钾肥运筹对砂泥田土壤烤烟生长、钾素吸收及香气品质改善的影响

张士荣1,王 军2,林昌华3,丁效东1

(1.青岛农业大学 资源与环境学院,山东 青岛 266109;2.广东省烟草南雄科学研究所,广东烟草粤北烟叶生产技术中心,广东 南雄 512400;3.韶关学院 英东农业科学与工程学院,广东 韶关 512005)

摘要:探究了华南砂泥田土壤有机肥C/N优化下钾肥用量和基追比对烤烟生物量、钾素吸收、土壤有效钾含量及香气品质改善的影响。采用裂区设计,主处理为3个施钾水平,K1(120.0 kg/hm2)、K2(240.0 kg/hm2)和K3(360.0 kg/hm2);副处理为钾肥不同基追比:S1(7∶3)、S2(5∶5)和S3(3∶7)。结果表明:旺长期-成熟期烟叶生物量随施钾量增加而提高,而随钾追肥比例增加,烟叶生物量降低;K2和K3水平下,基追比S1处理成熟期上部烟叶钾离子含量低,但基追比S2和S3处理上部烟叶钾供应充足,表明钾肥后移有利于钾离子从下部叶向中、上部叶转移。随施钾量提高,根际土壤速效钾和缓效钾含量增加;K2水平旺长期、现蕾期根际土壤速效钾含量最高,成熟期时S3基追比处理低于基追比S1和S2处理;K3水平下,根际土壤速效钾在4个生育期内无显著差异。与其他处理相比,K2水平S3处理显著增加烟叶总氮、总烟碱和蛋白质含量,改善糖碱比和氮碱比。K1水平上部叶中性致香物质含量在不同基追比间无显著差异;而K2、K3水平下,基追比S3处理显著提高烟叶(特别上部烟叶)中性致香物质含量,尤其是K2水平下,基追比S3处理烟叶香气质、香气量、浓度最优,劲头适中。综上所述,有机肥C/N优化条件下,华南砂泥田土壤钾肥推荐量为240.0 kg/hm2,其中基肥(移栽前条施后覆膜)72.0 kg/hm2,追肥168.0 kg/hm2(基追比为3∶7),能够有效提高烟叶钾离子含量,并改善烟叶尤其是上部烟叶的品质。

关键词:烤烟;钾肥;砂泥田土壤;基追比;供钾能力;品质指标;香气成分

烟草(Nicotiana tabacum L.)是需钾量较高的叶用经济作物,生产100 kg烟叶所需要的氮、磷、钾养分量为:氮(N)3.5 kg、磷(P2O5)0.6 kg、钾(K2O)7.5 kg[1]。充足的钾素供应是获得优质适产烟叶的重要条件,然而我国生产的烟叶钾素含量平均小于2.0%,低于国际优质烟叶钾含量不低于2.5%的标准,烟叶含钾量的提高成为改善我国烤烟质量的关键措施[2]。针对我国土壤含钾量不高的情况,合理增施钾肥是生产优质烟叶不可缺少的重要措施,优质烤烟对钾素的需求是团棵期-旺长期钾素需求量少,成熟期需钾较多[3]。在我国南方,1∶1型黏土矿物土壤对钾素固定能力较低,但频繁降雨造成土壤钾素淋失,加之打顶导致烟株根系活力下降,烟株体内钾含量降低,叶片由钾素输入库变成钾素输出源,直接导致烟叶钾含量降低,若不追施钾肥,将造成烟株生长缓慢,叶尖、叶缘处出现红褐色枯斑,单位面积叶片质量降低,叶片粗糙变薄,导致上部烟叶可用性及品质下降[3-4]

我国烤烟钾肥施用以基肥为主,仅在移栽时穴施少量钾肥或移栽15 d后追施1/3左右钾肥[5]。烟株吸钾速率在旺长期最高。Marchand等[6]研究发现,钾肥分次施用特别是生长后期供应充足时,对提高烟叶含钾量至关重要。Patel[7]研究发现,烟叶对钾的积累主要在烟草移栽后60 d或90 d。因此,在烤烟生育后期追施钾肥可显著提高烟叶含钾量和烤烟品质。有研究表明,烟叶产量主要取决于生长前期供钾,而烟叶钾含量的高低主要受生育后期供钾充足与否的影响[8]。烟叶钾含量高不仅使烟叶可溶性糖含量上升,还可以缩减可溶性糖与还原糖差值,而烟叶还原糖含量提高,可以提高烟叶烟气柔细度和香气质,降低蛋白质燃烧所产生的不良气味[8]

华南砂泥田土壤是我国烟草重要种植区,近年来烤烟种植集约化程度不断提高,造成土壤板结、酸化、微生物区系紊乱,导致土壤理化性质恶化问题尤为严重。前期研究发现,饼肥与化肥配施可以显著提高烟区土壤微生物量碳含量、腐殖酸总碳量和土壤酶活性,降低烤烟刺激性,改善烤烟香气质,提高香气量[9]。而土壤酶活性与有机肥种类(碳氮比)[10-11]、腐熟程度[12]及土壤类型[13]等因素密切相关。有机肥(m(C)/m(N))投入土壤可以有效调控烟株根际土壤碳氮转化过程,并提高土壤酶活性,钾肥分次施用大田烟株生育期内土壤有效钾的供应,以满足烤烟生长发育过程的钾素需求特点,从而降低烟叶刺激性、改善香气质、提高其香气量。钾肥施用提高烤烟叶片的钾含量、改善烟叶品质方面已有大量报道,而有机肥C/N优化下对钾素分期调控及不同基追比例的调节烟叶香气及化学成分方面研究鲜见报道。本研究在前期研究基础上,继续探讨有机肥与氮肥优化条件下华南砂泥田土壤不同钾水平和基追比对烤烟根际土壤钾含量、烟叶钾吸收以及不同部位烟叶香气物质含量的影响,以期改善烤烟钾营养供应,为提高烟叶香气质提供大田钾营养管理依据。

1 材料和方法

1.1 试验材料

试验于2012年在广东省蕉岭县广福镇进行大田试验,供试土壤为砂泥田,排水良好,土壤基本理化性质如下:pH值 6.15,有机质含量为16.8 g/kg、碱解氮含量为130.46 mg/kg、速效磷含量为34.79 mg/kg、速效钾含量为96.63 mg/kg。所用的肥料为硝酸铵(N 含量30%)、钙镁磷肥(P2O5含量 12%)、硫酸钾(K2O含量 50%)、腐熟猪厩肥(N含量 0.50%,P2O5含量 0.20%,K2O含量 0.25%,m(C)/m(N)=94.5)和腐熟花生饼肥(N含量4.60%,P2O5含量 1.00%,K2O含量 1.00%,m(C)/m(N)=10.65)。烤烟品种为云烟87,来自广东省烟草南雄科学研究所。

1.2 试验设计

试验为钾肥及其基追肥比例两因素9个处理,通过裂区试验设计,主处理为施钾量(K2O),设3个水平,K1(120.0 kg/hm2)、K2(240.0 kg/hm2)、K3(360.0 kg/hm2)。副处理为钾肥供应的不同基追比,设3个处理,S1(7∶3)、S2(5∶5)、S3(3∶7),每处理重复3次。无机氮130.5 kg/hm2,采用基肥与团棵期追肥;有机氮施用量为64.5 kg/hm2,采用当地腐熟花生饼肥和猪厩肥(m(C)/m(N) =25),即猪厩肥3 750 kg/hm2、花生饼肥300 kg/hm2,基施;P2O5施用量为 181.5 kg/hm2,即钙镁磷肥1 512.45 kg/hm2,基施。

试验共9个处理,3次重复,18个小区,每个小区面积30.0 m2,采用随机区组排列。选取生长健壮、长势一致的烟苗移栽至每小区,每小区种植1行(行株距为1.2 m×0.6 m)。其他栽培及田间管理措施同常规。

1.3 取样及测定方法

在烤烟移栽后30,45,60,90 d(对应烤烟团棵期、旺长期、现蕾期和成熟期)分次采用抖落法取根际土壤样和烟株样,洗净晾干,将烟叶、茎、根系分开,烘干,测定干质量,在成熟期时按照烟叶收获方法测定。烟叶全钾含量采用H2SO4-H2O2消化-火焰光度计法测定,全氮采用H2SO4-H2O2消化-凯氏定氮法测定,土壤速效钾采用NH4OAc-K法测定,土壤缓效钾采用1 mol/L HNO3浸提,火焰光度法测定[14];烟叶总糖、还原糖、烟碱均采用全自动连续流动法测定[15];烟叶蛋白质含量采用考马斯亮蓝G-250法测定[16];烟叶主要致香物质(6-甲基-5-庚烯-2-酮、β-大马酮、香叶基丙酮、氧化异佛尔酮、二氢猕猴桃内酯、巨豆三烯酮-A、巨豆三烯酮-B、巨豆三烯酮-C、巨豆三烯酮-D、3-羟基-β-二氢大马酮、法尼基丙酮、新植二稀、糠醛、糠醇、2-乙酰呋喃、5-甲基糠醛、3,4-二甲基-2,5-呋喃二酮、2-乙酰基吡咯;苯甲醛、苯甲醇、苯乙醛、苯乙醇)采用气质联用仪(GC/MS)进行分析。

1.4 数据分析

采用SPSS 22.0软件进行单因素显著性检验(SAS Institute Inc., 1989);用最小显著差数法(LSD)进行多重比较(P<0.05);采用Excel 2007制作图表。

2 结果与分析

2.1 钾肥施用量及基追比对烤烟生物量的影响

从图1-A可以看出,与K1水平相比,K2和K3处理烤烟根系生物量显著增加,但是二者之间无显著差异,表明提高施钾量在一定程度上促进了烤烟根系生长;从烤烟茎干质量的变化来看:在团棵期、旺长期时,不同施钾量茎干质量无显著性差异;但是在现蕾期,茎秆生物量随着施钾水平提高而增加;在相同钾水平下和生育期内,3种基追比处理对烤烟茎干质量无显著性影响(图1-B)。从图1-C可以看出,在旺长期、现蕾期和成熟期,烤烟烟叶生物量随着施钾水平的提高而增加,而随着钾追肥比例的增加,烟叶生物量无显著性变化。

不同小写字母表示在同一生育期内不同钾处理结果P<0.05差异显著。图2-3同。
The different lowercase letters after each column of data under the application of potassium level in the same growth stage indicate significant difference under P<0.05.The same as Fig.2-3.

图1 不同水平钾肥及基追比处理对烤烟不同部位生物量的影响
Fig.1 Effect of the different K application and the ratio of basic to dressing on dry weight of flue-cured tobacco

2.2 钾肥施用量及基追比对烤烟整株烟叶及不同部位烟叶钾离子含量的影响

图2表明,随着生育期延长,整株烟叶中钾离子含量呈现逐渐降低的趋势;随施钾量增加烟叶中钾含量显著提高;K1水平下,3个基追比处理对烟叶无显著性影响,在现蕾期与成熟期烟叶钾离子含量随着追肥比例提高而增加:S1处理S2处理>S1处理。

从钾肥施用量及基追比对烤烟现蕾期、成熟期不同部位烟叶钾离子含量的影响来看(表1),3个钾水平下,成熟期时3个部位烟叶钾离子含量均较现蕾期显著降低;K1水平下,现蕾期下、中、上部烟叶钾离子含量无显著性影响,而K2和K3水平下,现蕾期时烟叶钾离子含量顺序为下部叶>中部叶>上部叶,而成熟期时烟叶钾离子含量体现上部叶高于中部叶高于下部叶的趋势。K1水平下,不同基追比水平对不同部位烟叶钾离子含量无显著影响,表明低钾水平时,钾离子从老叶向中上部叶片转移较少,烟叶钾离子含量受到低钾限制;而在K2和K3水平下,S1处理成熟期烟叶钾离子向中上部转移较少,但S2和S3处理成熟期烟叶钾离子从下部叶向中、上部叶转移,满足上部叶对钾离子需求。

图2 基于有机肥C/N优化下钾肥施用量及基追比对烤烟烟叶钾离子含量的影响
Fig.2 Effect of the level and the ratio of basic to dressing of K application on K content in leaves of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer

表1 基于有机肥C/N优化下钾肥施用量及基追比对烤烟现蕾期、成熟期不同部位烟叶钾离子含量的影响
Tab.1 Effect of the level and the ratio of basic to dressing of K application on K content in different leaves of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer mg/kg

生育时期Growth stage period处理Treatment下部叶X2F中部叶C3F上部叶B2F现蕾期K1S122.4±2.2aA21.1±2.2aA22.3±2.2aAFlower budding S222.8±3.1aA21.5±3.1aA22.2±3.1aA(60 d)S324.2±2.0aA22.3±2.0aA22.9±2.0aAK2S127.2±1.7aB24.8±1.7aB23.3±1.7aAS227.1±1.8aB25.9±1.8abB24.8±1.8abAS331.0±2.9bB27.4±2.9bB26.0±2.9bBK3S131.5±1.4aC30.0±1.4aC28.6±1.4aCS232.4±1.5abC30.1±1.5abC29.7±1.5abCS335.3±2.6bC32.8±2.6bC31.3±1.6bC成熟期K1S117.4±2.0aA17.5±1.3aA18.8±1.7aAMature periodS218.0±0.6aA18.8±0.8aA18.9±0.8aA(90 d)S318.3±1.2aA17.9±0.5aA20.9±0.9aAK2S119.1±1.8aA22.7±1.0aB21.0±1.0aBS220.9±1.4aB23.6±2.1aB24.0±1.1bBS325.2±2.0bB23.9±1.2aB24.9±0.8bBK3S122.1±1.6aA23.2±1.1aB25.3±1.3aCS225.3±1.2bB25.9±1.4bC28.5±1.5bCS327.4±1.8cB28.7±0.5cC29.0±1.9bC

注:同一生育期内相同钾水平下不同基追比处理数据后(每列)不同小写字母表示在P<0.05差异显著;同一生育期内相同基追比处理下不同钾水平处理数据后(每列)不同大写字母表示在P<0.05差异显著。

Note: The different lowercase letters after each column of data of the ratio of different basic to dressing under the application of potassium level in the same growth stage indicate significant difference under P<0.05; The different capital letters after each column of data of different potassium level under the application of potassium level in the same ratio of basic to dressing in the same growth stage indicate significant difference under P<0.05.

2.3 钾肥施用量及基追比对土壤供钾能力的影响

根际土壤速效钾含量随施钾水平提高而增加(图3-A);K1水平下,现蕾期和成熟期根际土壤速效钾含量S3处理低于S1和S2处理,表明低钾水平供应导致土壤后期供钾不足(图3-A)。K2条件下,旺长期和现蕾期根际土壤速效钾含量,高于团棵期和成熟期;从相同基追比处理来看,在成熟期时,K3处理根际土壤速效钾含量高于K1和K2处理;K3水平条件下,根际土壤速效钾在4个生育期内变化不显著,且不同基追比处理间差异也不显著,S3处理>S1处理>S2处理。从根际土壤缓效钾含量来看(图3-B),K3处理烤烟现蕾期、成熟期根际土壤缓效钾含量显著高于K1和K2处理,而后两者之间无显著性差异;而团棵期和旺长期根际土壤缓效钾含量在3个供钾水平和3个基追比处理之间无显著性差异。

图3 基于有机肥C/N优化下钾肥施用量及基追比对烤烟根际土壤速效钾(A)和缓效钾(B)含量的影响
Fig.3 Effect of the level and the ratio of basic to dressing of K application on the available K(A) and slowly available K(B)in rhizosphere soil of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer

2.4 钾肥施用量及基追比对烤后烟叶主要品质指标的影响

由表2可以看出,不同处理烤烟的烟叶主要品质指标变化分别为:总氮(16.0~20.8 mg/g),总烟碱(20.1~25.4 mg/g),蛋白质(61.5~90.4 mg/g),还原糖(220.0~264.0 mg/g),总糖(221.4~289.0 mg/g),氮/碱(0.63~0.92),还原糖/碱(8.67~11.39)和还原糖/总糖(0.86~1.04)。表明有机肥碳氮比优化条件下,不同钾用量及其基追比影响烤烟叶片的总氮、总烟碱和蛋白质的含量,钾水平的提高和钾肥后移可改善烟叶还原糖/碱和氮/碱(表2)。所以,调控钾肥用量和基追比可有效改善烟叶的品质和燃烧性。

2.5 钾肥施用量及基追比对烤后烟叶中性香气成分含量的影响

对上等品级的中部烟叶(C3F)和上部烟叶(B2F)检测发现,总共检测出28 种中性致香成分,其中包括15 种胡萝卜素类、5 种棕色化产物类、5 种苯丙氨酸类、3 种类西柏烷类(表3,4)。3个钾肥施用量下,烟叶中性致香物质的种类基本一致,但是K1处理烟叶中性致香物质总含量(除新植二烯外)低于K2和K3处理,且中部烟叶(C3F)高于上部烟叶(B2F)(表3,4)。与K1水平相比,K2和K3处理烟叶中性致香物质总量有不同程度提高;并随着追肥比例提高而增加;但是K1水平条件下,烟叶中性致香物质在不同基追比S1、S2和S3处理之间无显著性差异。由此可见,中高钾水平处理下,提高后期施钾比例(基追比调控)明显提高烟叶中性致香物质含量,特别是对于上部烟叶。

2.6 钾肥施用量及基追比对烤后烟叶感官质量的影响

有机肥碳氮优化条件下,调控钾肥基追比例对烟叶感官质量有较大影响(表5)。从总分来看,随钾肥供应水平的提高,烟叶感官质量总得分提高;同等钾肥水平下,随钾肥基追比减小(后期供钾量增加),明显改善烟叶香气质、提高香气量、浓度和劲头,而对杂气、刺激性、余味等无显著性影响;在K2和K3水平下,与S1相比,S2和S3处理烟叶烟气香气质、香气量和浓度显著提高,烟气劲头适中。总体而言,钾肥基追比调控对上部烟叶的感官质量影响较大,增加后期钾肥供应比例明显提高了上部烟叶香气质,提高香气量、浓度和劲头。

表2 基于有机肥C/N优化下钾肥施用量及基追比对烤后烟叶(C3F和B2F)主要品质指标含量的影响
Tab.2 Effect of the level and the ratio of basic to dressing of K application on the content of chemical compounds of roasted tobacco leaves (C3F and B2F) of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer

烟叶部位Tobaccoposition处理Treatment总氮/(mg/g)Totalnitrogen总烟碱/(mg/g)Totalnicotine蛋白质/(mg/g)Protein还原糖/(mg/g)Reducingsugar总糖/(mg/g)Totalsugar氮/碱Nitrogen/Alkali还原糖/碱Reducingsugar/Alkali还原糖/总糖Reducing sugar/Total sugarC3FK1S118.4±0.6aA20.1±0.5aA63.2±1.6bA229.0±6.8aA244.0±3.8bA0.92c11.39a0.94aS217.9±0.8aA22.3±0.7bA67.4±1.4cA236.0±7.3aA229.0±6.5aA0.80b10.58a1.03aS318.2±0.7aA25.2±0.8cC61.5±1.6aA263.0±5.2bA254.0±8.3cB0.72a10.44a1.04aK2S118.8±0.2aB24.1±0.3aB65.7±2.3aB230.0±6.3aA269.0±4.8aC0.78a9.54a0.86aS219.1±0.3bB24.6±0.8aB69.9±2.6bA247.0±3.5aB284.0±5.9bC0.78a10.04b0.87aS318.4±0.5aB23.9±0.6aB79.9±1.7cB264.0±4.7bA289.0±3.8bC0.77a11.05c0.91aK3S118.6±0.3bA24.1±0.4cB82.0±2.8cC231.0±4.8aA254.0±5.4bB0.77b9.59a0.91aS218.5±0.7bAB23.2±0.7bB77.8±1.4bB244.0±6.3aB252.0±6.8bB0.80b10.52b0.97aS316.7±0.8aA22.9±0.8aA61.9±3.7aA237.0±5.3aA244.2±7.6aA0.73a10.35b0.97aB2FK1S119.2±0.3aA25.4±0.4aC65.0±2.2aA220.3±5.8aA239.0±5.4b0.76b8.67a0.92abS218.5±0.6aA25.4±0.7aC68.8±3.5bA220.6±4.4aA221.4±7.6a0.73b8.69a1.00bS316.0±0.4aA25.4±0.5aC65.4±1.5aA220.9±3.4aA249.0±4.8b0.63a8.70a0.89aK2S118.4±0.6aA23.2±0.3aB66.2±2.3aA231.2±5.3aB254.0±5.8b0.79a9.97a0.91aS220.8±0.8bB23.5±0.5aB70.0±3.7bA231.5±4.2aB249.0±3.7a0.89a9.85a0.93aS318.6±0.4aA23.1±0.6aB64.4±1.8aA238.0±5.4aB244.0±7.8a0.81a10.30a0.98bK3S119.1±0.4aB22.5±0.7aA90.4±2.8cB224.0±8.4aA239.0±5.3b0.85a9.96a0.94aS220.1±0.3bB22.3±0.3aA83.3±2.8bB220.0±5.2aA223.0±3.8a0.90a9.87a0.99aS319.7±0.3aB22.7±0.5aA79.2±1.8aB217.0±4.8aA224.0±2.5a0.87a9.56a0.97a

注:同一部位相同钾水平下不同基追比处理数据后(每列)不同小写字母表示在P<0.05差异显著;同一部位相同基追比处理下不同钾水平处理数据后(每列)不同大写字母表示在P<0.05差异显著。

Note: The different lowercase letters after each column of data of the ratio of different basic to dressing under the application of potassium level in sameleaf indicate significant difference under P<0.05; The different capital letters after each column of data of different potassium level under the application of potassium level in the same ratio of basic to dressing in the same in same leaf indicate significant difference under P<0.05.

表3 基于有机肥C/N优化下钾肥施用量及基追比烤后中部烟叶(C3F)中性香气成分含量
Tab.3 Effect of the level and the ratio of basic to dressing of K application on the content of neutral aroma components of roasted middle leaves (C3F) of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer μg/g

香气物质Aroma componentsK1K2K3S1S2S3S1S2S3S1S2S3糠醛 Furfuraldehyde14.8014.6014.2014.9015.7015.7021.2021.5019.70糠醇 Furfuralcohol2.632.902.172.642.712.723.313.793.852-乙酰呋喃 2-furyl methyl ketone1.121.101.161.651.631.652.541.921.755-甲基糠醛 5-methyl furfural2.392.702.152.602.352.502.772.952.83苯甲醛 Benzaldehyde2.662.302.943.363.252.993.785.114.216-甲基-5-庚烯-2-酮 6-methyl-5-hepten-2-one1.781.821.721.871.771.792.172.432.98苯甲醇 Phenylcarbinol5.174.994.995.475.385.696.536.317.623,4-二甲基-2,5-呋喃二酮 3,4-dimethyl-2,5-furan diketone0.800.710.740.850.840.810.940.890.97苯乙醛 Benzene acetaldehyde4.234.764.884.055.514.584.624.874.112-乙酰基吡咯 2-acetyl pyrrole1.891.781.771.741.621.781.841.911.86芳樟醇 Linalool2.742.662.793.133.132.983.183.243.47苯乙醇 Benzene ethanol3.293.143.163.283.283.323.523.533.98氧化异佛尔酮 Oxidation of isophorone0.310.300.330.320.310.330.390.390.42吲哚 Indole1.701.641.481.321.381.391.421.521.574-乙烯基-2甲氧基苯酚 4-vinyl-2methoxy phenol5.867.337.043.556.565.483.293.995.36茄酮 Solanone97.3097.3094.4095.40104.60112.00113.90121.30125.60β-大马酮 β-damascenone33.431.3034.0035.2035.5035.4035.6035.9035.10香叶基丙酮 Geranyl acetone2.382.462.183.133.233.435.285.637.36

表3(续)

香气物质Aroma componentsK1K2K3S1S2S3S1S2S3S1S2S3脱氢-β-紫罗兰酮 Dehydrogenation-β-ionone0.120.110.130.140.130.130.130.130.13二氢猕猴桃内酯 Dihydroactinidiolide3.463.613.563.533.593.613.343.393.38巨豆三烯酮1 Megastigmatrienone-12.382.531.932.562.642.472.452.842.73巨豆三烯酮2 Megastigmatrienone-210.6010.6010.4011.1011.5010.6012.1011.5012.90巨豆三烯酮3 Megastigmatrienone-32.252.342.382.762.672.313.112.942.88三羟基-β-二氢大马酮 Three ketone of hydroxy-β-dihydromalaysia1.481.421.561.351.781.452.151.861.60巨豆三烯酮4 Megastigmatrienone-410.2012.3010.1013.2013.0012.9012.7012.1012.70螺岩兰草酮 Screw vetiver ketone0.160.180.190.230.230.230.230.240.25法尼基丙酮 Nicky acetone12.3512.6512.2915.1916.7818.2917.3217.1616.98新植二烯 Neophytadiene1 468.001 462.001 499.001 421.001 399.001 198.001 511.001 411.001 326.00合计(除新植二烯外) Total (Except neophytadiene)227.50229.60224.60234.50250.90256.50269.70279.30286.20

表4 基于有机肥C/N优化下钾肥施用量及基追比烤后上部烟叶(B2F)中性香气成分含量的影响
Tab.4 Effect of the level and the ratio of basic to dressing of K application on the content of neutral aroma components of roasted upper leaves (B2F) of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer μg/g

香气物质Aroma componentsK1K2K3S1S2S3S1S2S3S1S2S3糠醛Furfuraldehyde21.1121.6822.2522.8923.2923.7623.1323.1023.67糠醇 Furfuralcohol2.982.982.972.842.952.974.544.794.892-乙酰呋喃 2-furyl methyl ketone1.121.101.161.651.631.652.541.921.755-甲基糠醛 5-methyl furfural2.522.572.552.682.652.652.792.992.98苯甲醛 Phenylcarbinol2.762.833.113.373.293.213.783.013.216-甲基-5-庚烯-2-酮 6-methyl-5-hepten-2-one1.992.081.981.971.911.942.212.483.03苯甲醇 Phenylcarbinol5.174.994.995.475.385.696.536.317.623,4-二甲基-2,5-呋喃二酮 3,4- dimethyl-2,5-furan diketone0.800.710.740.850.840.810.940.890.97苯乙醛 Benzene acetaldehyde4.115.424.234.154.214.184.223.674.322-乙酰基吡咯 2-acetyl pyrrole1.761.771.821.841.921.791.881.871.78芳樟醇 Linalool2.752.642.873.113.113.053.123.123.22苯乙醇 Benzene ethanol3.232.843.123.113.123.213.223.233.18氧化异佛尔酮 Oxidation of isophorone0.350.330.370.390.300.340.360.310.31吲哚 Indole1.671.671.591.471.491.421.471.531.594-乙烯基-2甲氧基苯酚 4-vinyl-2methoxy phenol3.753.783.653.843.743.913.933.983.87茄酮 Solanone78.4678.3478.6783.2584.4591.2495.5697.6598.65β-大马酮 β-damascenone23.4324.5624.7325.4526.4326.7826.3426.8926.58香叶基丙酮 Geranyl acetone2.432.492.433.113.123.134.164.275.39脱氢-β-紫罗兰酮 Dehydrogenation-β-ionone0.120.110.130.140.130.130.130.130.13二氢猕猴桃内酯 Dihydroactinidiolide2.122.112.262.422.672.683.113.213.23巨豆三烯酮1 Megastigmatrienone-12.432.442.332.642.562.582.572.742.79巨豆三烯酮2 Megastigmatrienone-212.1412.6712.7612.6412.6812.4212.8212.7812.79巨豆三烯酮3 Megastigmatrienone-32.612.662.692.762.792.882.992.963.11三羟基- β-二氢大马酮Three ketone of hydroxy-β-dihydro1.511.551.571.561.691.702.551.991.86巨豆三烯酮4 Megastigmatrienone-49.369.9910.0111.5412.3612.7612.9812.9912.76螺岩兰草酮 Screw vetiver ketone0.190.170.210.220.210.220.210.210.21法尼基丙酮 Nicky acetone13.9513.9513.9515.5616.6717.5717.8917.9917.34新植二烯 Neophytadiene1 672.001 369.001 087.001 266.001 381.001 163.001 501.001 422.001 393.00合计(除新植二烯外) Total ( Except neophytadiene)204.80208.40209.10220.90225.60234.70246.00247.00251.20

表5 基于有机肥C/N优化下钾肥施用量及基追比烤后烟叶感官质量的影响
Tab.5 Effect of the level and the ratio of basic to dressing of K application on the smoking quality of roasted leaves of flue-cured tobacco under the optimization of C/N with organic fertilizer and N fertilizer

处理Treatment香气质Aroma quality香气量Amount of aroma浓度Concentration劲头Strength杂气Offensive odor刺激性Irritation余味Aftertaste总分TotalK1S16.0 6.0 6.0 6.0 6.5 6.5 6.5 43.5 S26.5 6.0 6.0 6.0 6.5 6.5 6.5 44.0 S36.5 6.5 6.5 6.0 6.5 6.5 6.5 45.0 K2S17.0 6.0 6.0 6.0 6.0 6.5 6.5 44.0 S27.0 6.5 6.5 6.0 6.5 6.5 6.5 45.5 S37.5 6.5 6.5 6.0 6.5 6.5 6.5 46.0 K3S16.5 7.0 7.0 6.0 6.5 6.5 6.5 46.0 S27.5 7.5 7.0 7.0 6.5 6.5 6.5 48.5 S37.5 7.5 7.0 7.0 6.5 6.5 6.5 48.5 赋值标准Value-determined standard分值Value香气质Aroma quality香气量Amount of aroma浓度Concentration劲头Strength杂气Offensive odor刺激性Irritation余味Aftertaste7.6~9.0好、较好足、充足很浓、浓很大、大无、似有无、似有舒适6.1~7.5中偏上尚充足较浓较大较轻微有较舒适4.6~6.0中等有中等中等有有尚舒适3.1~4.5中偏下较少较淡较小略重略大欠舒适

3 结论与讨论

3.1 有机肥C/N优化下钾肥用量和基追比对砂泥田烤烟生长、钾素吸收及土壤速效钾含量的影响

钾肥是烤烟施肥量最大的一种肥料,钾素能够促进烤烟生长发育,具有增产增质效果,对改善烤烟内在品质具有重要的现实意义,其作用不能用其他无机离子替代[17]。但盲目增施钾肥必然会大幅度增加烤烟肥料成本投入,进而降低烤烟生产的效益。所以,如何根据烤烟的吸钾规律,做到充分有效、适时适量地满足烟株对钾素营养的需求,是烤烟钾肥合理施用的关键。据曹志洪等[18]研究报道:南方烤烟对钾的吸收前期较少,吸钾高峰期在移栽后的9~11周,大多数烟农都是将330~370 kg/hm2的钾(K2O)相对集中在烟苗移栽后的40 d内施完。这种在较短时期内的集中施用在土壤中极易淋失,土壤对钾的固定也较严重,致使烤烟生育后期的需钾高峰期土壤钾素供应不足,土壤供钾与烤烟生长钾素需求不匹配,进而影响烟叶的产量和品质[19]。本研究表明,随施钾量提高,根际土壤速效钾和缓效钾含量增加,中钾处理旺长期、现蕾期根际土壤速效钾含量最高;成熟期时基追比3∶7处理根际土壤速效钾含量低于基追比7∶3、5∶5处理;高钾水平时,根际土壤速效钾在4个生育期内无显著差异,但基追比3∶7>7∶3>5∶5。

钾在烟株体内以K+形式存在,作为移动性很强的阳离子,钾在烟株体内具有重要的生理作用,钾可以作为渗透调节物质维持植株细胞渗透势,其积累过程影响细胞对渗透胁迫的适应[20]。Watad等[21]研究发现,细胞内K 的代谢是植物适应盐渍和干旱环境及渗透调节的重要环节。施用钾肥促进了烟株的根系活力且影响效应随着供钾强度增加而增加。K 在叶绿体的合成与稳定方面具有重要作用,在烟株生长前期,钾肥施用能够提高叶片叶绿素含量,而在烟株生长后期,叶绿素含量的适时降低促进叶片的成熟落黄[20]。本研究结果表明:旺长期-成熟期时,烟叶生物量随施钾量增加而提高,而随钾追肥比例增加,烟叶生物量降低;中、高钾时,基追比7∶3时成熟期烟叶钾离子转移低,但基追比5∶5和3∶7时成熟期烟叶钾供应充足,钾离子由下部叶向中、上部叶转移。

3.2 有机肥C/N优化下钾肥用量和基追比对砂泥田土壤烟叶化学成分及致香成分改善的影响

烟叶化学成分与感官评吸质量密切相关,烟叶糖/烟碱的比例是形成均衡烟气的重要因素[22]。若糖含量过高,烟碱含量过低,烟气香味平淡、缺乏劲头;反之,烟气劲头强烈,刺激性增大。一般认为优质烟中总糖含量为18%~22%,还原糖为16%~20%,总氮为1.5%~3.5%,氮碱比为0.8~0.9,糖碱比则为10,烟碱含量在1.5%~3.5%为宜。李祖莹等[23]研究表明,使烤烟叶片的总氮、总烟碱和蛋白质含量趋于合理,促进糖碱比、氮碱比更加协调,从而改善烟叶品质。合理投入有机肥可提高烤烟生长后期的饱和脂肪酸、类胡萝卜素、乙醚提取物含量,降低不饱和脂肪酸的含量,并能促进烟叶对钾素的吸收,改善烟叶的燃烧性。而本研究表明,与其他处理相比,中钾用量及追肥比例增加可优化烟叶总氮、总烟碱和蛋白质含量,改善糖碱比,氮碱比趋于合理,表明钾肥供应量在240.0 kg/hm2及基追比3∶7可提高后期烟叶钾含量,改善烟叶燃烧性。

烟叶香气不足是目前影响烟叶质量尤其是香气质量的重要品质因素之一。因此,提高烟叶的香气质量是当前烟叶优化生产中急待解决的问题。烟叶香气是评价烤烟质量的核心内容和重要指标,而烟叶致香物质含量高低与其香气质量密切相关,而烟叶香气质量是由多种香气成分的组成、含量、比例及相互作用所决定的[24]。傅献忠等[25]研究表明,有机肥的投入可以明显改善烟气醇正度,使烟叶香气幽雅丰富、甜润明显。胡保文等[26]试验表明,施用有机肥提高了烟叶的香气和柔细度,改善了吃味和吸味,减少了杂气,其中又以施30%有机肥的处理最好。施用钾肥能够显著改善烟叶的内在外观品质。尽管影响烤烟香气的因素很多,但是在品种和栽培措施相对稳定条件下,通过钾肥供应调节来提高烟叶的香气含量,是当前烤烟生产中的可行性技术途径[27]

本研究表明,低钾处理时,上部叶在不同基追比间无显著差异;中、高钾处理时,通过增加后期钾供应(基追比3∶7)提高烟叶(特别上部烟叶)中性致香物质含量。钾肥基追比降低(后期供钾增加)明显改善中、下部烟叶香气质,提高香气量、浓度和劲头,而对杂气、刺激性、余味等无显著影响;随后期钾肥供应增加,烟叶感官质量提高,但钾肥供应过高(360.0 kg/hm2)对烟叶香气质、香气量、浓度和劲头无显著影响;而中量(240.0 kg/hm2)钾肥下,基追比3∶7(后期供钾增加)明显提高烟叶香气质、香气量、浓度,劲头适中,而对杂气和刺激性影响不大。由此可见,中钾处理下,提高后期钾肥供应(基追比调控)对提高烟叶中性致香物质含量效果较佳,特别是上部烟叶。

综上所述,基于有机肥C/N优化条件下,调节钾肥用量和基追比对烤烟生物量、钾素吸收、土壤速效钾含量及香气品质改善效果显著。旺长期-成熟期时,烟叶生物量随施钾量增加而提高,而随钾追肥比例增加,烟叶生物量降低;中、高钾水平下钾肥后移成熟期烟叶钾供应充足,钾离子由下部叶向中、上部叶转移。随施钾量提高,根际土壤速效钾和缓效钾含量增加,中钾处理旺长期、现蕾期根际土壤速效钾含量最高。对烟叶品质而言,中、高钾处理时,通过增加后期钾供应(基追比3∶7)提高烟叶(特别上部烟叶)中性致香物质含量。钾肥后移明显改善中、下部烟叶香气质、提高香气量、浓度和劲头,而对杂气、刺激性、余味等无显著影响;随后期钾肥供应增加,烟叶感官质量提高,但钾肥供应过高(360.0 kg/hm2)对烟叶香气质、香气量、浓度和劲头无显著影响。所以,有机肥C/N优化后,华南砂泥田土壤钾肥供应量在240.0 kg/hm2,基肥(移栽前条施后覆膜)72.0 kg/hm2与追肥以168.0 kg/hm2施用(基追比为3∶7)。

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Effect of K Application Level on Biomass, K Absorption and Quality of Flue-cured Tobacco in Sand Mud Soil

ZHANG Shirong1, WANG Jun2, LIN Changhua3, DING Xiaodong1

(1.College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109,China;2.Nanxiong Tobacco Science Institute of Guangdong, Guangdong Tobacco Technology Center, Nanxiong 512400,China;3.Henry Fok School of Agricultural Science and Engineering, Shaoguan University,Shaoguan 512005,China)

Abstract Under the optimization of C/N with organic fertilizer and N fertilizer, a field experiment was carried out to study the effect of potassium and the ratio of basic/dressing fertilizer on biomass, potassium uptake, soil available potassium content and aroma quality of tobacco. Split-plot experiment design was adopted. The main treatment was 3 K level: K1 (120.0 kg/ha),K2 (240.0 kg/ha) and K3 (360.0 kg/ha);and the subsidiary treatment was the ratio of basic/dressing K fertilizer:S1(7∶3),S2(5∶5) and S3(3∶7). The results showed that the biomass of tobacco leaves increased with the increase of potassium application, while it decreased with the increase of potassium dressing ratio in the same K level in the fast growth and mature period. Under the K2 and K3 level, the leaf potassium content was lower in the S1 treatment than in S2 and S3 treatments, indicating that the increase of K dressing percentage was conducive to the transfer of potassium ions from lower leaves to middle and upper leaves. With the increase of potassium application, the content of available and slowly available potassium in rhizosphere soil increased. Under K2 level, the available potassium of soil reached to maximum at fast growth and bud stages, and was lower in S3 treatment than in S1 and S2 treatments at mature stage. Under K3 level, the available potassium in rhizosphere soil had no significant difference among the four growth stages, in which that of S3 treatment>S1 treatment>S2 treatment. Compared with other treatments, the contents of total nitrogen, total nicotine and protein in tobacco leaves were significantly higher in S3 treatment under K2 level, and the ratio of sugar/alkali and ratio of nitrogen/alkali were improved. The neutral aroma components had no significant difference in upper leaves under K1 level, but it improved significantly in S3 treatment under K2 and K3 levels, especially for S3 treatment under the K2 level, in which the quality, quantity and concentration of aroma in tobacco leaves were the best. It was concluded that under the optimization conditions of organic fertilizer C/N, 240.0 kg/ha potassium fertilizer was recommended in the sand mud soil of Southern China, and the basic fertilizer was 72.0 kg/ha and the dressing one was 168.0 kg/ha (the ratio of base to dressing was 3∶7), which could effectively improve the potassium content and quality of tobacco leaves.

Key words: Flue-cured tobacco; Potassium fertilizer; Sand mud field soil;The ratio of base to dressing; Potassium supply capacity; Quality index; Neutral aroma components

中图分类号:S143.3

文献标识码:A

文章编号:1000-7091(2019)02-0187-11

doi:10.7668/hbnxb.201751060

收稿日期:2018-11-06

基金项目:广东省烟草专卖局(公司)科技项目(201303;201306);韶关市2015年科技计划项目(韶科[2015]72号);山东省烟草创新团队(栽培与土肥岗位, SDAIT-25-04)

作者简介:张士荣(1980-),女,山东临沂人, 副教授, 博士,主要从事土壤与植物营养研究。

通讯作者:丁效东(1978-),男, 山东寿光人, 教授, 博士, 主要从事土壤与植物营养研究。