刘小宁, 刘海坤, 黄玉芳, 叶优良

(河南农业大学资源与环境学院，郑州 450002)

施氮量、土壤和植株氮浓度与小麦赤霉病的关系

刘小宁, 刘海坤, 黄玉芳, 叶优良*

(河南农业大学资源与环境学院，郑州 450002)

小麦； 赤霉病； 植株氮浓度； 土壤硝态氮； 施氮量

小麦遭到赤霉病病菌侵染后穗部出现红色霉状物[1]，故称赤霉病，是由多种镰刀菌引起的真菌病害[2-3]，其在高温、高湿条件下发病严重，尤其在小麦抽穗扬花期的气象条件对小麦赤霉病的发生有重要影响，为典型气候型病害[1,4]。前人对小麦赤霉病发生的原因、特点及防治措施做了大量研究[5-9]。近年来，有关施用氮肥对小麦赤霉病影响的研究逐渐增多[10-11]，乔玉强等指出施氮增加了小麦赤霉病病穗率和病情指数[11]，高量施氮条件下赤霉病发病程度和籽粒毒素含量维持在较高水平[12]；Jensen和Munk的研究表明，氮肥用量的增加使菌落密度增大[13]，低氮条件下菌落形成会减少，病菌侵染能力降低[14]。

施氮增加了土壤中硝态氮的累积和植株的氮浓度[15]，硝态氮反映了土壤供氮能力[16]，其含量制约着小麦氮素的吸收[17]。植株全氮和茎基部硝酸盐可以作为植株氮素营养诊断的指标，反映小麦植株氮素营养状况[18]，茎基部硝酸盐比全氮能更直接快速地反映小麦植株的氮素营养状况[19]。Delin等指出发病率低的小麦植株含氮量增加，土壤硝态氮累积量减少。发病率降低后增加了小麦对氮素的吸收，减少了收获后土壤硝态氮的残留[20]。但有关土壤硝态氮和小麦植株氮素营养对小麦病害影响的研究相对较少。2012年4月下旬和5月上旬小麦正值抽穗扬花期，遇到了连续高温阴雨天气，为赤霉病传播创造了气候条件，导致赤霉病在全国普遍发生，河南省的发病尤其严重[21]，发病面积约为57.8%，平均病穗率10%左右[22]。为了深入了解施氮量对土壤硝态氮、植株氮浓度和赤霉病的影响及土壤硝态氮、氮浓度与赤霉病的关系，对不同施氮量下两个品种小麦赤霉病的发病情况进行了调查和分析，旨在为小麦生产中病害的防治提供依据。

1 材料与方法

1.1 试验地概况

1.2 试验设计

供试品种为当地主栽品种多穗型豫麦49-198(YM49-198)和大穗型周麦16(ZM16)。试验设N 0、120、180、240、360 kg/hm25个施氮水平，分别用N0、N120、N180、N240、N360表示。氮肥为尿素(含氮46%)，1/2氮肥在小麦播前作基肥施入，1/2在小麦拔节期追施。磷、钾肥全部基施，磷肥为过磷酸钙(含P2O512%)，用量为90 kg/hm2，钾肥为氯化钾(含K2O 60%)，用量为90 kg/hm2。小区面积48 m2，重复3次，随机区组排列。豫麦49-198的播量为150 kg/hm2，周麦16播量为195 kg/hm2，2011年10月17日播种，2012年6月5日收获。田间管理按照当地高产模式进行管理。

1.3 测定项目及方法

1.3.1 土壤硝态氮 在小麦越冬、返青、拔节、开花和成熟期每个小区分别采取一组0—30 cm、30—60 cm和60—90 cm土层土壤，鲜样经0.0l mol/L CaCl2浸提，流动分析仪测定土壤硝态氮含量。同时另取一份土壤烘干后测定土壤含水量。

1.3.2 植株全氮 在小麦越冬、返青、拔节、开花、收获期每个小区随机采取20株小麦植株样品，105°C杀青，75°C烘干后粉碎，半微量凯氏定氮法测定小麦整株的植株全氮含量。

1.4 数据处理

试验数据采用Excel 2010和SPSS 20.0进行处理，用Duncan法进行处理间多重比较，各变量之间使用Pearson相关系数法进行相关分析[25]；采用OriginPro 8.1绘图。

2 结果与分析

2.1 施氮对小麦土壤硝态氮的影响

2.1.1 对土壤硝态氮含量的影响 从表1可以看出，小麦各土层硝态氮含量随施氮量的增加而增加。越冬期30—60 cm、 60—90 cm土层硝态氮含量高于0—30 cm，其他时期0—30 cm硝态氮含量明显高于30—60 cm和 60—90 cm。在拔节期，两个品种N0、N120、N180、N240处理的硝态氮含量在0—30 cm土层差异不显著；开花期和收获期两个小麦品种0—30 cm土层的硝态氮含量N0、N120、N180处理最低且无显著差异，N240、N360处理的差异不显著但显著高于其他处理。

2.1.2 对土壤硝态氮累积量的影响 小麦不同生育期0—90 cm土层土壤硝态氮累积量随施氮量的增加而增加，不同施氮水平间差异显著(表2)。拔节期0—90 cm土层硝态氮累积量最低。开花期和收获期两个品种N0、N120、N180处理0—90 cm土层硝态氮累积量最低，且三者之间差异不显著，但显著低于N360处理。

2.2 施氮对小麦植株氮浓度的影响

表1 施氮对不同小麦品种各土层土壤硝态氮含量的影响(mg/kg)

注(Note): 同列数据后不同字母表示处理间差异达5%显著水平 Values followed by different letters in a column are significant different among treatments at the 5% level.

2.2.3 施氮量与植株氮浓度的相关性 相关分析(表4)表明，施氮量与小麦植株全氮含量呈正相关，尤其在小麦拔节期 (r=0.932**、r= 0.740**)和开花期(r=0.895**、r= 0.907**)，两者的相关性达到极显著水平，与小麦抽穗期、开花期和灌浆期茎基部硝酸盐含量也呈显著正相关关系。

2.3 施氮对小麦赤霉病发病率和病情指数的影响

表2 施氮对不同小麦品种0—90 cm土层土壤硝态氮累积的影响(kg/hm2)

注(Note): 同列数据后不同字母表示处理间差异达5%显著水平 Values followed by different letters in a column are significant different among treatments at the 5% level.

表3 施氮对小麦各生育期植株茎基部硝酸盐含量的影响(mg/L)

注(Note): 同列数据后不同字母表示处理间差异达5%显著水平 Values followed by different letters in a column are significant different among treatments at the 5% level.

表4 施氮量与小麦植株氮浓度的相关性

注(Note): WN—越冬期全氮Wintering N; RN—返青期全氮Returnning N; JN—拔节期全氮Jointing N; AN—开花期全氮Anthesis N; BSN—孕穗期茎基硝酸盐Stem sap nitrate at the booting, ASN—开花期茎基部硝酸盐Stem sap nitrate at the anthesis, FSN—灌浆期茎基部硝酸盐Stem sap nitrate at the filling.*,**分别表示5%和1%显著水平Indicate significant differences at the 5% and 1% levels, respectively.

相关分析(表5)表明，施氮量与豫麦49-198和周麦16的赤霉病病穗率和病情指数呈极显著的正相关，相关系数分别为0.856、0.913和0.907、0.956。

图1 不同施氮量小麦植株各生育期全氮含量的变化Fig.1 Changes of total nitrogen content of the nitrogen application in wheat plants at different growth stages

图2 施氮对小麦赤霉病病穗率和病情指数的影响Fig.2 Effects of the nitrogen application on morbidity and disease index (DI) of wheat scab[注(Note)： 柱上不同字母表示处理间差异达5% Different letters above the bars mean significant among treatments at the 5% level.]

品种Cultivar病穗率Morbidity病情指数Diseaseindex豫麦49-198YM49-1980．856∗∗0．907∗∗周麦16ZM160．913∗∗0．956∗∗

注(Note): **表示1%显著水平Indicate significant differences at the 1% level.

2.4 土壤硝态氮、植株氮浓度与小麦赤霉病的关系

土壤硝态氮含量与赤霉病病穗率和病情指数呈正相关(表6)，0—30 cm、 30—60 cm、 60—90 cm土层土壤的硝态氮含量与病穗率和病情指数相关性在越冬期最高，豫麦49-198各土层与病穗率的相关系数分别为0.840、0.869、0.797，与病情指数的相关系数分别为0.877、0.926、0.894；周麦16各土层与病穗率的相关系数分别为0.881、0.940、0.909，与病情指数的相关系数分别为0.954、0.950、0.846。两个品种小麦0—30 cm和30—60 cm土层硝态氮含量与病穗率和病情指数的相关性在小麦生育期内呈“先降低后增加”趋势，0—30 cm的相关性在拔节期最低，30—60 cm的相关性在开花期最低；60—90 cm的硝态氮含量与赤霉病的相关性，豫麦49-198在收获期最低，周麦16在拔节期和开花期最低。

表6 土壤硝态氮含量与小麦赤霉病病穗率和病情指数的相关性

注(Note): *,**分别表示5%和1%显著水平Indicate significant differences at the 5% and 1% levels, respectively.

表7表明小麦各生育期0—90 cm土层的硝态氮累积量与小麦赤霉病病穗率和病情指数呈线性正相关，拟合度呈“先降低后增加”趋势，越冬期最高，拔节期最低，与0—90 cm土层的硝态氮累积量变化趋势一致。小麦赤霉病易感期即开花期0—90 cm土层的硝态氮累积量与赤霉病病穗率和病情指数存在显著线性正相关关系，说明开花期土壤硝态氮累积量增加会加重小麦赤霉病。收获期0—90 cm土层硝态氮累积量与赤霉病病穗率和病情指数也存在显著正相关关系，小麦发生赤霉病后可能降低了小麦对土壤氮素的吸收、 利用，从而导致土壤中大量的硝态氮残留。

小麦拔节期、开花期植株全氮含量和孕穗期、开花期、灌浆期茎基部硝酸盐含量与小麦赤霉病病穗率和病情指数线性呈正相关(图3、图4)。两个品种小麦在拔节期和开花期的植株全氮含量与赤霉病病穗率和病情指数的拟合性均达到显著水平，开花期的拟合相关性大于拔节期(图3)。说明小麦开花期植株全氮含量的增加可能会加重小麦赤霉病。

小麦赤霉病病穗率和病情指数随茎基部硝酸盐含量的增加而增加(图4)，孕穗期、开花期和灌浆期茎基部硝酸盐含量与赤霉病病穗率和病情指数的拟合均达到显著水平，豫麦49-198的孕穗期茎基部硝酸盐含量与病穗率和病情指数的拟合相关性最大，周麦16在开花期的拟合最好，灌浆期最差。植株全氮含量和茎基部硝酸盐含量增加均会加重小麦赤霉病，说明小麦赤霉病易感期植株的氮素营养状况会影响赤霉病的发病程度。

表7 0—90 cm小麦土壤硝态氮累积量与小麦赤霉病的关系

注(Note): *,**分别表示达5%和1%显著水平Indicate significant differences at the 5% and 1% levels, respectively.

图3 植株全氮含量与小麦赤霉病的关系Fig.3 Relationship between the plant total nitrogen content and wheat scab [注(Note)： **表示达1%显著水平Indicate significant difference at the 1% levels.]

图4 茎基部硝酸盐含量与小麦赤霉病的关系Fig.4 Relationships between the stem base nitrate and wheat scab [注(Note)： BSN—孕穗期茎基部硝酸盐Stem sap nitrate at the booting; ASN—开花期茎基部硝酸盐Stem sap nitrate at the anthesis; FSN—灌浆期茎基部硝酸盐Stem sap nitrate at the filling; DI—病情指数 Disease index. *,**分别表示达5%和1%显著水平Indicate significant differences at the 5% and 1% levels,respectively.]

3 讨论

氮素与作物病害方面前人做了大量研究，有研究指出施氮会加重小麦白粉病和壳针孢叶斑病[26]病害，还可使魔芋[27]和烟草赤星病[28]、黑胫病[29]发病率增加；Hoffland等研究指出，番茄叶片氮浓度与病原菌感病性显著正相关[30]；金霞等指出烟叶中氮含量与赤星病发病率和病情指数显著正相关[28]。说明施氮量及氮浓度增加了菌落密度，使病原菌感病力增强，在作物感病期明显表现出发病症状。本研究表明，小麦拔节期、开花期的植株全氮含量和抽穗期、开花期以及灌浆期茎基部的硝酸盐含量与小麦赤霉病病穗率和病情指数呈显著线性正相关，与前人研究的氮含量与病害关系的结果相似。小麦赤霉病是典型气候型病害，气候是导致小麦赤霉病发生的直接因素[31]，但是影响其发病严重程度的因素有很多，耕作制度[32]、品种、播量、播种日期、杀菌剂的使用、施肥[8-11]等。研究指出前茬作物为玉米的地块更有利于引发赤霉病的镰刀菌接种和繁殖[32]，小麦在抽穗扬花期大量孢子存在情况下若遇到连续阴雨天气极易导致赤霉病的发生，因为该时期小麦花药可以诱导病菌孢子生长[33]，高温高湿的气候条件加速了病菌的传播[31]。不同施氮量和氮浓度条件下赤霉病的发病程度的不同可能是不同施氮量和氮浓度环境下形成的镰刀菌菌落大小和密度的不同造成的。余洪菊[10]研究表明，相同施氮量下加大前期氮肥投入量可以降低小麦赤霉病的发病率，相同基追比条件下拔节期追肥的赤霉病发病最重，孕穗期和返青期较轻，说明不同氮肥运筹会影响赤霉病的发病程度。

4 结论

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Relationships between nitrogen application rate soil nitrate-nitrogen, plant nitrogen concentration and wheat scab

LIU Xiao-ning， LIU Hai-kun， HUANG Yu-fang， YE You-liang*

(CollegeofResourcesandEnvironment,HenanAgriculturalUniversity,Zhengzhou450002,China)

【Objectives】 Scab has become one of the major diseases affecting yield and quality of wheat. An experiment was set up to study effect of nitrogen fertilization on wheat scab and to explore relations between nitrogen fertilizer and soil nitrogen, plant nitrogen concentration and wheat scab under different nitrogen levels. 【Methods】 A field experiment was conducted using 5 nitrogen rates (N 0, 120, 180, 240 and 360 kg/ha) and a multi-spike wheat cultivar YuMai49-198(YM49-198) and a large spike wheat cultivar ZhouMai16 (ZM16) in randomized blocked, and wheat scab was investigated by “wheat scab forecasting technical specifications”. 【Results】 The soil nitrate nitrogen contents and accumulation amounts in 0-90 cm soil layer are increased with the increase of N application rate. There are no significant differences in soil nitrate nitrogen contents at 0-30 cm and the accumulation amounts in 0-90 cm soil layer under N0, N120and N180, and the contents and amounts are significantly lower than those under N240and N360at the maturity. The morbidities and disease index(DI) of wheat scab are increased with the increase of N application rate, and there are significantly differences among different treatments. The morbidities and DIs of YM49-198 under the N treatments are higher than those under the N0treatment by 29.5%-132.0% and 35.9%-225.2%, respectively, and those of ZM16 are 42.4%-161.8% and 41.7%-206.9%. The morbidities and DIs of the two wheat cultivars under N0, N120and N180are not significant different, and are significantly lower than those under N240and N360. However, the disease of ZM16 is more serious since the morbidities and DIs are higher than those of YM49-198 by 7%-25% and 28.0%-63.6%, respectively. The scab morbidity and DI are positively correlated with soil nitrate content, and linearly correlated with nitrate-nitrogen accumulation in 0-90 cm. The stem sap nitrate concentrations at the booting, anthesis and filling stages, the total nitrogen contents at the jointing and anthesis stages have significant differences among the treatments, and are significantly and positively linear correlated with the scab morbidity and DI. 【Conclusions】 The soil nitrate nitrogen contents and accumulation amounts are increased with the increase of the N application rate. The soil residual nitrate is lower under conditions of nitrogen rate less than 180 kg/ha, and thus, the scab disease is lighter. The morbidity and DI of wheat scab are increased with the N application rate, which illustrates that higher nitrogen fertilizer will aggravate wheat scab disease at the jointing and anthesis stages. Therefore, to reducing the scab disease, appropriate nitrogen rate, soil nitrate and plant nitrogen concentration are needed during this period. Considering the residual nitrate in soil, the yield and scab, the appropriate nitrogen amount is N 180 kg/ha.

winter wheat; wheat scab; plant nitrogen concentration; soil nitrate-nitrogen; nitrogen rate

2014-03-04 接受日期： 2014-06-23

农业部公益性行业专项(201103003)；国家自然科学基金项目(31471935)；国家“973”项目(2009CB11866)资助。

刘小宁(1987—)，女，河南安阳人，硕士研究生，主要从事氮素养分资源综合管理研究。E-mail: LXN409@126.com * 通信作者 E-mail: ylye2004@163.com

S435.121.4+5； S512.1.062

A

1008-505X(2015)02-0306-12