水氮调控对小油菜养分吸收、水氮利用效率及产量的影响*

高 娜,张玉龙,刘 玉,廖常健,吴汉卿,张玉玲,邹洪涛,虞 娜

(沈阳农业大学土地与环境学院/发改委土肥资源高效利用国家工程实验室/农业部东北耕地保育重点实验室 沈阳 110866)

水氮调控对小油菜养分吸收、水氮利用效率及产量的影响*

高 娜,张玉龙,刘 玉,廖常健,吴汉卿,张玉玲,邹洪涛,虞 娜**

(沈阳农业大学土地与环境学院/发改委土肥资源高效利用国家工程实验室/农业部东北耕地保育重点实验室 沈阳 110866)

合理的灌水、施氮量对提高小油菜养分利用率、控制面源污染具有重要意义。本文采用盆栽试验,利用15N同位素示踪技术,研究不同灌水水平(W1:60%θf;W2:75%θf;W3:90%θf。θf为田间持水量)和施氮量(N0: 0 g∙kg-1;N1:0.1 g∙kg-1;N2:0.2 g∙kg-1;N3:0.3 g∙kg-1)对小油菜养分吸收、产量及水氮利用率的影响。结果表明:灌水水平与施氮量对小油菜根系与叶片氮、磷、钾含量均有显著影响,且叶片含磷量受水氮交互作用的显著影响。叶片氮、钾含量显著大于根系。增加灌水,小油菜含磷量与根系含氮量增加,含钾量及叶片含氮量降低;施氮能增加小油菜氮、钾含量,降低含磷量。灌水与施氮对小油菜氮、磷、钾吸收总量均有显著影响,且磷、钾吸收量受水氮交互作用的影响显著,中水低氮处理(W2N1)各养分吸收量均最大。小油菜产量受灌水水平和施氮量的显著影响,表现为随灌水水平的提高而增加,随施氮量的增加呈先增加后降低的趋势。灌溉水分利用效率(IWUE)受施氮量及水氮互作的显著影响,随施氮量增加,IWUE变化与产量变化一致。灌水与施氮对15N肥料去向有显著影响,且肥料利用率受水氮互作的显著影响。随灌水水平提高,肥料利用率呈增加趋势,中水处理肥料残留率最低,损失率最高。随施氮量增加,肥料利用率不断降低,损失率呈增加的趋势。本试验条件下,综合考虑小油菜养分吸收、产量及水氮利用率,W3N1、W2N1组合为推荐水氮处理。

小油菜;水氮调控;养分吸收;水分利用效率;氮肥利用率

我国设施蔬菜面积和产量居世界第一位[1],蔬菜生产已成为我国经济发展的重要组成部分。然而生产中,不合理的水肥管理导致水分与养分资源利用率降低[2],品质下降[3];氮素淋溶损失[4]及土壤面源污染[5]等问题频繁发生。水分与氮素之间存在耦合效应,共同影响作物的生长发育、产量及氮肥利用效率[6-7]。因此,有效调控设施蔬菜水氮供应,发挥水氮协同效应具有重要意义。国内外学者就水分、氮素对作物养分吸收、产量及水氮利用效率的影响做了大量研究。适当增加施氮量和灌水量有利于氮、磷、钾等养分的吸收[8-10],且氮、磷、钾的吸收量与作物干物质积累及产量呈显著正相关关系[11]。蔡树美等[12]对水肥优化耦合条件下设施青菜的研究表明,旺长期青菜体内氮磷钾含量、吸收速率和积累量显著大于幼苗期和成熟期。灌水量与施氮量对作物生产、产量均有显著影响[13],在一定范围内,产量与灌水量呈正相关关系,随施氮量的增加呈先增加后降低的趋势[14-15]。李静等[16]研究表明,黄瓜(Cucumis sativus)干物质积累量、灌溉水分利用效率、水分利用效率均受施氮量、灌水量及水氮交互作用(耦合效应)的显著或极显著影响。肖时运等[17]对莴苣(Asparagus lettuce)的研究表明,随施氮量的增加莴苣吸氮总量呈先增加后降低的趋势,氮肥利用率及氮肥残留率逐渐降低,而氮肥损失率不断增加。小油菜(Brassica campestris)是叶菜类的代表,营养丰富,复种指数高,有关水氮调控对其氮、磷、钾养分吸收及水氮利用效率的综合研究较少,其水氮耦合机制尚不明确。15N示踪技术是研究肥料利用率及去向的重要手段[18-19]。因此,本试验以小油菜为试材,采用15N示踪技术,研究不同灌水和施氮量对小油菜养分吸收、产量及水氮利用效率的影响,以期为小油菜高效生产提供理论依据。

1 材料与方法

1.1 试验地点与材料

试验于2014年9月在沈阳农业大学试验基地的日光温室内进行。选用上部内径24 cm,底部内径18 cm,高17 cm的盆钵进行土培试验,每盆装过3 mm筛的风干土4 kg。供试土壤类型为棕壤,采自露地菜田,有机质19.02 g∙kg-1,pH 5.95,全氮0.97 g∙kg-1,全磷0.41 g∙kg-1,全钾 22.24 g∙kg-1,碱解氮 83.07 mg∙kg-1,有效磷5.23 mg∙kg-1,速效钾80.36 mg∙kg-1,田间持水量为30.5%。供试小油菜为‘青帮白菜型油菜’。

1.2 试验设计及管理

试验采用3个灌水水平[分别为控制灌水上限60%θf(低水,W1)、75%θf(中水,W2)和90%θf(高水,W3),θf为田间持水量]和4个施氮量[0 g∙kg-1(无氮,N0)、0.1 g∙kg-1(低氮,N1)、0.2 g∙kg-1(中氮,N2)、0.3 g∙kg-1(常规施氮量,N3]的完全随机设计,共12个处理,3次重复。各处理磷钾用量相同,与土壤混合均匀后做基肥施入。磷肥为过磷酸钙,施用量为0.2 g(P2O5)∙kg-1,钾肥为硫酸钾,施用量为0.3 g(K2O)∙kg-1。试验所用氮肥为稳定性同位素15N标记的尿素(丰度20.14%,上海化工研究院),于播种前3 d以水溶液形式均匀施入土壤。小油菜于9月10日播种,9月17日出全苗后及时疏苗,长出真叶后每盆留苗8株。定苗前各处理灌水量一致,定苗后用称重法控制土壤相对含水量,每天调节土壤含水量1次,记录灌水量。

1.3 测定项目与方法

分别于小油菜4叶期(播种后28 d)与6叶期(播种后40 d)采收3棵和5棵。采下的植株立即将根系、叶片分开装入自封袋,带回实验室用清水洗净后用蒸馏水润洗2次,迅速用纱布擦干,以盆为单位迅速称重计产,产量Y(g∙pot-1)为两次总鲜重。记产后立即将样品于105℃下杀青30 min,在60℃下烘干粉碎。全氮和15N原子百分超用元素分析仪(VARIO ELⅢ, Germany)和稳定性同位素比例质谱仪(Isoprime 100, England)联用测定。植株磷钾含量用H2SO4-H2O2消煮后分别采用钼锑抗比色法、原子吸收法测定。

15N肥料利用效率(%)、15N肥料残留率(%)、15N肥料损失率(%)用以下公式计算[20-21]:

2 结果与分析

2.1 水氮调控对小油菜氮素吸收的影响

双因素方差分析表明,叶片与根的含氮量均受灌水水平和施氮量单一效应的显著影响,且叶片含氮量大于根系(表1)。W1灌水水平叶片含氮量显著大于W2和W3,W2与W3间差异不显著;W3处理根系含氮量显著高于其余2个处理,W1与W2差异不显著。施氮能显著提高小油菜叶片与根系含氮量,而各施氮处理间差异不显著。

施氮量对小油菜叶片、根系及整株吸氮量均有显著影响,均表现为N1、N2>N3>N0,即适量施氮有利于小油菜氮素吸收。灌水水平仅对小油菜根系吸氮量有显著影响,表现为W3、W2>W1。

2.2 水氮调控对小油菜磷素吸收的影响

由表2可知,灌水量和施氮量对小油菜叶片与根系含磷量均有显著影响,且叶片含磷量受水氮交互作用的显著影响。小油菜叶片与根系含磷量随灌水水平的提高而降低;不施氮处理叶片含磷量显著高于施氮处理,而各施氮处理间差异不显著;N3处理根含磷量最大,N2处理含磷量最小,二者差异达显著水平。水氮交互作用下,W3灌水水平下的各施氮处理叶片含磷量差异达显著水平,而W1、W2灌水水平下各施氮处理差异不显著。

双因素方差分析表明,灌水水平、施氮量及水氮互作对小油菜整株与叶片吸磷量均有显著影响,表现为水分>水氮交互>施氮量。灌水对小油菜吸磷量的影响表现为W2>W1>W3;N1、N2处理小油菜吸磷量最大且差异不显著,但均显著大于N3处理。水氮交互作用下,W2N1处理吸磷量最大,其次为W1N2处理,W3N1与W3N3处理最小。

2.3 水氮调控对小油菜钾素吸收的影响

由表3可知,小油菜叶片含钾量约为根的2倍,且受灌水水平和施氮量的显著影响。W1处理叶片与根含钾量均显著大于W2、W3处理,且W2与W3差异不显著,即灌水量较低时小油菜含钾量较大。随施氮量增加,小油菜叶片与根中含钾量均呈增加的趋势。

双因素方差分析表明,小油菜叶片、根及整株吸钾量均受施氮量和水氮交互作用的显著影响,灌水水平对小油菜吸钾量影响不显著。施氮量对小油菜叶片及整株吸钾量的影响均表现为N1>N2>N3>N0,对根吸钾量的影响表现为N2>N1>N0>N3,即适量施氮有利于小油菜对钾的积累。水氮交互作用下, W2N1处理小油菜叶片及整株吸钾量均为最大且显著大于其他处理,W2N2处理根吸钾量最大。

2.4 水氮调控对小油菜产量、灌溉水分利用效率及肥料去向的影响

方差分析可知,灌水水平与施氮量对小油菜产量的影响均达到极显著水平,而水氮交互作用不显

著(表4)。小油菜产量随灌水水平的提高而增加,W2与W3差异不显著;但随施氮量的增加呈先增加后降低的趋势,N1与N2施氮量间差异不显著。

表1 水氮调控对小油菜不同器官氮素吸收的影响Table 1 Regulation effects of different irrigation levels and nitrogen fertilization rates on nitrogen uptake of rape

表2 水氮调控对小油菜不同器官磷素吸收的影响Table 2 Regulation effects of different irrigation levels and nitrogen fertilization rates on phosphorus uptake of rape

表3 水氮调控对小油菜不同器官钾素吸收的影响Table 3 Regulation effects of different irrigation levels and nitrogen fertilization rates on potassium uptake of rape

施氮量对小油菜灌溉水分利用效率(IWUE)具有极显著影响,且水氮交互作用显著(表4)。小油菜IWUE随施氮量的增加呈先增加后降低的趋势,N1与N2差异不显著。水氮交互作用下,W1N1处理IWUE最大,分别与W3N2、W1N2、W2N1、W2N2、W3N1、W2N3处理差异不显著;W3N3处理IWUE最小,其次为W1N0和W2N0处理。

不同水氮处理下15N肥料在土壤-作物系统中的去向研究表明,水分与氮素对15N肥料去向有显著影响。随灌水水平的提高,15N肥料利用率呈增加的趋势,W2处理肥料残留率最低,损失率最高。随施氮量的增加,肥料利用率呈降低的趋势,而肥料损失率呈增加的趋势,残留率变化不显著。水氮互作对肥料利用率有显著影响。W3N1处理氮肥利用率最大,为23.00%,其次为W2N1处理,为18.41%,W1N3处理最小,仅为5.30%。W3N1处理肥料利用率最高,损失率最低,而残留率适中,考虑肥料利用情况为最佳水氮处理。此外,W2N1处理有较高的肥料利用率及较低的残留率与损失率(表4)。

3 讨论

植物叶片与根系间养分含量靠浓度梯度在体内运输[22],因而,根系与叶片养分含量有显著相关性,但不同时期表现不同[23]。本试验中叶片氮、钾含量显著大于根系,这是由于采收时小油菜叶片光合作用旺盛,需要大量养分供应,因而养分更多地从根系转移到叶片中[23]。此外,本试验表明不同水氮处理养分积累量与养分含量相关性不显著,而与产量呈正相关关系(吸磷量除外),这与前人研究一致[11]。施氮能增加植株对氮、磷、钾的吸收,而过量施氮吸收量反而降低,这在水稻(Oryza sativa)、玉米(Zea mays)、甜瓜(Cucumis melo)、棉花(Gossypiumsp.)等植株上已得到验证[9-10]。本试验中,施氮量超过0.1 g∙kg-1(土),小油菜对氮、磷、钾的吸收增加不显著甚至有降低的趋势。这是由于过高的氮肥会对作物产生毒害作用,抑制植株正常生长及对养分的吸收[24]。灌水水平对磷的吸收也有显著影响,W2处理磷吸收量最大,而对氮、钾的吸收量影响不显著。此外,水氮耦合效应对磷、钾的积累量有显著影响。合理调控水氮供应能提高小油菜养分吸收积累,W2N1处理(75%θf,0.1 g∙kg-1)植株氮、磷、钾养分吸收量均为最大。

表4 水氮调控对小油菜产量、灌溉水分利用效率及15N肥料在土壤-作物系统中去向的影响Table 4 Regulation effects of different irrigation levels and nitrogen fertilization rates on yield,irrigation water use efficiency and fate of15N-labelled fertilizer in soil and crop system

小油菜产量与水氮供应及水氮利用效率密切相关。本试验中小油菜产量随灌水水平的提高而增加,随施氮量的增加呈先增加后降低的趋势,这与Badr等[15]的研究一致。此外,产量与IWUE及氮肥利用效率呈正相关关系(P<0.05,数据未列出),这是由于较高的水分、养分吸收能为叶片光合作用提供充足的原料,增加光合同化产物,促进小油菜产量的提高。

灌水与施氮量均能影响作物IWUE,研究表明IWUE与灌水量呈显著负相关关系,施用氮肥能提高IWUE[3,17]。本试验中不同灌溉水平IWUE差异不显著,而灌水量对IWUE影响极显著。这可能是由于低灌水量产生水分胁迫,抑制了小油菜生物量的生长,因而IWUE较低。适当提高灌水量,能保证小油菜生长所需水分,保持适当的土壤孔隙度,减少土壤表面水分蒸发,提高灌溉水分利用率。这也与邓忠等[25]、Cabello等[26]的研究结果一致。本试验中IWUE随施氮量的增加呈先增加后降低的趋势,回归分析得出,施氮量为0.16 g∙kg-1时IWUE最大。设施菜地施入土壤中的肥料除部分被作物吸收和损失外,大部分残留在土壤中,对环境构成潜在威胁。本试验中不同水氮处理15N 肥料利用率为5.30%～23.00%,残留率为56.22%～71.29%,损失率为13.17%～37.10%,这与设施蔬菜及露天菜地的研究结果相近[19,27-28],但低于谷类作物[29]。一方面蔬菜较低的肥料利用率是由于蔬菜与谷类作物相比植株较小,对肥料的吸收量也较少,而实际施肥量却较高;另一方面本试验所用肥料为一次性基施,肥料利用率低于多次追施[30-32]。本试验中,小油菜15N肥料利用率随灌水水平的提高而增加,随施氮量的增加而降低,这与前人研究相一致[17,33]。

综上所述,适当增加灌水和适宜的施氮量能增加小油菜对氮、磷、钾的吸收量,提高产量和水氮利用效率,本试验条件下W3N1与W2N1为推荐水氮处理。尽管盆栽试验与实际生产存在一定差异,本试验的研究结果对进一步开展田间试验及生产管理具有一定指导意义。

4 结论

不同灌水水平、施氮量及水氮互作对小油菜氮、磷、钾养分含量及吸收量影响各异,W2N1处理(75%θf,0.1 g∙kg-1)小油菜对氮、磷、钾养分吸收量均为最大。小油菜产量受灌水水平和施氮量的显著影响,表现为随灌水水平的提高而增加,随施氮量的增加呈先增加后降低的趋势。灌溉水分利用效率(IWUE)受施氮量及水氮互作的显著影响,IWUE随施氮量增加,其变化与产量变化一致。15N肥利用率随施氮量增加而降低,随灌水水平的提高而增大,W3N1处理(90%θf,0.1 g∙kg-1)15N肥利用率最高,损失率最低。综合考虑小油菜养分吸收、产量及肥料去向,W3N1、W2N1为推荐水氮处理。

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Regulation effects of irrigation and nitrogen fertilization on nutrient absorption,water/nitrogen use efficiency and yield of rape*

GAO Na,ZHANG Yulong,LIU Yu,LIAO Changjian,WU Hanqing, ZHANG Yuling,ZOU Hongtao,YU Na**
(College of Land and Environment,Shenyang Agricultural University/National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resource/Northeast Key Laboratory of Conservation and Improvement of Cultivated Land,Ministry of Agriculture,Shenyang 110866,China)

Excessive fertilizer and irrigation are often used in greenhouse cultivation in order to ensure adequate and pro fi table yieldof vegetables.This has led to the pollution of agricultural environment that in turn hindered sustainable agricultural development. Reasonable application of irrigation and nitrogen is vital for enhancing nutrient use efficiency and controlling non-point source pollution.Using a stable isotope of15N-traced urea,a pot experiment was conducted to evaluate the effects of different irrigation and nitrogen applications on nutrient absorption,water/nitrogen utilization and yield of rape.The study included three irrigation levels [W1,60%θf(field capacity);W2,75%θf;and W3,90%θf]and four nitrogen rates(N0,0 g∙kg-1;N1,0.1 g∙kg-1;N2,0.2 g∙kg-1;and N3,0.3 g∙kg-1).The contents and absorptions of nitrogen,phosphorus and potassium by different parts of rape plant were determined along with water and nitrogen use efficiencies.The results suggested that both irrigation level and nitrogen application rate had significant effects on contents of N,P,K in the leaves and roots of rape plants.Besides,leaf P content was significantly affected by the interaction of irrigation and nitrogen.The contents of N and K in the leaves were much higher than those in the roots.While the content of P in the whole rape plant and N in the roots increased,the content of K in the whole plant and N in the leaf decreased with increasing irrigation.N application increased plant N and K contents,but reduced P content.There were significant effects of irrigation level and nitrogen rate on N,P and K uptake and the interaction effects were also prominent for P and K absorption.Medium irrigation level and low nitrogen rate(W2N1)had the highest nutrient uptake.The yield of rape was significantly affected by irrigation level and nitrogen rate.Yield increased with increasing irrigation level and a significant parabolic relationship was observed between nitrogen rate and yield.The application rate of nitrogen and the interaction of irrigation and nitrogen had a significant effect on irrigation water use efficiency(IWUE).Also the response of yield in terms of IWUE increased with increasing nitrogen application.Both irrigation and nitrogen fertilizer had significant effects on the utilization of fertilizer15N.Besides,a statistically significant interaction was noted between water and nitrogen in terms of nitrogen recovery rate. Fertilizer15N recovery rate increased with increasing irrigation level.The rates of15N residue and15N loss were respectively lowest and highest under medium irrigation level.With increasing nitrogen does,fertilizer recovery rate gradually decreased and the loss rate increased.It was concluded that for comprehensive nutrient uptake,yield output,and water and nitrogen utilization, W3N1and W2N1treatments were the best.

Rape;Water-nitrogen regulation;Nutrient absorption;Water use efficiency;Nitrogen use efficiency

Nov.12,2016;accepted Dec.29,2016

S634.3;S635

A

1671-3990(2017)06-0821-08

10.13930/j.cnki.cjea.161009

高娜,张玉龙,刘玉,廖常健,吴汉卿,张玉玲,邹洪涛,虞娜.水氮调控对小油菜养分吸收、水氮利用效率及产量的影响[J].中国生态农业学报,2017,25(6):821-828

Gao N,Zhang Y L,Liu Y,Liao C J,Wu H Q,Zhang Y L,Zou H T,Yu N.Regulation effects of irrigation and nitrogen fertilization on nutrient absorption,water/nitrogen use efficiency and yield of rape[J].Chinese Journal of Eco-Agriculture, 2017,25(6):821-828

* 国家自然科学基金项目(41401322)、国家科技支撑计划项目(2015BAD23B01-6)和农业部东北耕地保育重点实验室开放基金(2015NYBKFT-01)资助

**通讯作者:虞娜,主要从事土壤改良与农业节水研究。E-mail:sausoilyn@163.com

高娜,主要从事土壤改良与农业节水研究。E-mail:807844798@qq.com

2016-11-12 接受日期:2016-12-29

* The study was supported by the National Natural Science Foundation of China(41401322),the National Key Technology R&D Program of China(2015BAD23B01-6)and the Open Fund of Key Laboratory of Arable Land Conservation Foundation,Ministry of Agriculture of China (2015NYBKFT-01).

**Corresponding author,E-mail:sausoilyn@163.com