腐殖酸对烤烟根系生长和生理活性的影晌

对腐殖酸和基肥混施进行了烤烟盆栽试验。结果表明，腐殖酸能有效刺激根系的生理活性，提高根系抗坏血酸氧化酶、多酚氧化酶等呼吸酶的活性，增强根系的活力，并能有效促进烤烟根系生长，根干重、体积和长度均有提高。     

腐殖酸和饼肥对土壤微生物和烤烟产质量的影响

摘要:通过大田试验,研究了腐殖酸肥和饼肥对土壤微生物和烤烟产质量的影响。结果表明:施用适量的腐殖酸肥和饼肥可以增加土壤微生物的总量,促进烤烟根系的发育,增加烤烟地上部干物质的积累,提高烤烟的产值,协调烟叶化学成分。整个生育期,施用有机肥对烟叶的后期生长更为有利,且仅施用腐殖酸肥的效果优于仅施用饼肥,同时施用适量的腐殖酸肥和饼肥的处理效果最好。      

新型复合保水剂对半干旱区烤烟生长和生理特性的影响

为探究新型复合保水剂对半干旱地区烤烟生产的影响，通过田间试验，以不施保水剂为对照，研究传统保水剂（聚丙烯酸盐保水剂、聚乙烯醇-丙烯酸保水剂）和新型复合保水剂（生物炭复合保水剂、腐殖酸钾复合保水剂）对烤烟生长状况、碳氮代谢关键酶活性、有机酸和常规化学成分的影响。结果表明，生物炭复合保水剂和腐殖酸钾复合保水剂相较于传统保水剂更有利于提高烟叶最大叶长和烟株根系体积，促进烤烟碳氮代谢能力，提高烟叶淀粉酶（AL）、中性转化酶（NI）和硝酸还原酶（NR）活性；生物炭复合保水剂和腐殖酸钾复合保水剂显著提高烟叶非挥发性有机酸总量，其中腐殖酸钾复合保水剂增幅较大，苹果酸、柠檬酸含量较对照分别提高16.8%、29.8%和30.5%、27.9%，同时还提高了烟叶总糖、还原糖、烟碱、钾、氯含量以及糖碱比。施用新型复合保水剂更有利于促进半干旱地区烤烟生产。     

腐殖酸和饼肥对土壤微生物和烤烟产质量的影响

通过大田试验,研究了腐殖酸肥和饼肥对土壤微生物和烤烟产质量的影响.结果表明:施用适量的腐殖酸肥和饼肥可以增加土壤微生物的总量,促进烤烟根系的发育,增加烤烟地上部干物质的积累,提高烤烟的产值,协调烟叶化学成分.整个生育期,施用有机肥对烟叶的后期生长更为有利,且仅施用腐殖酸肥的效果优于仅施用饼肥,同时施用适量的腐殖酸肥和饼肥的处理效果最好.     

聚丙烯酸盐类改良剂对土壤理化性状及烤烟根系生长的影响

为探讨聚丙烯酸盐类土壤改良剂单施和复配作用下的土壤理化性状及烤烟根系生长变化,采用大田试验研究了土壤改良剂对植烟土壤肥力、含水量、容重及烤烟根系指标的影响。结果表明:(1)聚丙烯酰胺+腐殖酸钾处理的土壤有机质、碱解氮、速效磷含量最高,聚丙烯酸钾+腐殖酸钾处理的土壤速效钾含量最高;(2)在提高土壤含水率以及降低土壤容重上,聚丙烯酰胺+腐殖酸钾处理效果最好,各土层土壤含水率的提高幅度及容重的降低幅度均表现为20~40 cm10~20 cm0~10 cm;(3)聚丙烯酰胺+腐殖酸钾处理的根长、根体积、根干重和根冠比显著高于其他处理,施用土壤改良剂也明显提高了20~40 cm土层根系生物量的比重。总的来看,施用土壤改良剂能改善土壤理化性状,促进根系生长发育,以聚丙烯酰胺+腐殖酸钾处理效果最佳。     

汽爆烟秆替代基质对烤烟漂浮育苗烟苗素质的影响

为研究汽爆烟秆替代商品基质对烤烟漂浮育苗烟苗素质的影响,以100%商品基质为对照,采用不同配比汽爆烟秆与商品基质混合进行烤烟漂浮育苗试验,结果表明,汽爆烟秆替代商品基质处理烟苗的出苗率在95%以上,与对照无明显差异,成苗率高于对照;成苗时烟苗茎高、叶片数及地上部分鲜干重优于对照,而茎围、根系条数、根鲜干重及叶绿素含量、根系活力、超氧化物歧化酶(SOD)活性和过氧化酶(POD)活性与对照无明显差异;汽爆烟秆替代商品基质处理基质成本比对照降低11.88～47.71元/hm²。总体而言,汽爆烟秆可以代替商品基质进行烤烟漂浮育苗。     

饼肥和腐殖酸对植烟土壤养分及烤烟生长影响

１９９７～１９９８年通过盆栽试验,对纯施化肥、饼肥与化肥配合、不同种类腐殖酸与化肥配合情况下烟叶土壤营养状况、烤烟生长状况和烤后烟叶化学成分进行分析研究。结果表明：施用腐殖酸和饼肥可使土壤ｐＨ值下降,改善水肥条件,优化烟草生长环境,从而促进烟草早发快长;烟叶干物质积累和烟草根系体积明显增加,并对后期叶绿素ａ降解和成熟落黄有较好的作用;能够促使烟叶化学成分更加协调,提高烟叶质量。结果还表明,Ａ类腐殖酸优于其它腐殖酸,且与饼肥施用效果近似,但它们在有些方面的作用各有侧重     

腐殖酸肥对百色植烟土壤养分和烤烟香气质量的影响

2010-2011年采用大田试验,研究了施用腐殖酸肥对百色植烟土壤养分和烤烟香气质量的影响。结果表明,施用腐殖酸肥可提高土壤速效钾、有机质等主要养分含量,幵能明显提高烤烟的经济效益,以腐殖酸肥用量为150 kg/hm^2的烤烟经济性状指标最高。施用腐殖酸肥能改善烟叶化学品质,烟叶化学成分含量适宜、比例协调,主要致香物质含量和总致香物质含量均明显高于不施肥处理,烟叶评吸得分均较高。因此,生产上建议百色烟区偏碱性植烟土壤腐殖酸肥用量为150 kg/hm^2。     

腐殖酸对土壤环境和烤烟矿质吸收影响的研究

采用烤烟盆栽和大田试验相结合的方法，进行了腐殖酸对土壤环境和烤烟矿质营养影响的研究。试验结果表明，腐殖酸可在一定程度上降低土壤pH值；增加土壤有机质含量2．68％－18．70％；土壤中的蔗糖酶和磷酸酶活性分别提高6．03％－51．87％和1．99％－22．93％，土壤营养状况随之改善。在一定用量腐殖酸的作用下，烤烟体内的矿质营养得到改善，烤后烟叶的磷、钾、硼、镁、锌等矿质元素含量比对照都有所提高，腐殖酸可明显提高烤烟上等烟比例、单叶重、产量和产值，使烟叶内在化学成分更趋协调，各项品质指标更趋合理。烤烟生产中，腐殖酸最适用量为120kg/hm^2。     

烟秆有机肥对烤烟根系发育和矿质元素含量的影响

为探索烟秆有机肥(发酵烟秆+芝麻饼肥+腐植酸)对烤烟根系发育、烟叶矿质营养和烟叶质量的影响,采用盆栽试验设置不同用量烟秆有机肥处理,研究其对烤烟根系发育和矿质元素的影响。结果表明,施用烟秆有机肥对烤烟根系生物量和生理活性提高作用较大,在旺长期和圆顶期促进作用最明显,表现为根体积增长率、根干重增长率、根系活力及根系吸收面积在此时期出现高峰,以添加500 g/盆的处理效果最好,其根体积、根干重、根系活力和根系总吸收面积于移栽后75 d分别比对照提高了60.77%、114.76%、53.12%和148.36%;烟秆有机肥配施促进烤烟对矿质元素的吸收,特别是对磷、锌、铁、锰含量提高效应较显著。综合考虑,添加烟秆有机肥500 g/盆的处理最佳,为培育烟株健壮根系,均衡烤烟矿质营养及烟秆的还田应用提供参考。     

Selective electrochemical detection of ionic and neutral species using films of Suwannee River humic acid

An electroanalytical method has been developed to investigate the uptake of redox-active species by the humic acid substances. The Suwannee River humic acid (SHA) films were first cast on a glassy carbon electrode using an electrophoretic approach. The binding of a series of redox-active species to these SHA films was then probed using cyclic voltammetry at a rotating disk electrode. Neutral molecules such as hydroquinone and cationic species such as methyl viologen are able to bind with the humic membrane and exhibit high redox activity within the film. On the other hand, anionic species such as ferrocyanide are unable to attach themselves to the SHA films and thus exhibit negligible electrochemical activity. Cyclic voltammetric study of SHA films has also facilitated the determination of the partitioning constants and identification of the effect of coadsorbed ions (Ca2+) on the binding of redox species. The electroanalytical method described in this study opens up new avenues to examine the interactions and transport of charged species in a humic acid environment.     

13C NMR analysis of biologically produced pyrene residues by Mycobacterium sp. KMS in the presence of humic acid

Cultures of the pyrene degrading Mycobacterium sp. KMS were incubated with [4-13C]pyrene or [4,5,9,10-14C]pyrene with and without a soil humic acid standard to characterize the chemical nature of the produced residues and evaluate the potential for bonding reactions with humic acid. Cultures were subjected to a "humic acid/ humin" separation at acidic pH, a duplicate separation followed by solvent extraction of the humic acid/humin fraction, and a high pH separation. 13C NMR analysis was conducted on the resulting solid extracts. Results indicated that the activity associated with solid extracts did not depend on pH and that approximately 10% of the added activity was not removed from the solid humic acid/humin fraction by solvent extraction. 13C NMR analysis supported the conclusion that the majority of pyrene metabolites were incorporated into cellular material. Some evidence wasfound for metabolite reaction with the added humic material, but this did not appear to be a primary fate mechanism.     

Cadmium bioavailability and accumulation in the presence of humic acid to the zebra mussel, Dreissena polymorpha

Metal speciation in aquatic systems is mainly determined by the type and concentration of ligands present in solution. A very important group of complexing agents is dissolved organic matter (DOM), e.g., humic and fulvic acids. According to the free-ion activity model, only the free metal ion is available to biota. Nevertheless, DOM has been reported to decrease or increase metal uptake, leading to uncertainty concerning the bioavailability of metal-DOM complexes. In this work the effect of Aldrich humic acid on cadmium accumulation by the zebra mussel, Dreissena polymorpha, was studied under laboratory conditions. Mussels, collected in a drinking water reservoir, were exposed to varying environmentally relevant concentrations of cadmium in the presence and absence of humic acid. Cadmium concentrations in the mussel tissues were analyzed, and measurements with a cadmium-ion-selective electrode were made to determine the free cadmium ion activity in the exposure waters. The uptake of humic acid by the zebra mussels was measured by the decrease of the total organic carbon (TOC) concentration in the water over time. The free cadmium ion activity in the water decreased from 51.6% to 19.9% of the total cadmium concentration in the presence of humic acid. This decrease by a factor of 2.6 resulted in a decrease in the cadmium uptake rate in the soft tissue of zebra mussels from 12.9 to 7.9 nmol/g dry wt/day, which corresponds to a decrease by a factor of 1.6. This implies that cadmium uptake rates were higher than predicted by the free-ion activity model and indicates that cadmium-humic acid complexes are partly available to zebra mussels.     

维生素AD结合钙处理对番茄贮藏期硬度的影响

以辽园多丽号番茄为试材,不同浓度维生素AD结合腐植酸钙处理对番茄贮藏期硬度的影响。各处理番茄果实硬度贮藏期间总体均呈下降趋势,1%维生素AD与0.5%腐植酸钙结合处理的果实硬度为4.649kg/cm2,比单喷施腐植酸钙处理高出26%,比对照高64.76%,原果胶含量逐渐下降,可溶性果胶总体上呈上升趋势。果胶酶,纤维素酶活性总体呈逐渐上升趋势,1%维生素AD与0.5%腐植酸钙结合处理果胶酶含量最低为2.13μg/g·h,比0.5%腐植酸钙处理低8.5%,比对照低43.1%。贮藏结束时,纤维素酶活性为1.963μg/g·h。总体上1%维生素AD与0.5%腐植酸钙结合处理的效果最好,提高了果实的硬度,从而提高了番茄的耐贮性。     

Noncovalent interactions between monoaromatic compounds and dissolved humic acids: a deuterium NMR T1 relaxation study

Deuterium nuclear magnetic resonance spectroscopy (2H NMR) spin-lattice relaxation (T1) experiments were used to examine solution-phase, noncovalent interactions between deuterated monoaromatic compounds (phenol-d5, pyridine-d5, benzene-d6) and Suwannee River, soil, and peat humic acids. Noncovalent interactions, in aqueous solution, were examined as a function of solution pH, monoaromatic hydrocarbon functional groups, and humic acid identity. Benzene interacted with dissolved humic acids at all pH values; however, these interactions increased with decreasing pH and generally were proportional with the humic acid percent aromaticity. Pyridine behaved similarly as benzene; however, two modes of interaction between pyridine and humic acids were detected as a function of pH and humic acid type: bonding with the lone pair of electrons of pyridine's nitrogen and pi-pi interactions between the aromatic ring of pyridine and aromatic components of humic acid. The latter interaction was favored by increasing humic acid percent aromaticity and decreasing solution pH. On the other hand, because of its strong capacity for hydrogen bonding, phenol interacted preferentially with water, except at pH values 5 or lower and with humic acids with 45% or greater aromaticity. Under these conditions, strong interactions between phenol and humic acids were observed. These results demonstrate that solution-phase, noncovalent interactions between monoaromatic compounds and humic acids are a function of solution pH, percent aromaticity, and the monoaromatic functional group.     

On the acid-base properties of humic acid in soil

Humic acid was isolated from three contrasting organic-rich soils and acid-base titrations performed over a range of ionic strengths. Results obtained were unlike most humic acid data sets; they showed a greater ionic strength dependency at low pH than at high pH. Forward- and back-titrations with the base and acid revealed hysteresis, particularly at low pH. Previous authors attributed this type of hysteresis to humic acid aggregates-created during the isolation procedure-being redissolved during titration as the pH increased and regarded the results as artificial. However, forward- and back-titrations with organic-rich soils also demonstrated a similar hysteretic behavior. These observations indicate (i) that titrations of humic acid in aggregated form (as opposed to the more usual dissolved form) are more representative of the acid-base properties of humic acid in soil and (ii) that the ionic strength dependency of proton binding in humic acid is related to its degree of aggregation. Thus, the current use of models based on data from dissolved humic substances to predictthe acid-base properties of humic acid in soil under environmental conditions may be flawed and could substantially overestimate their acid buffering capacity.     

紫甘薯多酚氧化酶性质研究

采用含有30 mmol/L Vc的0.01 mol/L磷酸盐缓冲液从紫甘薯中提取多酚氧化酶(PPO),用分光光度法对紫甘薯中多酚氧化酶的酶学特性进行了系统的研究,其中包括PPO的活力测定、热稳定性、pH稳定性以及pH、温度、抑制剂对PPO活力的影响。实验结果表明,多酚氧化酶催化反应的最佳条件为:温度25℃,pH 7.0,NaHSO3和Vc对酶活力有很强的抑制作用。     

几种抑制剂对小麦多酚氧化酶活性抑制效果研究

使用3-吗啉丙磺酸(MOPS)缓冲液从全麦粉中提取多酚氧化酶(PPO),以邻苯二酚为底物,研究不同抑制剂在不同浓度下对PPO的抑制作用。结果表明抑制剂浓度为1.0 mmol/L时,各种抑制剂的作用效果分别为:L-抗环血酸90.6%,L-半胱氨酸86.5%,NaHSO3 84%,曲酸75.5%。L-抗环血酸、L-半胱氨酸、NaHSO3、曲酸几种抑制剂浓度减小抑制作用降低。响应面分析得到的L-抗坏血酸、L-半胱氨酸和NaH-SO3最佳抑制浓度组合为:L-抗坏血酸0.4 mmol/L,L-半胱氨酸0.11 mmol/L,NaHSO3 0.25 mmol/L,抑制作用为82.03%。     

Cross-coupling of sulfonamide antimicrobial agents with model humic constituents

The oxidative cross-coupling of sulfonamide antimicrobials to constituents of natural organic matter was investigated. Sulfonamide antimicrobials were incubated with surrogate humic constituents in the absence and presence of phenoloxidases (viz., peroxidase, laccase, and tyrosinase) or acid birnessite. Substituted phenols were chosen as simple model constituents to determine the structures in humic substances important for cross-coupling reactions. The extent of sulfonamide transformation was evaluated by the disappearance of the parent compound from solution. Incubation with phenoloxidases in the absence of substituted phenols resulted in little or no sulfonamide transformation. In contrast to this, direct oxidation of sulfonamides by acid birnessite was significant. Inclusion of o-diphenols and 2,6-dimethoxyphenols in reaction mixtures resulted in significant phenoloxidase-mediated transformation of sulfonamides and enhanced antimicrobial transformation in the presence of acid birnessite. Phenolic compounds with other substitution patterns were less effective in promoting sulfonamide transformation. Nuclear magnetic resonance spectroscopy experiments provided direct evidence of peroxidase-mediated covalent cross-coupling of sulfamethazine with syringic and protocatechuic acids. Our results indicate that sulfonamide antimicrobials may be chemically incorporated into humic substances. This may result in their diminished mobility, bioavailability, and biological activity.