为明确化肥减量和添加生物炭对植烟土壤氮素淋失的影响,采用室内土柱试验,研究了不同施肥处理(常规施肥,化肥减量30％,化肥减量30％+5％生物炭,不施肥)下,褐土、红壤、紫色土中有效氮淋失量变化.结果表明,淋洗前期各形态氮的淋失量较大,随时间推移逐渐减弱.淋失的氮主要为可溶性总氮及硝态氮.与常规施肥相比,化肥减量处理的可溶性总氮、硝态氮、铵态氮淋失量分别减少12.0％～21.8％、8.9％～22.5％、12.7％～25％;化肥减量+生物炭的处理能够明显延缓土壤中氮素淋失出现的时间,可溶性总氮、硝态氮淋失量分别减少26.6％～35.4％、36.5％～59.2％.总之,化肥减量或添加生物炭能减少土壤中可溶性总氮及硝态氮的淋失量.

为探究油菜素内酯(BRs)对烟草幼苗根系构型的调控机制,选取烤烟品种农大202为试验材料,分析不同浓度外源EBR(2,4-表油菜素内酯)和BRZ(BRs合成抑制剂)处理下烟草幼苗根系构型的差异,通过电镜观察二级侧根根尖横截面变化,并观察烟草转基因DR5::GUS材料根系GUS(β-葡萄糖苷酸酶)染色情况,测定侧根中生长素含量和相关基因表达量,分析根系构型变化与生长素之间的关系.结果表明,EBR可以调节烟草幼苗根长、根系直径与二级侧根密度变化,较低浓度的EBR(0.1 nmol/L)使总根长增加,增幅达到29.0％,但在0.5、1、5、10、100 nmol/L EBR处理下,一级侧根长度与对照(不添加EBR 和 BRZ)相比分别降低 4.6％、9.6％、18.5％、29.6％、36.9％;随着 EBR 浓度的增大(0.1～10 nmol/L),二级侧根密度不断增大,但根系平均直径逐渐减小,BRZ(100～500 nmol/L)处理后烟草根系平均直径显著增大;EBR主要通过调控烟草侧根细胞数目和中柱直径影响烟草幼苗根系直径大小,10 nmol/L EBR处理下烟草二级侧根横切直径较CK显著减少32.5％,中柱直径较CK显著减小25.0％;10 nmol/L EBR处理下,烟草侧根生长素含量较CK显著降低7.1％,500 nmol/LBRZ处理下,侧根生长素含量与CK相比无变化;EBR处理使烟草生长素运输基因家族中PIN3aT、PIN3bS、PIN3bT和PIN11T等基因上调,从而调控根中生长素的分布.可见,油菜素内酯可以调控根中不同部位生长素的水平进而影响烟草根系构型的变化.

Annual removal of tobacco residues and insufficient input of organic materials have exacerbated total organic carbon (TOC) depletion and soil degradation in a tobacco field in the Huanghuai area. Straw residue and biochar application may be effective ways to increase TOC accumulation and improve soil fertility. In this field experiment, wheat straw (WS) and wheat-straw-derived biochar (BC) with mineral fertilizer were compared with mineral fertilizer alone (CK), and we assessed their effects on soil organic carbon fractions, enzyme activities, and nutrients in Shandong Province, China, during 2016 and 2017. At 0–20 cm depth, the WS treatment had a greater overall effect on the measured soil properties. Compared with the control, the WS treatment significantly increased the concentrations of microbial biomass carbon (MBC), hot-water-extractable carbon (HWC), and permanganate-oxidizable carbon concentrations (POXC; by 252.41%, 107.02%, and 65.53%, respectively); the activities of sucrase, urease, and phosphatase (by 112.52%, 7.81%, and 34.33%, respectively); and the contents of alkaline hydrolysable nitrogen, available phosphorus, and available potassium (by 92.22%, 100.78%, and 10.57%, respectively). Compared with the control, the BC treatment significantly increased TOC content, MBC content, light fraction organic carbon (LFOC), and potassium (TK) concentration (by 74.93%, 86.24%, 153.73%, and 21.92%, respectively). Most soil enzyme activity and nutrient parameters were significantly correlated with MBC. Thus, straw application improved soil fertility by increasing the concentrations of high labile organic carbon fractions (HWC, MBC, and POXC), stimulating soil enzyme activities, and releasing more soil available nutrients, and BC addition contributed to the accumulation of TOC, MBC, LFOC, and TK.

Drought stress hinders the growth and development of crop plants and ultimately its productivity. It is expected that drought stress will be frequent and intense in the future due to drastic changes in the global climate. It is necessary to make crop plants more resilient to drought stress through various techniques; drought-hardening is one of them. Defining various metabolic strategies used by tobacco plants to confer drought tolerance will be important for maintaining plant physiological functions, but studies addressing this topic are limited. This study was designed to elucidate the drought tolerance and adaptation strategies used by tobacco plants via the application of different circular drought-hardening cycles (control: no drought-hardening, T1: one cycle of drought hardening, T2: two cycles of drought-hardening, and T3: three cycles of drought-hardening) to two tobacco varieties namely Honghuadajinyuan (H) and Yun Yan-100 (Y). The results revealed that drought-hardening decreased the fresh and dry biomass of the tobacco plants. The decrease was more pronounced in the T3 treatment for both H (23 and 29%, respectively) and Y (26 and 31%, respectively) under drought stress. The MDA contents, especially in T1 and T2 in both varieties, were statistically similar compared with control under drought stress. Similarly, higher POD, APX, and GR activities were observed, especially in T3, and elevated amounts of AsA and GSH were also observed among the different circular drought-hardening treatments under drought stress. Thus circular drought-hardening mitigated the oxidative damage by increasing the antioxidant enzyme activities and elevated the content of antioxidant substances, a key metabolic strategy under drought stress. Similarly, another important plant metabolic strategy is the osmotic adjustment. Different circular drought-hardening treatments improved the accumulation of proline and soluble sugars contents which contributed to osmoregulation. Finally, at the molecular level, circular drought-hardening improved the transcript levels of antioxidant enzyme-related genes (CAT, APX1, and GR2), proline and polyamines biosynthesis-related genes (P5CS1 and ADC2), and ABA signaling (SnRK2), and transcription factors (AREB1 and WRKY6) in response to drought stress. As a result, circular drought-hardening (T2 and T3 treatments) promoted tolerance to water stress via affecting the anti-oxidative capacity, osmotic adjustment, and regulation of gene expression in tobacco.

Low temperature is among the most significant abiotic stresses restricting geographical distribution of plants and reducing crop productivity. However, the molecular regulatory mechanisms of tobacco plants in response to low temperature are poorly understood. To elucidate the molecular mechanisms of chilling tolerance in tobacco, the transcriptomic responses of tobacco under chilling stress were analyzed using RNA-seq analysis. A total of 1675 differentially expressed genes (DEGs) were detected from T12h vs. CK12h and T24h vs. CK24h libraries; among these genes, 1170 genes were upregulated and 505 were downregulated. Additionally, 109 genes were found to be specifically expressed in tobacco seedlings under chilling stress. Functional annotation revealed that the DEGs enriched that categories of regulating soluble sugar and polyamine content and composition to maintain cell osmotic potential, accelerating the de novo synthesis of D1 protein to promote PSII repair, regulating signal transduction such as ABA and GA, and promoting lipid metabolism and lignin synthesis to improve stability of membrane system and mechanical strength of cell wall. This work provides additional insights into the molecular basis of tobacco seedling responses to low-temperature stress.

Background Drought stress is the most harmful one among other abiotic stresses with negative impacts on crop growth and development. Drought-hardening is a feasible and widely used method in tobacco seedlings cultivation. It has gained extensive interests due to its role in improving drought tolerance. This research aimed to investigate the role of drought-hardening and to unravel the multiple mechanisms underlying tobacco drought tolerance and adaptation. Results This study was designed in which various drought-hardening treatments (CK (no drought-hardening), T1 (drought-hardening for 24 h), T2 (drought-hardening for 48 h), and T3 (drought-hardening for 72 h)) were applied to two tobacco varieties namely HongHuaDaJinYuan (H) and Yun Yan-100 (Y). The findings presented a complete framework of drought-hardening effect at physiological, biochemical, and gene expression levels of the two tobacco varieties under drought stress. The results showed that T2 and T3 significantly reduced the growth of the two varieties under drought stress. Similarly, among the various drought-hardening treatments, T3 improved both the enzymatic (POD, CAT, APX) and non-enzymatic (AsA) defense systems along with the elevated levels of proline and soluble sugar to mitigate the negative effects of oxidative damage and bringing osmoregulation in tobacco plants. Finally, the various drought-hardening treatments (T1, T2, and T3) showed differential regulation of genes expressed in the two varieties, while, particularly T3 drought-hardening treatment-induced drought tolerance via the expression of various stress-responsive genes by triggering the biosynthesis pathways of proline ( P5CS1 ), polyamines ( ADC2 ), ABA-dependent ( SnRK2 , AREB1 ), and independent pathways ( DREB2B ), and antioxidant defense-related genes ( CAT , APX1 , GR2 ) in response to drought stress. Conclusions Drought-hardening made significant contributions to drought tolerance and adaptation in two tobacco variety seedlings by reducing its growth and, on the other hand, by activating various defense mechanisms at biochemical and molecular levels. The findings of the study pointed out that drought-hardening is a fruitful strategy for conferring drought tolerance and adaptations in tobacco. It will be served as a useful method in the future to understand the drought tolerance and adaptation mechanisms of other plant species. Graphical abstract Drought-hardening improved drought tolerance and adaptation of the two tobacco varieties. T1 indicates drought-hardening for 24 h, T2 indicates drought-hardening for 48 h, T3 indicates drought-hardening for 72 h

为探讨翻压绿肥对黑龙江烟草田间生长状态的影响,研究4种绿肥翻压后对烟草农艺性状、光合作用、根系生长发育、叶片SPAD值的影响.结果表明,翻压绿肥草木樨和紫花苜蓿可以促进烟叶生长;翻压紫花苜蓿、小麦和草木樨可显著促进烟叶田间光合作用;翻压绿肥紫花苜蓿、草木樨和小麦处理对增加烟株根系长度、直径、体积和侧根数有显著影响;翻压绿肥对烟草中下部叶片SPAD值有显著影响,对上部叶片无明显影响;紫花苜蓿、小麦和草木樨处理可显著降低叶片中叶绿素含量,促进烟叶成熟落黄,改善烟株田间成熟度.总的来看,在黑龙江烟区进行翻压草木樨和小麦可以改善烟草田间生长状态.

为探讨翻压绿肥对黑龙江烤烟品质改善及经济价值提升的作用,研究套种4种绿肥并翻压后对烤烟产质量的影响.在烤烟采收后将绿肥就地翻压腐解,并于第2年测定种植烤烟后烤烟理化指标及内在和外在质量品质的改善情况.结果 表明:7月末套种绿肥对烤烟当年主要经济性状和化学成分影响较小,但翻压后能改善烟叶化学成分协调性,其中烟碱降低10.55％,总氮降低33.54％,氮碱比降低25.93％,总糖增加8.59％,还原糖变化不明显,糖碱比增加21.41％,钾增加12.50％,氯降低12.00％;可提高烟叶外观质量,烤后叶片成熟度好、结构疏松、有油分、身份中等;烤烟单叶重提高15.46％,叶片厚度降低17.86％,含梗率降低5.93％;烤烟香气质、香气量和余味增加,杂气降低,感官评吸得到改善;致香成分中类胡萝卜素物质降解提高12.95％,芳香族氨基酸物质降解提高20.76％,西伯烷类物质降解提高9.59％,美拉德反应变化不明显;上等烟比例提高35.59％,每公顷产量提高5.65％,每公顷产值提高14.61％,烤烟经济形状得到提升.以烤烟套种草木樨或小麦的效果最好.

Cadmium (Cd) pollution threatens agricultural security worldwide. This study tested the efficacy of priming chemicals to decrease Cd uptake by tobacco plants (Nicotiana tabacum). After initial screening from nine different chemicals (NaCl, Cd(CH3COO)2, Cd(NO3)2, CdCl2, KHNO3, polyethylene glycol 6000 (PEG-6000), indole-3-acetic acid (IAA), ß-aminobutyric acid (BABA), and glutathione (GSH)), NaCl and PEG-6000 were further investigated because of their low risks to plant growth and efficiency to Cd reduction. Priming procedures (concentrations) were optimized for both chemicals and the best one (100 mM NaCl) was used to test both soil and hydroponic media. The results showed 31.3% lower Cd concentrations in shoots after priming with 100 mM NaCl. Phenotype parameters of the plants were also measured and showed no significant impacts of the priming procedures on the shoot biomass and the uptakes of nitrogen (N), phosphorus (P), and potassium (K), nor the photosynthetic capacity (net photosynthesis rate (Pn) and chlorophyll concentration (SPAD)). Histological observations of the roots showed a significant increase of the stele diameter after NaCl priming and a subsequent negative correlation between shoot Cd concentration and stele diameter was found after NaCl priming at different levels. This study confirmed 100 mM NaCl as an efficient priming treatment to decrease Cd uptake and the coarsening of the root stele was identified as a potential explanation for the observed decrease of Cd in tobacco shoots.

为了解干旱胁迫对烟草不同部位细胞程序化死亡的影响,以中烟100(不耐旱)和农大202(耐旱)为材料,采用2.5％PEG-6000模拟干旱,分析了不同耐旱性材料表型差异,用DNA Ladder法、TUNEL法测定烟草不同部位细胞程序化死亡发生的时间及程度差异.结果表明:(1)干旱胁迫下,农大202和中烟100的生物量、根长、根直径均较对照下降,其中中烟100下降幅度更大且与对照达到极显著差异;(2)中烟100在干旱胁迫第3天,各部位均已发生PCD,但是不同部位对干旱胁迫的响应不同,叶片、侧根的PCD发生程度相近,根尖细胞发生程度明显高于叶片及侧根;(3)根据定位观察可知侧根皮层细胞以及远离叶脉的细胞较早发生PCD;(4)烟草的耐旱性越强,PCD发生较迟,发生程度也越弱.综上所述,干旱胁迫下烟草不同部位细胞发生PCD的时间和特征是有差异的,耐旱性不同的品种发生PCD的时间也是有差异的.

为快速、无损、准确地估计烟草叶绿素含量,通过品种和氮素水平双因素试验,获得叶片数字图像和叶片叶绿素含量数据集,分析叶片可见光谱参数与叶绿素含量参数间的关系并选择最佳参数建立估测模型.结果表明,烤烟品种和氮素水平互作增加了叶绿素与光谱参数的变异性;在3类颜色指标中,NRI、R/(G+B)、(R-B)/G、(G-R)/(R+G+B)、(R-B)/(R+G+B)、ExR与叶绿素指标达到极显著相关(p<0.01),其中R/(G+B)与Chl.a、Chl.b、Chl.(a+b)之间的相关系数分别为-0.632、-0.636、-0.666,相关性表现最好;利用田间试验进行验证,R/(G+B)对叶绿素指标的预测精度最高,与Chl.a、Chl.b、Chl(a+b)之间的均方根误差值分别为0.6069、0.1567、0.7575;选择R/(G+B)作为叶绿素含量估测的最佳颜色指标.利用该方法可实现智能手机对烟草叶绿素含量进行快速测定,及时指导烟田施肥和采取合适的栽培管理措施,具有可期的应用潜力.

随着社会科技发展,创新的重要性也在不断地提高,我国也愈加重视科技成果的传化,无论是理论界还是产业界都对科技成果转化非常重视.但是通过分析实际情况可以发现,理论界并没有认识到科技成果转化过程中做好档案信息资料收集和管理的重要性,这也直接导致了很多价值较高的科研项目档案分散的保存在不同地方,甚至可能出现档案信息遗失的情况.所以,我们必须认识到科技成果转化中项目档案管理工作开展的重要性,并采取措施做好相关的档案管理工作.

为明确烟草NtTubB在烟草中的生物学功能,在烟草K326中同源克隆到1个TubB蛋白基因NtTubB,并对其基因结构、生物信息学预测、进化关系以及逆境下的表达模式进行分析.结果 表明,NtTubB基因cDNA全长为2 783 bp,其中开放阅读框2 475 bp,由3个外显子和2个内含子组成,编码443个氨基酸残基组成的亲水蛋白.NtTubB蛋白序列无信号肽和跨膜结构域,存在多个磷酸化位点,主要定位于细胞质中,序列高度保守,尤其是N端序列,含有2个保守结构域(GTPase domain和C-terminal domain),均属于Tubulin/FtsZ family家族.高级结构以α-螺旋和无规卷曲为主.进化分析表明,普通烟草NtTubB的氨基酸序列与林烟草NsTubB高度同源.逆境响应分析表明,NtTubB基因受脱落酸(ABA)、水杨酸(SA)、赤霉素(GA)、茉莉酸甲酯(MeJA)、过氧化氢(H2O2)、高盐、低温和高温诱导,暗示烟草NtTubB基因参与了多种激素和非生物胁迫的应答反应.

土壤影响着烤烟的产量、质量、香型风格及其彰显程度.认识土壤是合理利用和改良土壤的基础.本研究以我国优质烤烟典型产区四川省攀西山区攀枝花市的米易县和仁和区以及凉山州的会东县和会理县为研究区域,在综合考虑地形地貌、成土母质、土壤条件、烟叶长势和品质的基础上,在上述地区分别确定了5、5、5和4个代表性烟田,基于野外成土因素调查和剖面形态特征观察信息以及第二次土壤普查中大致对应的典型剖面理化信息,初步确立了其在中国土壤系统分类上的归属.结果表明:调查的19个代表性烟田分属富铁土、淋溶土、雏形土和新成土4个土纲,涉及7个亚纲、9个土类和11个亚类.总体来看,这些烟田的优势是土体较厚,岩石碎屑含量适宜,但劣势是耕作层质地偏黏,且部分烟田为坡旱地,存在水土流失风险.

[目的]为了研究打顶后烟叶中生长素(IAA)含量对绿原酸合成的影响.[方法]以红花大金元为试验材料,盆栽试验采用完全随机设计,利用高效液相色谱法和酶联免疫法分析烟叶IAA含量、绿原酸含量以及绿原酸合成与降解关键酶活性.[结果]苗期打顶后烟叶中内源IAA和绿原酸含量均降低;现蕾后打顶烟叶中IAA和绿原酸含量在第3天后趋于下降.通过NAA(α-Naphthalene acetic acid)和NPA(N-1-naphthylphthalamic acid)回补试验发现,打顶处理和NPA处理烟叶中内源IAA和绿原酸含量降低,过氧化物酶(POD)和多酚氧化酶(PPO)活性升高;打顶+NAA处理烟叶中内源IAA和绿原酸含量升高,POD和PPO活性降低.与未打顶处理(对照)相比,其他几个处理烟叶中苯丙氨酸解氨酶(PAL)、4-香豆酸连接酶(4CL)、肉桂酸4-羟化酶(C4H)、对-香豆酸3'-羟化酶(C3H)和羟基肉桂酰辅酶A:莽草酸/奎尼酸羟基肉桂酰转移酶(HQT)活性升高.[结论]打顶后烟叶中绿原酸含量与内源生长素含量变化密切相关,并受POD和PPO活性调控.

Drought stress is one of the main factors limiting crop production, which provokes a number of changes in plants at physiological, anatomical, biochemical and molecular level. To unravel the various mechanisms underpinning tobacco (Nicotiana tabacum L.) drought stress tolerance, we conducted a comprehensive physiological, anatomical, biochemical and transcriptome analyses of three tobacco cultivars (i.e., HongHuaDaJinYuan (H), NC55 (N) and Yun Yan-100 (Y)) seedlings that had been exposed to drought stress. As a result, H maintained higher growth in term of less reduction in plant fresh weight, dry weight and chlorophyll content as compared with N and Y. Anatomical studies unveiled that drought stress had little effect on H by maintaining proper leaf anatomy while there were significant changes in the leaf anatomy of N and Y. Similarly, H among the three varieties was the least affected variety under drought stress, with more proline content accumulation and a powerful antioxidant defense system, which mitigates the negative impacts of reactive oxygen species. The transcriptomic analysis showed that the differential genes expression between HongHuaDaJinYuan, NC55 and Yun Yan-100 were enriched in the functions of plant hormone signal transduction, starch and sucrose metabolism, and arginine and proline metabolism. Compared to N and Y, the differentially expressed genes of H displayed enhanced expression in the corresponding pathways under drought stress. Together, our findings offer insights that H was more tolerant than the other two varieties, as evidenced at physiological, biochemical, anatomical and molecular level. These findings can help us to enhance our understanding of the molecular mechanisms through the networks of various metabolic pathways mediating drought stress adaptation in tobacco.

为研究低温胁迫及恢复生长后烟苗叶形及生长素含量的动态变化规律,采用盆栽试验研究4℃低温胁迫下及低温后恢复常温生长的烟苗地上部生物量、叶面积、叶形指数、不同部位叶片生长素含量以及生长素外流蛋白家族基因NtPINs表达的变化情况.结果表明,低温胁迫下烟苗地上部生物量较同期对照组极显著减小,恢复常温后虽能继续生长但生物量仍低于同期对照组;低温后恢复生长烟苗的叶形指数极显著高于同期对照组;低温胁迫24 h时,烟苗茎尖新生叶IAA含量较对照组极显著升高,但自下而上第4张叶片的IAA含量较对照组极显著降低,恢复生长8 d时不同部位叶片IAA含量均大幅升高;qRT-PCR结果显示,低温胁迫24 h时,烟苗茎尖新生叶NtPIN1、NtPIN1b、NtPIN3、NtPIN3b、NtPIN4和NtPIN9表达水平均较同期对照极显著下调;低温下施加外源生长素α-萘乙酸(NAA)、生长素极性运输抑制剂1-萘氨甲酰苯甲酸(NPA),常温下施加NPA可明显影响烟苗的叶形指数.因此,低温胁迫导致烟苗地上部生长素从茎尖新生叶向茎基部极性运输的减少是烟苗叶片形态响应低温胁迫的生理机制之一.

Chilling stress is one of the most important environmental stresses for chilling-sensitive species.The present study conducted RNA-Seq and WGCNA analysis to clarify the correlation patterns among genes of different treatments in tobacco (Nicotiana tabacum).A total of 10,355 DEGs were found in chilling treatment relative to control treatment.Additionally, functional annotations revealed that 48 genes were found to be specifically expressed in lignin biosynthesis pathway in tobacco seedlings under chilling stress.Our results revealed that the biosynthesis of caffeoyl-CoA was regulated by HCT and C3H.Furthermore, the G-type lignin biosynthesis branch was enhanced under low temperature, which contributed to an increase in lignin content and changes in lignin composition, indicating that G-type lignin may play an important role in tobacco's resistance to chilling stress.

采用10℃积温数据对1980-2013年间攀枝花烟区热量条件进行分析,解析了攀枝花烟区10℃积温的空间格局及变化趋势,对比了不同区域及各区县间的差异,为研究区依据不同热量条件制定相应的烤烟种植与栽培制度提供数据支持.结果 表明:研究区10℃积温呈南部东区、西区及仁和县高而北部盐边县和米易县低的空间格局,在1980-2013年间,研究区10℃积温总体呈上升趋势(5.44℃/a),在空间上呈西北部盐边县高而东部低的格局.分区县比较来看,东区、西区及仁和区地处金沙江河谷,10℃积温较高且变化趋势最明显,米易县和盐边县海拔高积温低且变化趋势较低,其中米易县10℃积温变化趋势最低,由于两者纬度一致,因此积温变化曲线也相对一致.

土壤腐殖质含量和组成影响烤烟的产量和质量.中国烤烟种植空间分布广泛,植烟土壤的成土因素和土壤类型复杂多样,但有关全国尺度的植烟土壤腐殖质组分特征的研究报道甚少.采集了中国12个优质烟叶产区47个代表性县市425个典型烟田的耕层(0～30 cm)土样,测定和比较分析了土壤腐殖质组分,并进行了聚类分区.结果 表明:(1)腐殖质总碳量介于6.04～ 23.18 g·kg-1,平均为13.91 g·kg-1;腐殖酸碳量、胡敏酸碳量、胡敏素碳量、富里酸碳量以及胡富比的范围分别为3.66～ 12.23 g·kg-1、1.41～ 6.17 g·kg-1、2.38～ 10.95 g·kg-1、2.24～ 6.99 g·kg-1和0.45～ 1.03,平均分别为8.10 g·kg-1、3.22 g·kg-1、5.81 g·kg-1、4.88 g·kg-1和0.72.(2)腐殖质全碳量南岭山区显著高于其他地区,中原产区与鲁中山区显著低于其他地区;腐殖酸碳量、胡敏酸碳量和胡敏素碳量均以南岭山区为最高,鲁中山区均为最低;胡敏素含量攀西山区较高,但其他组分偏低.(3)依据腐殖质组分(6项指标)将47个县市产区分为四类地区,各类地区之间腐殖质含量和组分差异显著.