熟期＞抽雄-开花期。苗期和拔节-孕穗期干旱发生频率均以60年代较高，以轻度干旱为主要发生类型；抽雄-开花期干旱发生频率以90年代较高，以轻度干旱为主要发生类型；灌浆-成熟期轻、中、重度干旱发生频率均以2001-2008年为高。由此可见，研究区干旱发生频率呈增高趋势，特别是玉米产量形成关键期的干旱频率呈增加趋势，对玉米生产的不利影响增大。研究结果对了解东北地区玉米不同发育期干旱分布特征及其成因，并采取相应对策措施具有积极意义。

ZHANG S

, ZHANG Y

, SUN L

, JI R

, CAI

, WU J

, LI G

. Analysis of distributional characteristics and primary causes of maize drought in Northeast China
Chinese Journal of Agrometeorology, 2013,34(3):350-357. (in Chinese)

DOI:10.3969/j.issn.1000-6362.2013.03.016 URL Magsci [本文引用: 2]

LIU

, HUBBARD K

, LIN

, YANG

. Negative effects of climate warming on maize yield are reversed by the changing of sowing date and cultivar selection in Northeast China
Global Change Biology, 2013,19:3481-3492.

[本文引用: 1]

[6]

冯冬蕾, 程志刚, 吴琼, 朱津辉, 曲骅倩, 李吉 . 基于MCI指数的东北地区1961-2014年气象干旱特征分析
干旱区资源与环境, 2017,31(10):118-124.

DOI:10.13448/j.cnki.jalre.2017.323 URL [本文引用: 1]

文中利用东北地区208个国家气象站1961-2014年逐日气温和降水量资料,根据气象干旱综合监测指数(MCI)计算公式,并且依据当前气象干旱等级国家标准对干旱过程及干旱强度进行定义。分析东北地区近54年来发生干旱过程的时空特征。结果表明:春季是东北地区干旱发生的主要季节;东北平原地区干旱严重;而辽宁东部和吉林南部受干旱影响最小。近54年来,东北地区发生干旱过程的年际强度变化上与干旱的范围年际变化特征基本吻合。通过REOF的时空分析,将东北地区大致分成三个区域模态:辽河平原模态,大兴安岭中部模态及三江平原模态,并且各模态中干旱强度随时间变化趋势不同。

FENG D

, CHENG Z

, WU

, ZHU J

, QU H

, LI

, Meteorological drought characteristics in Northeast China from 1961 to 2014 based on the comprehensive monitoring index analysis
Journal of Arid Land Resources and Environment, 2017,31(10):118-124. (in Chinese)

DOI:10.13448/j.cnki.jalre.2017.323 URL [本文引用: 1]

张仁和, 薛吉全, 浦军, 赵兵, 张兴华, 郑友军, 卜令铎 . 干旱胁迫对玉米苗期植株生长和光合特性的影响
作物学报, 2011,37(3):521-528.

DOI:10.3724/SP.J.1006.2011.00521 URL Magsci [本文引用: 1]

以2个不同抗旱性玉米品种郑单958 (抗旱性强)和陕单902 (抗旱性弱)为材料，采用盆栽控水试验，设置轻度干旱，中度干旱，重度干旱和正常灌水处理，研究了干旱胁迫对2个玉米品种植株生长、气体交换和叶绿素荧光参数的影响。结果显示，干旱胁迫抑制2个玉米品种植株生长和相对生长速率，导致整株生物量显著下降。随着干旱胁迫程度加剧，叶片最大净光合速率(Pnmax)、表观量子效率(AQY)、光饱和点(LSP)、气孔导度(Gs)、气孔限制值(Ls)、最大电子传递速率(ETRm)、光能利用效率(α)、光系统II的实际量子产量(ΦPSII)和光化学猝灭系数(qP)均下降，而胞间CO2浓度(Ci)，光补偿点(LCP)和非光化学猝灭系数(qN)均升高。可见，干旱胁迫下叶片光合能力和电子传递速率降低是2个玉米品种生物量减少的主要因素。但郑单958变化幅度小于陕单902，表明郑单958植株生长发育和光合特性比陕单902受干旱胁迫的影响小，较高的电子传递速率、较强的光能转化能力和较大的相对生长速率是郑单958适应干旱环境的重要生理特性。

ZHANG R

, XUE J

, PU

, ZHAO

, ZHANG X

, ZHENG Y

, BU L

. Influence of drought stress on plant growth and photosynthetic traits in maize seedlings
Acta Agronomica Sinica, 2011,37(3):521-528. (in Chinese)

DOI:10.3724/SP.J.1006.2011.00521 URL Magsci [本文引用: 1]

FLEXAS

, BOTA

, CIFRE, J, MARIANO ESCALONA

, GALMES

, GULIAS

, LEFI

, MARTINEZ-CANELLAS

, MORENO

, RIBAS-CARBO

, RIERA

, SAMPOL

, MEDRANO

. Understanding down-regulation of photosynthesis under water stress: Future prospects and searching for physiological tools for irrigation management
Annals of Applied Biology, 2004,144(3):273-283.

DOI:10.1111/j.1744-7348.2004.tb00343.x URL [本文引用: 1]

Abstract Photosynthetic down-regulation and/or inhibition under water stress conditions are determinants for plant growth, survival and yield in drought-prone areas. Current knowledge about the sequence of metabolic events that leads to complete inhibition of photosynthesis under severe water stress is reviewed. An analysis of published data reveals that a key regulatory role for Rubisco in photosynthesis is improbable under water stress conditions. By contrast, the little data available for other Calvin cycle enzymes suggest the possibility of a key regulatory role for some enzymes involved in the regeneration of RuBP. There are insufficient data to determine the role of photophosphorylation. Several important gaps in our knowledge of this field are highlighted. The most important is the remarkable scarcity of data about the regulation/inhibition of photosynthetic enzymes other than Rubisco under water stress. Consequently, new experiments are urgently needed to improve our current understanding of photosynthetic down-regulation under water stress. A second gap is the lack of knowledge of photosynthetic recovery after irrigation of plants which have been subjected to different stages of water stress. This knowledge is necessary in order to match physiological down-regulation by water stress with controlled irrigation programmes.

[9]

马树庆, 王琪, 张铁林, 于海, 徐丽萍, 纪玲玲 . 吉林省中部玉米出苗率和产量对播种-出苗期水分胁迫的反应及其气象评估
应用生态学报, 2014,25(2):451-457.

URL Magsci [本文引用: 1]

<div >2010—2011年春季，在吉林省中部玉米主产区开展春玉米水分胁迫和分期播种双处理试验，分析玉米出苗率和产量对土壤水分胁迫的反应，建立基于气象条件的玉米出苗率和干旱减产评估模式.结果表明：研究期间，研究区春玉米出苗率和单产与0～20 cm土壤湿度和土壤有效水含量的关系均呈显著的二次函数关系，耕层土壤水分越充足，玉米出苗率和产量越高，干旱明显降低玉米出苗率和产量.土壤湿度在22%～24%或土壤有效水量在50～65 mm，玉米出苗率和产量较高；土壤湿度<19%或土壤有效水量<35 mm，玉米出苗率和产量明显下降.土壤湿度每下降1%，出苗率下降约6%，产量降低约7%；耕层有效水量每减少10 mm，玉米出苗率降低约13%，减产约14%.本文所设指标和模式可用于玉米出苗率和干旱减产的评估与预测.</div><div > </div>

MA S

, WANG

, ZHANG T

, YU

, XU L

, JI L

. Response of maize emergence rate and yield to soil water stress in period of seeding emergence and its meteorological assessment in central area of Jilin province
Chinese Journal of Applied Ecology, 2014,25(2):451-457. (in Chinese)

URL Magsci [本文引用: 1]

SHARP R

, POROYKO

, HEJLEK L

, SPOLLEN W

, SPRINGER G

, BPHNERT H

, NGUYEN

. Root growth maintenance during water deficits: Physiology to functional genomics
Journal of Experimental Botany, 2004,55(407):2343-2351.

DOI:10.1093/jxb/erh276 URLPMID:15448181 [本文引用: 1]

Abstract Progress in understanding the network of mechanisms involved in maize primary root growth maintenance under water deficits is reviewed. These include the adjustment of growth zone dimensions, turgor maintenance by osmotic adjustment, and enhanced cell wall loosening. The role of the hormone abscisic acid (ABA) in maintaining root growth under water deficits is also addressed. The research has taken advantage of kinematic analysis, i.e. characterization of spatial and temporal patterns of cell expansion within the root growth zone. This approach revealed different growth responses to water deficits and ABA deficiency in distinct regions of the root tip. In the apical 3 mm region, elongation is maintained at well-watered rates under severe water deficit, although only in ABA-sufficient roots, whereas the region from 3-7 mm from the apex exhibits maximum elongation in well-watered roots, but progressive inhibition of elongation in roots under water deficit. This knowledge has greatly facilitated discovery of the mechanisms involved in regulating the responses. The spatial resolution with which this system has been characterized and the physiological knowledge gained to date provide a unique and powerful underpinning for functional genomics studies. Characterization of water deficit-induced changes in transcript populations and cell wall protein profiles within the growth zone of the maize primary root is in progress. Initial results from EST and unigene analyses in the tips of well-watered and water-stressed roots highlight the strength of the kinematic approach to transcript profiling.

[11]

梁爱华, 马富裕, 梁宗锁, 慕自新 . 旱后复水激发玉米根系功能补偿效应的生理学机制研究
西北农林科技大学学报(自然科学版), 2008,36(4):58-64.

DOI:10.3321/j.issn:1671-9387.2008.04.011 URL [本文引用: 1]

【目的】揭示干湿交替环境下植物或栽培作物发生补偿效应的生理学机制,为现代生物学节水的实践研究以及植物抗旱机制的理论研究提供理论依据。【方法】在琼脂-聚乙二醇（Agar-PEG）培养介质中,从根系结构变化、C、N代谢、渗透调节以及活性氧防御系统的优化等方面,对旱后复水诱导玉米根系功能发生补偿效应的生理学机制进行初探。【结果】干旱胁迫下玉米根系活力明显减弱,而复水后,随着复水时间的推移,诱发出大量的新侧根和根毛,代谢功能增强,补偿或部分补偿了干旱胁迫造成的危害。可溶性糖在体内进行了重新分配,运往根系的可溶性糖显著增多。除Gly和Ala含量在干湿交替处理和干旱胁迫处理中无差异外,复水处理的其他游离氨基酸及其总量均介于一直胁迫和一直湿润处理之间,而且两两间的差异达显著水平。复水处理在维持根系较低的O2^-和H2O2含量的同时,提高了SOD和CAT的活性,减小了膜脂过氧化危害和离子泄露,具有预警作用。【结论】旱后复水玉米光合产物向根系的重新分配、Pro和其他游离氨基酸含量的增加、活性氧清除和防御系统的优化、以及新生侧根和根毛的形成,可能正是干湿交替水环境下玉米根系功能产生补偿效应的生理学基础。

LIANG A

, MA F

, LIANG Z

, MU Z

. Studies on the physiological mechanism of functional compensation effect in maize root system induced by re-watering after draught stress. Journal of Northwest A&
F University (Natural Science Edition), 2008,36(4):58-64. (in Chinese)

DOI:10.3321/j.issn:1671-9387.2008.04.011 URL [本文引用: 1]

刘吉利, 赵长星, 吴娜, 王月福, 王铭伦 . 苗期干旱及复水对花生光合特性及水分利用效率的影响
中国农业科学, 2011,44(3):469-476.

DOI:10.3864/j.ssn.0578-1752.2011.03.005 URL Magsci [本文引用: 1]

【目的】揭示苗期不同程度水分胁迫后复水对花生光合特性和水分利用效率的影响,以期为花生节水高产栽培提供理论依据。【方法】采用防雨棚池栽法,对比分析花生苗期不同程度的干旱及复水处理下花生光合速率、耗水量、产量和水分利用效率等相关指标的变化。【结果】花生苗期干旱,光合速率与蒸腾速率降低,干旱持续时间越长降低越明显,复水后光合速率和蒸腾速率均能较快恢复,产生一定的补偿效应;同时苗期干旱导致花生耗水量减少,且干旱程度越重耗水量越小;但水分利用效率并不随耗水量的减少而降低,干旱5 d处理产量水平的水分利用效率最高,对照次之,干旱15 d处理的最低。【结论】苗期适度干旱可减少花生的耗水量,提高产量水平的水分利用效率。

LIU J

, ZHAO C

, WU

, WANG Y

, WANG M

. Effects of drought and rewatering at seedling stage on photosynthetic characteristics and water use efficiency of peanut
Scientia Agricultura Sinica, 2011,44(3):469-476. (in Chinese)

DOI:10.3864/j.ssn.0578-1752.2011.03.005 URL Magsci [本文引用: 1]

KANG S

, SHI W

, ZHANG J

. An improved water-use efficiency for maize grown under regulated deficit irrigation
Field Crops Research, 2000,67(3):207-214.

DOI:10.1016/S0378-4290(00)00095-2 URL [本文引用: 1]

The rapid decline of water resources on the semi-arid loess plateau in northwest China has led to the urgent need to reduce irrigation. Regulated deficit irrigation (RDI), i.e. a controlled soil water deficit applied at certain periods of a crop season, can save water and may maintain the yield. In this paper, the timing and the extent of RDI were studied in a field experiment on maize crops for 2 years (1996 1997) in this area. Controlled soil water deficit, either mild (50 60% of field capacity) or severe (40 50%), was applied at both the seedling and the stem-elongation stages. Stomatal resistance and leaf photosynthesis of water-stressed plants rapidly recovered to the control level 3 days after rewatering if such regulated water deficit was applied at the seedling stage. Controlled soil water deficit also inhibited the stem-elongation, stimulated root system development and therefore resulted in a substantially enhanced root-to-shoot ratio. Soil water deficit at the seedling stage apparently had no significant influence on the final grain yield, but the plants droughted at the seedling stage were better adapted to the later soil water deficit at the stem-elongation stage. Grain yield of plots that were well irrigated during the seedling stage was substantially reduced by the soil drying at the stem-elongation stage. However, the grain yield of those plots that were subjected to a soil drying at the seedling stage was not significantly reduced by a further mild soil drying (55% of field capacity at the minimum) at the stem-elongation stage. Grain yield of these plots was similar (no significant difference) to the always well-irrigated control. Water-use efficiency for these plots was substantially improved as a result. It is therefore recommended that a soil drying at the seedling stage plus a further mild soil drying at the stem-elongation stage is the optimum irrigation method for the maize production in this semi-arid area.

[14]

郭相平, 康绍忠, 索丽生 . 苗期调亏处理对玉米根系生长影响的试验研究
灌溉排水学报, 2001,20(1):25-27.

DOI:10.3969/j.issn.1672-3317.2001.01.006 URL [本文引用: 1]

以玉米为试验材料，利用盆栽试验研究了调亏灌溉对苗期根系形态、活力和干物质累积的影响。试验结果表明：调亏灌溉减少根系干物质累积，根冠比、平均根长和根系活力(TTC还原量)提高；单株根系条数下降：根系活力在复水后仍保持较高水平。表明调亏在量上抑制根系生长，但在形态和吸收功能上表现出一定的补偿效应。

GUO X

, KANG S

, SUO L

. Effects of regulated deficit irrigation on root growth in maize
Irrigation and Drainage, 2001,20(1):25-27. (in Chinese)

DOI:10.3969/j.issn.1672-3317.2001.01.006 URL [本文引用: 1]

以玉米为试验材料，利用盆栽试验研究了调亏灌溉对苗期根系形态、活力和干物质累积的影响。试验结果表明：调亏灌溉减少根系干物质累积，根冠比、平均根长和根系活力(TTC还原量)提高；单株根系条数下降：根系活力在复水后仍保持较高水平。表明调亏在量上抑制根系生长，但在形态和吸收功能上表现出一定的补偿效应。

[15]

HU T

, KANG S

, LI, F

, ZHANG J

. Effects of partial root-zone irrigation on the nitrogen absorption and utilization of maize
Agricultural Water Management, 2009,96(2):208-214.

DOI:10.1016/j.agwat.2008.07.011 URL [本文引用: 2]

To investigate the dynamic change of plant nitrogen (N) absorption and accumulation from different root zones under the partial root-zone irrigation (PRI), maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed partial root-zone irrigation, FPRI), or alternatively on one of two sides (alternate partial root-zone irrigation, APRI). And the isotope-labeled 15N-(NH 4) 2SO 4 was applied to one half of the container with ( 14NH 4) 2SO 4 to the other half so that N inflow rates can be tracked. Results showed that APRI treatment increased root N absorption in the irrigated zone significantly when compared to that of CI treatment. The re-irrigated half resumed high N inflow rate within 5 days after irrigation in APRI, suggesting that APRI had significant compensatory effect on N uptake. The amount of N absorption from two root zones of APRI was equal after two rounds of alternative irrigation (20 days). The recovery rate, residual and loss percentages of fertilizer-N applied to two zones were similar. As for FPRI treatment, the N accumulation in plant was mainly from the irrigated root zone. The recovery rate and loss percentage of fertilizer-N applied to the irrigated zone was higher and the residual percentage of fertilizer-N in soil was lower if compared to those of the non-irrigated zone. The recovery rate of fertilizer-N in APRI treatment was higher than that of the non-irrigated zone but lower than that of the irrigated zone in FPRI treatment. In total, both FPRI and APRI treatments increased N and water use efficiencies but only consumed about 70% of the irrigated water when compared to CI treatment.

[16]

KANG S

, HAO X

, DU T

, TONG

, SU X

, LU H

, LI X

, HUO Z

, LI S

, DING R

. Improving agricultural water productivity to ensure food security in China under changing environment: From research to practice
Agricultural Water Management, 2017,179:5-17.

DOI:10.1016/j.agwat.2016.05.007 URL [本文引用: 1]

Irrigation is an important measure for increasing grain production. Improving water use efficiency in agriculture is expected to play a very important role in ensuring food and water security in China, since there is a serious problem between food supply and limited water resources in China. The present state and future trend of water and food security in China were analyzed, while the importance of irrigation in ensuring China food security was highlighted based on the analysis of the evolution of irrigation water productivity in recent 60 years and its relationships with changes of crop yield, cropping pattern, fertilization and irrigation water use. Research progresses and practical application on high-efficient agricultural water use in China were introduced, and two successful cases of improving agricultural water productivity in China were presented, one was to improve crop water use efficiency by the novel irrigation method based on crop physiological responses, and the other was to improve the regional water productivity by the integrative methods in the Shiyang River Basin of Northwest China. The major research areas needed to focus on in the future were discussed, which include responses of crop water demand to changing environment and associated spatio-temporal optimization of water allocation, multi-processes hydrologic cycle of irrigated land under strong influences of human activities, integrated measures for improving multi-scale agricultural water use efficiency, and interactions between grain production, water resources and ecological system and its sustainability analysis in a systematic way.

[17]

ADU

, YAWSON

, ARMAH

, ASARE

, FRIMPONG

. Meta-analysis of crop yields of full, deficit, and partial root-zone drying irrigation
Agricultural Water Management, 2018,197:79-90.

DOI:10.1016/j.agwat.2017.11.019 URL [本文引用: 1]

Techniques that reduce the volume of water applied in irrigation are desirable in the face of dwindling water resources and increasing demand for food. Various water-saving irrigation strategies, involving, the application of water below full crop-water requirements, have been advanced. This study employed meta-analysis to examine the relative crop yield performance of full irrigation (FI), deficit irrigation (DI) and partial root-zone drying irrigation (PRDI). The review included 35 studies, representing 14 study countries, and reporting 43 crop yields of (i) DI against that of PRDI; (ii) FI against that of DI; and (iii) FI against that of PRDI. Overall, crops under DI produces similar yields as PRDI but yields under both are typically lower than yields of FI. There were variations in yield response of different crops to DI and PRDI, suggesting crop and/or context-specificity. The main factors contributing to the yield response were crop species and soil texture. Crop yields between FI, DI and PRDI vary significantly if crops are more frequently irrigated. It is concluded that DI and PRDI result in yields lower than those of FI but yields of DI and PRDI are comparable. Economically justifying and weighing the cost of water-saving irrigation strategies against the expected yield penalties is therefore crucial.

[18]

GAO

, LI C

, FENG G

, WANG J

, CUI Z

, CHEN X

, ZHANG F

. Understanding yield response to nitrogen to achieve high yield and high nitrogen use efficiency in rainfed corn
Agronomy Journal, 2012,104(1):165-168.

DOI:10.2134/agronj2011.0215 URL [本文引用: 1]

Abstract Chinese farmers believe that more fertilizer and higher grain yields are synonymous. A better understanding of the relationship between corn (Zea mays L.) yields and N rate could help agronomists match fertilizer rates with plant requirements. The objective of this study is to evaluate corn yield response to applied N fertilizer and to understand the factors affecting yield response to N fertilizer by 737 on-farm experiments in northeastern China. Corn grain yield without applied N fertilizer averaged 7.6 Mg ha -1. Increased yield for applied N fertilizer (IY N, the difference between maximum yield across all treatments and yield of the N0 treatment) averaged 2.5 Mg ha -1 and varied from 0 to 9.3 Mg ha -1. Farmers' practices and corn hybrids resulted in large variability in IY N, whereas no changes in IYN occurred among years or soil types. Under the current cropping system, the maximum corn yield significantly increased and IYN decreased with increasing yield of the N0 treatment, suggesting that increasing IY N with high yield of the N0 treatment using integrated hybrids along with strategic management of crops, soils, and N is crucial for achieving high yields with a high N use efficiency (NUE).

[19]

PENG

, LI

. Temporal and spatial profiling of root growth revealed novel response of maize roots under various nitrogen supplies in the field
PLoS ONE, 2012,7(5):e37726.

DOI:10.1371/journal.pone.0037726 URLPMID:3356300 [本文引用: 1]

A challenge for Chinese agriculture is to limit the overapplication of nitrogen (N) without reducing grain yield. Roots take up N and participate in N assimilation, facilitating dry matter accumulation in grains. However, little is known about how the root system in soil profile responds to various N supplies. In the present study, N uptake, temporal and spatial distributions of maize roots, and soil mineral N (Nmin) were thoroughly studied under field conditions in three consecutive years. The results showed that in spite of transient stimulation of growth of early initiated nodal roots, N deficiency completely suppressed growth of the later-initiated nodal roots and accelerated root death, causing an early decrease in the total root length at the rapid vegetative growth stage of maize plants. Early N excess, deficiency, or delayed N topdressing reduced plant N content, resulting in a significant decrease in dry matter accumulation and grain yield. Notably, N overapplication led to N leaching that stimulated root growth in the 40 50 cm soil layer. It was concluded that the temporal and spatial growth patterns of maize roots were controlled by shoot growth and local soil Nmin, respectively. Improving N management involves not only controlling the total amount of chemical N fertilizer applied, but also synchronizing crop N demand and soil N supply by split N applications.

[20]

WANG G

, CHEN X

, CUI Z

, ZHANG F

. Estimated reactive nitrogen losses for intensive maize production in China
Agriculture Ecosystems & Environment, 2014,197:293-300.

DOI:10.1016/j.agee.2014.07.014 URL [本文引用: 1]

A thorough understanding of reactive N (Nr) losses from N fertilization applications and the factors that influence it is necessary to better evaluate various Nr losses mitigation scenarios and improve N management practices. The objectives of this study were to develop empirical models to calculate Nr losses using meta-analysis and to evaluate trade-offs among grain yield, N recovery efficiency (REN), and Nr loss intensity for in-season N management for intensive summer maize (Zea mays L.) production in China. A meta-analysis with 55 studies and 170 observations suggested that both N2O emissions and N leaching increased exponentially with the N application rate or N surplus, while NH3 volatilization increased linearly with the N application rate. According to regression curves, models based on the N rate (N-R) and N surplus (N-S) were used to estimate Nr losses. Because the N-R did not account for large variations in REN or grain yield across farmers’ fields for difference competence in N management, estimated Nr losses were a little higher than those estimated by the N-S, especially for high-yield, high-REN systems. Across 162 on-farm experimental sites, an in-season root-zone N management strategy with a 39% lower N application rate and 6% higher grain yield increased the REN by 98% (from 16% to 31%) and reduced Nr loss intensity (based on the N-S) by 45% (from 13.6 to 7.5kgNMg611) compared to farmers’ typical N practices. In conclusion, the reconciliation of food security with greater environmental protection for the future can be driven by improved agronomic management to increase grain yield as well as REN, rather than by solely focusing on optimizing the N application rate.

[21]

YIN G

, GU

, ZHANG F

, LIU Z

. Maize yield response to water supply and fertilizer input in a semi-arid environment of Northeast China
PLoS ONE, 2014,9(1):e86099.

DOI:10.1371/journal.pone.0086099 URLPMID:24465896 [本文引用: 2]

Maize grain yield varies highly with water availability as well as with fertilization and relevant agricultural management practices. With a 311-A optimized saturation design, field experiments were conducted between 2006 and 2009 to examine the yield response of spring maize (Zhengdan 958, Zea mays L) to irrigation (I), nitrogen fertilization (total nitrogen, urea-46% nitrogen,) and phosphorus fertilization (P2O5, calcium superphosphate-13% P2O5) in a semi-arid area environment of Northeast China. According to our estimated yield function, the results showed that N is the dominant factor in determining maize grain yield followed by I, while P plays a relatively minor role. The strength of interaction effects among I, N and P on maize grain yield follows the sequence N+I >P+I>N+P. Individually, the interaction effects of N+I and N+P on maize grain yield are positive, whereas that of P+I is negative. To achieve maximum grain yield (10506.0 kg·ha611) for spring maize in the study area, the optimum application rates of I, N and P are 930.4 m3·ha611, 304.9 kg·ha611 and 133.2 kg·ha611 respectively that leads to a possible economic profit (EP) of 10548.4 CNY·ha611 (CNY, Chinese Yuan). Alternately, to obtain the best EP (10827.3 CNY·ha611), the optimum application rates of I, N and P are 682.4 m3·ha611, 241.0 kg·ha611 and 111.7 kg·ha611 respectively that produces a potential grain yield of 10289.5 kg·ha611.

[22]

李生秀, 李世清, 高亚军, 王喜庆, 贺海军 . 施用氮肥对提高旱地作物利用土壤水分的作用机理和效果
干旱地区农业研究, 1994,12(1):38-46.

URL [本文引用: 2]

在年降水量４５０－５１０ｍｍ的半湿润易旱地区的壤质红垆土上，以春玉米为供试作进行了大田试验。玉米生长期间，每隔１０天分别测定不同栽培和施氮量处理的的蒸腾强度，叶面积，伤流量，伤流液成分，叶水势，叶片糖分含量，并刈割玉米地上部分，测定生长量，分层采取２ｍ土层的土壤，测定含水量，以研究施用Ｎ肥对提高旱地作物利用土壤水分的作用机理和效果。试验表明，施用氮肥促进了作物根系发育，扩大了作物觅取水分和养分的土

LI S

, LI S

, GAO Y

, WANG X

, HE H

. The mechanism and effects of N fertilization in increasing water use efficiency
Agricultural Research in the Arid Areas, 1994,12(1):38-46. (in Chinese)

URL [本文引用: 2]

张艳, 张洋, 陈冲, 李东, 翟丙年 . 水分胁迫条件下施氮对不同水氮效率基因型冬小麦苗期生长发育的影响
麦类作物学报, 2009,29(5):844-848.

DOI:10.7606/j.issn.1009-1041.2009.05.019 URL Magsci [本文引用: 1]

为了明确水分胁迫条件下施氮对小麦苗期生长发育的影响，采用室内水培试验，以两个不同水氮效率基因型冬小麦品种(小偃6号和小偃22)为供试材料，在不同水分条件（5% PEG 6000胁迫和正常水分供应）下，设置三个氮水平(低氮:0.1 mmol/L；中氮1.4 mmol/L；高氮2.8 mmol/L)，研究了水分胁迫下氮肥对不同水氮效率基因型冬小麦苗期株高、叶面积、植株含水率和含氮量及地上、地下生物量的影响。结果表明，同正常供水相比，除根冠比外，水分胁迫明显抑制了冬小麦幼苗的生长发育，使地上生物量、株高、叶面积、植株含氮量和含水率显著降低；适量供氮减小了降低的程度，且小偃22的表现优于小偃6号。说明水分胁迫条件下适量供氮能够减轻干旱对冬小麦生长发育的影响，水氮高效型品种小偃22较水氮低效型品种小偃6号对水分和氮素胁迫具有更强的适应性。

ZHANG

, ZHANG

, CHEN

, LI

, ZHAI B

. Effect of water stress and nitrogen application on growth and development of winter wheat genotypes with different water and nitrogen use efficiency at seedling stage
Journal of Triticeae Crops, 2009,29(5):844-848. (in Chinese)

DOI:10.7606/j.issn.1009-1041.2009.05.019 URL Magsci [本文引用: 1]

王秀波, 上官周平 . 干旱胁迫下氮素对不同基因型小麦根系活力和生长的调控
麦类作物学报, 2017,37(6):820-827.

DOI:10.7606/j.issn.1009-1041.2017.06.014 URL [本文引用: 1]

为了探讨不同水氮耦合处理对小麦根系活力和吸收氮素能力的影响,以多穗型小麦品种西农979和大穗型小麦品系2036为材料进行营养液培养试验,设置正常水分供应、轻度和重度水分胁迫及低氮、中氮和高氮处理,研究了不同水氮耦合对小麦根系形态、根系吸收面积、根系活力、植株氮素积累量的影响。结果表明,水分与氮素存在着明显的互作效应,重度水分胁迫和低氮处理都会降低小麦的生物量、根系总吸收面积、活跃吸收面积和活力、氮含量和植株的氮素积累量,低氮处理增加了根长和根冠比。高氮处理的西农979根系总吸收面积、活跃吸收面积和活力较低,中氮处理显著提高,且分别比2036高11%、14%、27%。西农979在中氮和高氮处理之间的氮素积累量无显著性差异。中氮处理下西农979的植株氮素积累量比2036高13%~62%。相关分析表明,小麦的活跃吸收面积、根系活力与植株氮素积累量呈极显著正相关（P〈0.01）,和根冠比呈极显著负相关（P〈0.01）。在轻度水分胁迫下,增加氮素供给能有效提高西农979的根系吸收面积和根系活力;过高的氮素不利于2036根系的生长,表明不同基因型小麦的根系活力和生长对不同水氮耦合的响应不同。通过适宜的水氮耦合调控,有利于创造良好的小麦根系形态,提高根系活力及对水分和养分的吸收能力。

WANG X

, SHANGGUAN Z

. Effect of nitrogen on root vigor and growth in different genotypes of wheat under drought stress
Journal of Triticeae Crops, 2017,37(6):820-827. (in Chinese)

DOI:10.7606/j.issn.1009-1041.2017.06.014 URL [本文引用: 1]

CLAY D

, ENGEL R

, LONG

, LIU

. Nitrogen and water stress interact to influence carbon-13 discrimination in wheat
Soil Science Society of America Journal, 2001,65(6):1823-1828.

DOI:10.2136/sssaj2001.1823 URL [本文引用: 1]

[26]

宋海星, 李生秀 . 水、氮供应和土壤空间所引起的根系生理特性变化
植物营养与肥料学报, 2004,10(1):6-11.

DOI:10.3321/j.issn:1008-505X.2004.01.002 URL Magsci [本文引用: 1]

在限制根系生长的胁迫条件下.,研究了补充和不补充供应水、氮对玉米根系生理特性及养分吸收的影响。结果表明.,正常生长条件下.,水、氮供应促进了根系生长.,增加了根系吸收总面积、活跃吸收面积和TTC还原量.,促进了根系对养分的吸收.,从而提高了产量.;限制根系生长.,水分的作用与正常条件下相同.,氮素的作用则受控于土壤水分。补充灌水增强了氮肥作用.,供氮促进了根系生长.,改善了根系生理特性.,减少了限制根系生长所引起的不良影响.;不补充灌水限制了氮肥作用的发挥.,供氮导致了根系生物量和生理特性下降.,加重了限制根系生长的不良影响。

SONG H

, LI S

. Changes of root physiological characteristics resulting from supply of water, nitrogen and root-growing space in soil
Plant Nutrition and Fertilizer Science, 2004,10(1):6-11. (in Chinese)

DOI:10.3321/j.issn:1008-505X.2004.01.002 URL Magsci [本文引用: 1]

HOKAM

, EI-HENDAWY

, SCHMIDHALTER

. Drip irrigation frequency: The effects and their interaction with nitrogen fertilization on maize growth and nitrogen use efficiency under arid conditions
Journal of Agronomy and Crop Science, 2011,197(3):186-201.

DOI:10.1111/j.1439-037X.2010.00460.x URL [本文引用: 1]

Differences in soil moisture and wetting pattern under different irrigation frequencies mean that vegetative growth and nitrogen use efficiency in maize can differ even when the same total amount of irrigated water is applied under different frequency regimes. The goal of this study was to evaluate the effects of drip irrigation frequency and its interaction with nitrogen fertilization on vegetative growth and nitrogen use efficiency of a maize crop at different growth stages and on grain quality at maturity stage in a sandy soil. The experiment was conducted for 2 years (2005 and 2006) using a randomized complete block split–split plot design with four irrigation frequencies (once every 2, 3, 4 and 5 days), two nitrogen levels (190 and 380 kg N ha611) and two maize hybrids (three-way cross 310 and single cross 10) as the main-plot, split-plot and split–split plot variables, respectively. Irrigation water, totalling 524 mm ha611, applied for each irrigation frequency was divided into 28, 21, 17 and 14 doses for the F2, F3, F4 and F5 treatments, respectively. Results indicated that vegetative growth, crop growth and nitrogen efficiency parameters at the 10-leaf and tasseling growth stages increased with increasing drip irrigation frequency, whereas grain protein content decreased. Although the values of the vegetative growth and crop growth parameters increased with increasing nitrogen levels, significant decreases in nitrogen efficiency parameters were also observed indicating the need for further optimization with a reduced nitrogen application rate. Significant interaction effects between irrigation frequency and nitrogen levels were detected for all parameters measured. In most cases, the parameters were not significantly different between the two nitrogen levels at an irrigation frequency of once every 5 days, but did differ significantly at irrigation frequencies of once every 2, 3 or 4 days. The relationship between the nitrogen use efficiency parameters and retained available soil water content at the 10-leaf and tasseling growth stages was best represented by a second order polynomial equation with an R2 ranging from 0.73 to 0.98. Based on our findings, an irrigation frequency of once every 2 and 3 days is recommended to enhance growth and nitrogen use efficiency of drip-irrigated maize in sandy soil in Egypt.

[28]

ANDERSON E

. Tillage and N fertilization effects on maize root growth and root﹕shoot ratio
Plant & Soil, 1988,108(2):245-251.

DOI:10.1007/BF02375655 URL [本文引用: 1]

Two methods for estimating the size of the maize (Zea mays 1.) root system from soil cores taken in the field were compared. The spatially weighed block method of estimation accounted for variation in root density by using 18 samples per plant which varied in distance from plant and soil depth. This method was compared to an estimation which averaged all of the 18 samples together. Both methods gave surprisingly similar estimates for total root growth. Increased root growth in the surface soil layers, due to tillage and N fertilization, did not impact on the estimation of total root growth. Total root length remained unchanged or increased with N fertilization, while root weight remained the same or decreased. Root mass per length decreased with N fertilization. The estimated size of the root system was used to calculate root: shoot weight ratios. The largest root: shoot ratio was found in the vegetative stage and decreased throughout the rest of the season. In this field experiment, the estimated size of the root system at 8 weeks after planting was not significantly different from the size at silking or harvest. Nitrogen fertilization significantly decreased the root : shoot weight ratio. However, tillage did not significantly change the ratio.

[29]

BENJAMIN J

, NIELSEN D

, VOGIL M

, CALDERON

. Water deficit stress effects on corn (Zea mays, L.) root﹕shoot ratio
Open Journal of Soil Science, 2014,4(4):151-160.

DOI:10.4236/ojss.2014.44018 URL [本文引用: 1]

[30]

GHEYSARI

, MIRLATIFI S

, BANNAYAN

, HOOGENBOOM

. Interaction of water and nitrogen on maize grown for silage
Agricultural Water Management, 2009,96(5):809-821.

DOI:10.1016/j.agwat.2008.11.003 URL [本文引用: 1]

Water scarcity and environmental pollution due to excessive nitrogen (N) applications are important environmental concerns. The Varamin region, which is located in the central part of Iran, is one of the locations where farmers apply 250 350 kg N ha 1 for silage maize without any concerns with respect to the available water for irrigation. The objective of this study was to quantify the response of the silage maize ( Zea mays L.) to variable irrigation and N fertilizer applications under arid and semi-arid conditions and to determine the optimum amount of N fertilizer as a function of irrigation. The maize Hybrid 704 single-cross was planted on 3 August 2003 and on 25 June 2004. The experimental treatments consisted of three N rates (0, 150, and 200 kg N ha 1) and four levels of irrigation, including two deficit irrigation levels 0.70 SWD (soil water depletion) and 0.85 SWD, a full-irrigation level (1.0 SWD) and an over-irrigation level (1.13 SWD). Twelve treatments were arranged in a strip-plot design in a randomized complete block with three replicates. Gravimetric soil samples were collected in 2003 and a neutron probe was used in 2004 to measure soil water content. Leaf area index, total aboveground biomass (TB), plant height, stem diameter, and leaf, stem, and ear dry weight were measured during the growing seasons and at final harvest. Total aboveground biomass was affected by irrigation ( P < 0.0001) during both years and was also affected by N fertilizer in 2003 ( P = 0.0001) and 2004 ( P < 0.0001). However, there was no irrigation and N fertilizer interaction for both years ( P > 0.5). Total aboveground biomass and biomass of the crop components increased as a function of the amount of water and N applied. For each of the irrigation levels, there was an associated optimum amount of N, which increased as the amount of irrigation water that was applied increased. Among the four irrigation levels that were studied, 0.85 SWD was the optimum level of irrigation for the conditions at the experimental site. The results also indicated that an increase in N applications is not a good strategy to compensate for a decrease of TB under drought stress conditions. We concluded that the effect of N fertilizer on TB depends on the availability of water in the soil, and that the amount of N fertilizer applied should be decreased under drought stress conditions. Further research will combine these results with a crop simulation model to help optimize nitrogen and water management for silage maize.

[31]

LYNCH J

. Root architecture and plant productivity
Plant Physiology, 1995,109(1):7-13.

DOI:10.1104/pp.109.1.7 URL [本文引用: 2]

[32]

LUNCH J

. Steep, cheap and deep: An ideotype to optimize water and N acquisition by maize root systems
Annals of Botany, 2013,112(2):347-357.

DOI:10.1093/aob/mcs293 URL [本文引用: 2]

http://aob.oxfordjournals.org/cgi/doi/10.1093/aob/mcs293

[33]

MI G

, CHEN F

, WU Q

, ZHANG F

. Ideotype root architecture for efficient nitrogen acquisition by maize in intensive cropping systems
Science China Life Sciences, 2010,53(12):1369-1373.

DOI:10.1007/s11427-010-4097-y URLPMID:21181338 [本文引用: 2]

The use of nitrogen(N) fertilizers has contributed to the production of a food supply sufficient for both animals and humans despite some negative environmental impact.Sustaining food production by increasing N use efficiency in intensive cropping systems has become a major concern for scientists,environmental groups,and agricultural policymakers worldwide.In high-yielding maize systems the major method of N loss is nitrate leaching.In this review paper,the characteristic of nitrate movement in the soil,N uptake by maize as well as the regulation of root growth by soil N availability are discussed.We suggest that an ideotype root architecture for efficient N acquisition in maize should include(i) deeper roots with high activity that are able to uptake nitrate before it moves downward into deep soil;(ii) vigorous lateral root growth under high N input conditions so as to increase spatial N availability in the soil;and(iii) strong response of lateral root growth to localized nitrogen supply so as to utilize unevenly distributed nitrate especially under limited N conditions.

[34]

, WHITE P

, HOCHHOLDINGRT

, LI C

. Phenotypic plasticity of the maize root system in response to heterogeneous nitrogen availability
Planta, 2014,240(4):667-678.

DOI:10.1007/s00425-014-2150-y URL [本文引用: 1]

[35]

SHARP R

, HSIAO T

, SILK W

. Growth of the maize primary root at low water potentials: II. Role of growth and deposition of hexose and potassium in osmotic adjustment
Plant physiology, 1990,93(4):1337-1346.

DOI:10.1104/pp.93.4.1337 URLPMID:16667622 [本文引用: 1]

Primary roots of maize (Zea mays L. cv WF9 x Mo17) seedlings growing in vermiculite at various water potentials exhibited substantial osmotic adjustment in the growing region. We have assessed quantitatively whether the osmotic adjustment was attributable to increased net solute deposition rates or to slower rates of water deposition associated with reduced volume expansion. Spatial distributions of total osmotica, soluble carbohydrates, potassium, and water were combined with published growth velocity distributions to calculate deposition rate profiles using the continuity equation. Low water potentials had no effect on the rate of total osmoticum deposition per unit length close to the apex, and caused decreased deposition rates in basal regions. However, rates of water deposition decreased more than osmoticum deposition. Consequently, osmoticum deposition rates per unit water volume were increased near the apex and osmotic potentials were lower throughout the growing region. Because the stressed roots were thinner, osmotic adjustment occurred without osmoticum accumulation per unit length. The effects of low water potential on hexose deposition were similar to those for total osmotica, and hexose made a major contribution to the osmotic adjustment in middle and basal regions. In contrast, potassium deposition decreased at low water potentials in close parallel with water deposition, and increases in potassium concentration were small. The results show that growth of the maize primary root at low water potentials involves a complex pattern of morphogenic and metabolic events. Although osmotic adjustment is largely the result of a greater inhibition of volume expansion and water deposition than solute deposition, the contrasting behavior of hexose and potassium deposition indicates that the adjustment is a highly regulated process.

[36]

TRACHSEL

, KAEPPLER S

, BROWM K

, LYNCH J

. Maize root growth angles become steeper under low N conditions
Field Crops Research, 2013,140:18-31.

DOI:10.1016/j.fcr.2012.09.010 URL [本文引用: 1]

Root traits that increase the speed and effectiveness of subsoil foraging may enhance nitrogen acquisition in leaching environments. We investigated root depth distribution of maize genotypes across the cropping cycle, effects of root angles on plant performance and potential plastic responses of root growth angles to nitrogen fertilization. We focus on genetic variation for growth angles of crown and brace roots among 108 inbred lines of maize in high and low nitrogen field environments in the USA and South Africa. Root angles of down roots were significantly associated with rooting depth calculated as the depth containing 95% of the root mass (D-95). The number of brace roots as well as rooting depth (D-95) increased between 43 days after planting (DAP) and flowering, but did not show any major changes between flowering and physiological maturity. Brace root branching increased between 43 DAP and flowering and showed reductions between flowering and physiological maturity. Under well-fertilized conditions genotypes initially selected as 'steep' and 'shallow' did not alter their root angles. Brace and crown root angles became up to 18 degrees steeper under nitrogen deficient conditions. Increases in root angles under nitrogen deficient conditions were more accentuated for shallow genotypes, resulting in root angles and rooting depths similar to the ones measured for steep genotypes. Steeper root angles enabled plastic genotypes to potentially explore similar soil volumes under nitrogen deficient conditions as steep genotypes, thereby not incurring any reductions in grain yield compared to genotypes constitutively forming steep root angles. Additive main and multiplicative interaction effects (AMMI) analysis revealed that out of 29 genotypes best adapted to 4 different nitrogen fertilizer treatment-by-location combinations, 11 were steep, 11 were plastic and 7 were shallow genotypes. The number of plastic genotypes among the adapted entries was disproportionately high compared to 6 that could be anticipated based on the distribution in the entire genotypic set. We postulate that modulation of rooting depth by root growth angles is important for nitrogen acquisition by positioning roots in soil domains with the greatest nitrogen availability. Genotypic variation in root growth angles and the plasticity of root growth angles in response to nitrogen may be useful in breeding crops with improved nitrogen acquisition. (C) 2012 Elsevier B.V. All rights reserved.

[37]

, CHEN

, WU

, MI G

. Genetic improvement of root growth increases maize yield via enhanced post-silking nitrogen uptake
European Journal of Agronomy, 2015,63:55-61.

DOI:10.1016/j.eja.2014.11.009 URL [本文引用: 2]

Root breeding has been proposed as a key factor in the “second green revolution” for increasing crop yield and the efficient use of nutrient and water resources. However, few studies have demonstrated that the genetic improvement of root characteristics directly contributes to enhancing nutrient-use-efficiency in crops. In this study, we evaluated the contribution of root growth improvement to efficient nitrogen (N) acquisition and grain yield under two different N-levels in a 3-year field experiment. We used two near-isogenic maize testcrosses, T-213 (large-root) and T-Wu312 (small-root), derived from a backcross of a BC4F3 population from two parents (Ye478 and Wu312) with contrasting root size. We found that the root length density, root surface area, and dry weight at the silking stage were 9.6–19.5% higher in T-213 compared with the control T-Wu312. The root distribution pattern in the soil profile showed no significant differences between the two genotypes. The overall increase in root growth in T-213 enhanced post-silking N uptake, which increased grain yield by 17.3%. Correspondingly, soil nitrate concentrations in the >30cm soil layer were reduced in T-213 under the high N treatment. These positive effects occurred under both adequate and inadequate N-supply and different weather conditions. Our study provides a successful case that increasing root size via genetic manipulation contributes directly to efficient N-uptake and higher yield.