不同改良方法对盐碱土壤氮素营养状况的影响

采用浅耕翻、施用磷石膏、施用糠醛渣、施用有机肥、建植星星草人工草地或星星草+羊草人工草地等不同改良方法对盐碱土壤氮素营养影响的研究结果表明,不同改良方法与浅耕翻相比能不同程度地提高土壤全氮含量、碱解氮含量、氨化强度、固氮强度、蛋白酶活性、脲酶活性、硝酸还原酶活性和亚硝酸还原酶活性。其中,浅耕+有机肥+星星草+羊草处理对所测定盐碱土壤氮素营养及相关酶活性指标增加明显,同时,盐碱土壤氮素营养各指标间存在着一定的相关关系。     

不同改良方法对盐碱土壤磷素营养的影响

采用浅耕翻、施用磷石膏、施用糠醛渣、施用有机肥、建植星星草人工草地或星星草+羊草人工草地等不同改良方法对盐碱土壤磷素营养影响的研究结果表明, 不同改良方法能不同程度的提高土壤全磷、速效磷、有机磷、无机磷含量和磷酸酶活性, 其中浅耕+有机肥+星星草+羊草处理与浅耕相比土壤磷素各指标增加显著, 盐碱土壤磷素营养各指标间存在着一定的相关关系。     

青藏高原不同高寒草地类型土壤酶活性及其影响因子

土壤酶活性作为生态系统养分循环的关键因素, 是反映土壤质量和生态系统功能的重要指标, 但是关于高寒草地生态系统中不同草地类型间酶活性的差异研究还很少。因此, 该研究在藏北高寒草地选择高寒草甸、高寒草原、高寒草甸草原、高寒荒漠草原和高寒荒漠5种草地类型进行野外原位调查和采样, 测定了涉及碳(C)、氮(N)和磷(P)循环的14种酶的活性, 并建立了高寒草地酶活性与土壤微生物和土壤理化性质等环境因子的关系。结果表明: C循环酶(蔗糖酶、纤维素酶、β-葡萄糖苷酶、多酚氧化酶和过氧化物酶)和P循环酶(碱性磷酸酶)在不同高寒草地类型间活性差异明显, N循环酶中仅芳香氨基酶和亚硝酸盐还原酶两种酶在不同高寒草地类型间活性差异明显。同时, C、N和P循环酶之间存在一定的相关关系, 其中, 蔗糖酶和碱性磷酸酶、纤维素酶和α-乙酰氨基葡萄糖苷酶活性显著正相关, 多酚氧化酶与亚硝酸还原酶和β-乙酰氨基葡萄糖苷酶活性显著负相关。在测定的19个环境指标中, 土壤有机质(SOM)含量、革兰氏阴性菌数量、土壤N和P含量计量比、革兰氏阳性菌数量、细菌数量、放线菌数量、全氮含量、真菌数量是影响土壤酶活性的关键因子, 且SOM含量的影响最大(解释量为11.9%)。综上所述, 不同高寒草地类型间C循环酶、P循环酶和两种N循环酶(芳香氨基酶和亚硝酸还原酶)活性差异显著, SOM含量、微生物数量和N含量等是影响高寒草地生态系统土壤酶活性的关键因子。     

种植星星草对盐碱草地土壤养分状况的改良作用

对人工种植在碱斑草地上的星星草在不同年份相同生育期的土壤养分状况进行研究, 并与天然状况的星星草地在各个生育期的土壤养分相比较。种植星星草后, 随着星星草种植年限的增加, 0~10cm 土壤中:有机质含量和土壤全氮含量呈上升趋势, 土壤全磷含量略有增加, 土壤全钾含量变化不明显;而土壤全钠含量、全钙含量以及土壤全镁含量都有不同程度的降低。     

放牧高寒嵩草草地不同演替阶段土壤酶活性及养分演变特征

以高寒草地演替序列禾草-矮嵩草群落、矮嵩草群落、加厚期小嵩草群落、开裂期小嵩草群落和杂类草-黑土型次生裸地为对象,研究多稳态放牧高寒草地土壤酶活性演变及其与养分的关联性.结果表明:随退化演替推进,植被盖度和地上生物量依次降低,而地下生物量在加厚期和开裂期小嵩草群落达到高峰.土壤蔗糖酶、脲酶、纤维素酶、碱性磷酸酶和芳基硫酸酯酶活性在土壤表层(0~10 cm)高于亚表层(10~20 cm),而几丁质酶相反;纤维素酶、碱性磷酸酶和芳基硫酸酯酶在禾草-矮嵩草群落最高,杂类草-黑土型次生裸地最低,加厚期小嵩草群落略有升高;几丁质酶在中间3个阶段均显示较高活性;脲酶和蔗糖酶在后期杂类草-黑土型次生裸地阶段明显升高.土壤水分、铵态氮、碱解氮、全氮、全碳和有机碳随退化演替依次递减,但硝态氮和速效磷在后期两阶段回升.除几丁质酶外,其他酶均与速效磷、铵态氮、碱解氮、全碳和有机碳呈正相关,与pH呈负相关;纤维素酶、碱性磷酸酶和芳基硫酸酯酶还与土壤水分和全氮呈正相关;影响土壤酶活性的主控因子为速效磷和铵态氮.高寒草地土壤酶受放牧退化演替影响呈现不同演变趋势,酶活性与土壤养分存在相互协同作用,但重度退化的极端环境也可能会激发与氮、碳养分转化相关的土壤酶活性.     

黄土高原不同植被带土壤团聚体有机碳和酶活性的粒径分布特征

为探究土壤中各粒级团聚体不同形态有机碳和酶活性的分布特征,以黄土高原延河流域森林带、森林草原带、草原带土壤为对象,研究了不同粒级团聚体总有机碳、易氧化碳和腐殖质碳含量,以及纤维素酶、β-D葡糖苷酶、过氧化物酶、蔗糖酶和脲酶活性,分析了土壤团聚体有机碳及其组分与酶活性之间的相关关系.结果表明： 3种植被带土壤团聚体有机碳及其组分含量表现为森林带＞草原带＞森林草原带,3种形态有机碳含量在0.25～2 mm粒径均最高;不同植被带土壤团聚体有机碳及其组分含量和酶活性在0～10 cm土层大于10～20 cm土层;3种植被带纤维素酶、β-D葡糖苷酶、蔗糖酶和脲酶活性表现为森林带＞草原带＞森林草原带,过氧化物酶活性表现为森林带＞森林草原带＞草原带;3种植被带土壤中各种酶活性随着粒径的减小呈递增趋势.土壤纤维素酶、过氧化物酶、蔗糖酶和脲酶活性与团聚体各种形态碳含量均呈显著正相关.
     

玉米生长期间土壤微生物量与土壤酶变化及其相关性研究

研究了玉米生长期间土壤微生物量碳、氮与土壤过氧化氢酶、蔗糖酶、脲酶、蛋白酶活性变化及其相关性．结果表明，玉米生长前期和中期，土壤微生物量碳、氮及酶活性迅速上升，并逐渐达到最大值；玉米生长后期，土壤微生物量碳、氮、酶活性下降至某一值后并逐渐趋于平稳．几种处理相比较，以秸秆＋尿素处理的土壤微生物量碳、氮及酶活性为最大．除玉米生长后期，土壤微生物量碳、氮与碱解氮、活性腐殖质、土壤ｐＨ不相关外，土壤微生物量碳、氮与土壤过氧化氢酶、蔗糖酶、脲酶、蛋白酶活性及速效养分在玉米生长期间均相关或极相关     

退化高寒草原土壤生物学性质的变化

对藏北退化高寒草原的土壤生物学性质研究表明:轻度退化草地2~10cm土层微生物(细菌、真菌、放线菌)数量与生物量(碳、氮)、土壤酶(纤维素酶、脲酶、碱性磷酸酶)活性和有机质总体上高于正常草地,中度、严重退化草地则均呈显著降低趋势.微生物生物量碳氮比(BC/BN)与土壤全碳、全氮比(TC/TN)呈极显著正相关(r=0.9088,P≤0.01;n=4);与正常草地相比,轻度、中度退化草地BC/TC、BN/TN值均呈上升趋势,而严重退化草地则呈明显下降趋势.土壤微生物生物量与土壤酶活性呈极显著或显著正相关,但二者均与土壤放线菌数量呈不同程度的负相关;2~10cm土层有机质与土壤微生物生物量、土壤酶活性均呈极显著或显著正相关;随草地退化的加剧,2~10cm和11~20cm土层腐殖质碳占土壤有机碳比重,以及胡敏酸碳占土壤腐殖质碳比重均较正常草地明显上升.     

科尔沁沙地草地营造樟子松人工林对土壤化学和生物学性状的影响

以科尔沁沙地东南缘沙质草地和不同年龄樟子松（Pinus sylvestris var. mongolica）人工林（15、24和30年生）为对象,研究草地造林对土壤pH,土壤C、N、P含量,无机N（铵态氮、硝态氮）含量,C、N矿化速率,微生物生物量C含量以及土壤酶（脲酶、转化酶和过氧化氢酶）活性的影响.结果表明：草地造林初期,林地土壤C、N、P含量逐渐降低,随着林龄增加而逐渐恢复;与草地相比,24年生樟子松人工林土壤C、N、P含量最低,分别下降29%、34%和33%,而30年生樟子松人工林土壤C和N含量与草地差异不显著.草地造林能够影响土壤无机N存在形式,使土壤铵态氮含量逐渐增加,硝态氮含量下降.草地造林对土壤潜在N矿化速率和硝化速率影响不显著,但能够改变土壤C矿化速率,不同林龄樟子松人工林土壤C矿化速率依次为：24年生>30年生>草地>15年生.草地造林初期,土壤微生物生物量C含量和土壤转化酶活性明显降低,随着林龄的增加又逐渐增加;草地造林对土壤脲酶活性影响不显著,而使土壤过氧化氢酶活性逐渐增加.科尔沁沙地草地造林能够显著改变土壤化学和生物学性状,且随着林龄的变化而有所差异.     

内蒙半干旱低山区不同纯林土壤腐殖质分异特征及其与其他生物化学性质的关系

纯林土壤腐殖质含量及其构成是否会因枯落叶组成的单一性和单优群落环境的特殊性而发生分异变化是关系到森林可持续经营的关键问题.本文以内蒙半干旱低山区的6种典型纯林为研究对象,研究了不同树种纯林土壤腐殖质分异特征及其与其他生物化学性质的关系.结果表明：云杉和白桦林地土壤的腐殖质含量、缩合程度和稳定性均较高,其次为小叶杨和落叶松林地,再次为白榆林地,而油松林地土壤的腐殖质含量和缩合程度均最低、稳定性最差.土壤微生物生物量和磷酸酶活性与腐殖质各组分的积累及其稳定性存在相互促进作用;过氧化氢酶和脱氢酶活性则与土壤腐殖质存在相互抑制作用,且脱氢酶活性的提高可能破坏腐殖质的稳定性.速效N含量与腐殖质积累及其稳定性呈正相关,而全量Cu、Fe、Zn含量与腐殖质呈负相关,全Cu、Fe的增加可能会破坏腐殖质的稳定性.纯林环境及其枯落叶性质的特殊性是造成腐殖质分异的重要原因,混交改造或增加林下植被是改善土壤腐殖质构成的根本措施.     

模拟氮沉降及经营方式对毛竹林土壤酶活性的影响

研究粗放经营和集约经营条件下毛竹林蔗糖酶、纤维素酶、硝酸还原酶、脲酶和过氧化氢酶5种土壤酶活性对4种氮沉降水平(0、30、60和90 kg·hm^-2·a^-1)的响应.结果表明:与粗放经营相比,集约经营分别显著提高土壤蔗糖酶、纤维素酶和脲酶活性55.5%、112.9%和28.6%,显著抑制硝酸还原酶活性31.5%,对过氧化氢酶活性的影响不显著.氮沉降显著抑制粗放和集约经营方式下毛竹林蔗糖酶活性20.0%～49.4%和36.2%～45.1%、纤维素酶活性20.5%～46.3%和18.3%～49.0%、硝酸还原酶活性67.9%～85.2%和15.2%～34.2%,以及集约经营毛竹林脲酶活性23.1%～47.6%,显著增加了粗放经营毛竹林土壤脲酶活性8.1%～50.6%,对过氧化氢酶活性的影响不显著.氮沉降与经营方式的复合作用除对过氧化氢酶活性的影响不显著外,对其他4种土壤酶活性的影响均达到显著水平.     

Enzymatic activity of the rhizosphere and soils in the East Siberia area

The methods for the determination of peroxidase, polyphenoloxidase and dehydrase activity both in the soil and rhizosphere of several plants of two very different landscapes of East Siberia are described and an attempt made to find a correlation between these findings and humus content in the soil. A clear relationships was not determined which could be explained by the very complicated nature of soil redoxase activity.     

Changes in peroxidase and IAA oxidase activities during cell elongation in Phaseolus hypocotyls

Cytoplasmic and salt-extracted peroxidase and IAA oxidase activities were studied in Phaseolus vulgaris hypocotyls treated with gibberellic acid (GA, 200 μM), naphthyl acetic acid (NAA, 100 μM) and distilled water control (DW). Peroxidase activity was assayed with four hydrogen donors during the initial phase of hypocotyl elongation. Though peroxidase activity showed a decreasing trend with time in all the hydrogen donors studied; considerable variation with different hydrogen donors was observed. NAA had maximum peroxidase activity as compared to DW or GA treatment. The activity showed a clear inverse correlation with hypocotyl growth. IAA oxidase activity showed a similar trend with growth as peroxidase activity. A highly significant correlation was observed between peroxidase and IAA oxidase activities and high molecular weight xyloglucan content (P<0.001). Finally, the possible role of peroxidase and IAA oxidase activities in hypocotyl elongation growth is discussed.     

超临界CO2流体对纤维素酶催化反应的影响

超临界二氧化碳流体预处理对纤维素超分子结构及纤维素酶催化反应有重要影响。一定含水量的微晶纤维素用SC-CO2在10MPa,50℃处理30min,其结构发生了有利于进一步被酶解的变化。上述超临界条件单独作用于纤维素酶时,并未造成酶催化活力的降低;但与纤维素共同进行SC—CO2处理时,纤维素酶则失去催化活性,但这种处理却能提高纤维素进一步被酶解的效率。一定范围内处理时的酶用量与酶解效率的增加正相关。纤维素的含水量对SC-CO2处理后的酶解效率有显影响。     

Salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from Trichoderma longibrachiatum

Infiltration of cellulase (EC 3.2.1.4) from Trichoderma longibrachiatum into melon (Cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. An oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (SA) signaling pathways leading to marked induction of peroxidase and chitinase activities. The treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase and chitinase activities, but the oxidative burst and SA production were not observed. Co-infiltration of aminoethoxyvinil-glycine (an ethylene inhibitor) with the active cellulase did not affect the high increase of peroxidase and chitinase activities. In contrast, co-infiltration of aminoethoxyvinil-glycine with the denatured enzyme blocked peroxidase and chitinase activities. Our data suggest that the SA pathway (induced by the cellulase activity) and ethylene pathway (induced by heat-denatured and active protein) together coordinate the activation of defense mechanisms. We found a partial interaction between both signaling pathways since SA caused an inhibition of the ethylene production and a decrease in peroxidase activity when co-infiltrated with denatured cellulase. Treatments with active or denatured cellulase caused a reduction in powdery mildew (Sphaerotheca fuliginea) disease.     

The antagonistic action of Trichoderma sp. hyphae to Lentinula edodes hyphae changes lignocellulotytic activities during cultivation in wheat straw

Lentinula edodes (Berk.) Pegler was cultivated in sterilized or pasteurized wheat straw both with and without inoculation with Trichoderma sp. Enhancements of -mannosidase and laccase activities and lowering of Mn-dependent peroxidase activity were observed seven days after inoculation in substrates inoculated with Trichoderma sp. These enzymes were not produced by Trichoderma sp. Most of the polysaccharidase activities were higher in substrates with Trichoderma sp. than in absence of Trichoderma sp. The area of the substrate contaminated with T. harzianum significantly correlated with cellulase, laccase and Mn-dependent peroxidase activities measured in the substrate. The increase of cellulase activity was due to enzymes produced by Trichoderma sp. and the decrease of Mn-dependent peroxidase activity was due to diminished growth of L. edodes. The stimulation of laccase activity was linked with the formation of brown lines (oxidation of polyphenols) at the contact between the mycelia of the two antagonists.