A SURVEY OF ACTIVITIES OF ENZYMES HYDROLYSING SUCROSE AND STARCH IN SOILS UNDER PASTURE

Some climatic and soil factors influencing the activities of enzymes hydrolysing sucrose and starch in New Zealand soils under pasture were studied. Amounts of reducing sugars produced on incubation of soils without added substrate were related very closely to soil organic C content. Activities of (a) enzymes hydrolysing sucrose and (b) enzymes hydrolysing starch decreased and increased, respectively, with increasing rainfall; the ratios (a)/(i) were highest in the driest groups of soils. Variations in annual rainfall and soil organic C together, but not separately, explained much of the variation in sucrose-hydrolysing activities; these activities appeared to be related more to the composition than the amount of organic matter in a soil. Variations in activity of enzymes hydrolysing starch could be explained by variations in soil organic C, clay content, and, in some cases, other factors associated with different soil groups; these activities were increased by irrigation and reduced by drainage of soils. The activity of starch-hydrolysing enzymes, compared with sucrose-hydrolysing enzymes, was relatively greater under legumes than under grasses at the same site but could differ considerably at different sites. Activities also differed under forest and pasture at adjacent sites.     

我国主要土壤剖面酶活性状况

本世纪五十年代以来,由于科学的发展以及新技术的引入,土壤酶的研究愈来愈为人们所重视。试验研究已证明,土壤酶是土壤的组成分之一。     

A STUDY OF ACTIVITIES OF ENZYMES HYDROLYSING SUCROSE AND STARCH AND OF OXYGEN UPTAKE IN A SEQUENCE OF SOILS UNDER TUSSOCK GRASSLAND

Biochemical activities were studied at three sampling dates in a sequence of four soils, ranging in altitude from 275 to 1,520 m, on schist parent material in a tussock-grassland association on the Old Man Range, Central Otago. Activities were similar under different tussock species. The uppermost part of the soil appeared to be most affected by seasonal changes because fluctuations at different sampling dates were greater in samples of topsoil from depth 1 to 7.5 cm than in samples of A, AB, and B horizons at depths approximately 4, 13, and 28 cm. Activities of enzymes without added substrate and of enzymes hydrolysing sucrose or starch generally increased with increasing altitude of the soils and were strongly correlated with organic C content and, to a lesser extent, with soil moisture content. In previous pasture surveys, enzymes hydrolysing sucrose had not been significantly correlated with organic C. Although oxygen uptakes were also positively correlated with these factors, and with numbers of viable bacteria, consistent differences between soils were not found. Differences between A and AB horizons were usually greatest in the soil at the highest altitude but, otherwise, rates of regression of biochemical activities with depth of soil were generally similar in all soils. Results may be indicative of biochemical activities in other mountain-soil sequences.     

太湖地区水稻土优势反硝化细菌的数量、组成与酶活性

本研究结果表明太湖地区主要水稻土中反硝化细菌常在百万/克干土以上,占细菌总数的50—80%。同一类型土壤中,肥力高者含菌数多于肥力低者。各类土壤中反硝化细菌数与细菌总数呈显著正相关。其优势种中,以巨大芽孢杆菌、荧光假单胞菌和施氏假单胞菌等出现的机率最高,占反硝化细菌的10—50%;地衣芽孢杆菌及坚强芽孢杆菌等出现的机率较少。具有使NO₃^-还原为N₂O的菌株和使N₂O还原为N₂的菌株,分别占供试菌株的67%和56%;使¹⁵NO₃^-异化还原为¹⁵NH₄⁺的菌株占供试菌株的92%,其中以蜡质芽孢杆菌和地衣芽孢杆菌的这种能力特别强。     

泥质海岸防护林土壤酶活性特征研究

研究了苏北淤泥质海岸防护林土壤磷酸酶活性的特点以及几种酶活性的分布规律。结果表明：（１）滨海潮土中磷酸酶以碱性磷酸酶为主,占总磷酸酶活性的６２．６％,因而可用碱性磷酸酶活性反映整个磷酸酶活性;总磷酶酶和碱性磷酸酶活性关系式为：ｙ＝－０．０４７６５＋１．６７４２６ｘ１,ｒ＝０．９７３１。（２０土壤酶活性在剖面上存在显著差异。对林地而言取样深度６０ｃｍ即满足精度要求,取样数为３－４个,当取样深度为４０     

CONCENTRATIONS AND ACTIVITIES OF IONS IN SOLUTIONS DISPLACED FROM BASALTIC SOILS

Soil solutions displaced from Antrim basaltic soils were analysed for major inorganic constituents. The solutions were nearly saturated with aluminium and phosphate but not sulphate. Iron concentrations were greatly in excess of ferric hydroxide solubility. The solutions were less concentrated than those described for soils of Britain and the U.S.A., representing a leaching environment.     

苯噻草胺对水田土壤呼吸强度和酶活性的影响

研究了除草剂苯噻草胺对水稻田土壤呼吸强度和酶活性的影响。表明苯噻草胺使用后初期刺激土壤呼吸作用但随后产生轻微抑制 ,能激活脱氢酶的活性 ,但抑制过氧化氢酶活性随后产生一定的刺激作用。苯噻草胺强烈抑制脲酶活性 ,轻微抑制蛋白酶活性 ,但对磷酸酶具有刺激作用 ,而且随苯噻草胺施用浓度的增加而刺激作用增强。苯噻草胺比上一代除草剂丁草胺所造成的对水稻田土壤呼吸强度和酶活性的影响小     

DISTRIBUTION OF CARBON DIOXIDE AND OXYGEN IN THE GAS PHASE OF AEROBIC SOILS

It is shown that, under certain conditions, the increase in carbon dioxide partial pressure is proportional to the drop in oxygen partial pressure in the gas phase in fallow soils. The principal assumptions are that respiration is unaffected by lowering of oxygen partial pressure until very low levels are reached, and that the respiration quotient is constant. Previously reported measurements of the composition of gases extracted from soil are consistent with the theory.     

转玉米ZmMPK7基因烟草响应高盐胁迫的光合特性和抗氧化酶系统分析

以烟草NC89品种野生株系(WT)和转玉米ZmMPK7基因株系为材料,在NaCl胁迫条件下,对其光合特性和抗氧化酶活性进行分析,以探讨转ZmMPK7基因烟草的耐盐性。结果表明,随盐胁迫加重,转基因烟草植株比野生型具有更高的净光合速率(Pn)、PSⅡ最大光化学效率（Fv/Fm）和叶绿素含量（Chl）,并且转ZmMPK7基因株系能提高烟草叶片抗氧化酶活性,诱导抗氧化酶 (SOD、APX、CAT和POD)活性之间协调变化。与野生型相比,转基因烟草植株MDA含量及电解质外渗量较低,膜脂过氧化较轻,其耐盐性得到改善。     

土壤氮素矿化的温度水分效应

应用一级反应动力学模型分析了不同温度、水分条件下间歇淋洗和分次提取通气培养法生成的累积净矿化氮与时间的关系。结果表明,温度对土壤氮素矿化速率常数有明显影响。间歇淋洗加砂培养的回归式为:1ogK=6.80-2497/T;不加砂培养为:1ogK＝4.19-1817／T;分次提取培养为:logK=6.47-2937／T。矿化速率常数与水分含量符合直线关系,矿化氮量随水分含量的升高而增加。温度、水分对矿化速度有明显的正交互作用。     

黑土的酶活性

近年来,土壤的熟化实质问题引起了人们越来越大的注意.这主要是因为,揭示土壤的熟化实质,有助于定向地培肥土壤和有效地调控土壤肥力的演变进程.1978年,我们在先前工作的基础上,进一步对不同开垦年限、不同熟化度黑土的熟化实质问题进行了研究.本文着重讨论黑土的酶活性及其与土壤腐殖物质和其他肥力因素的相关性.     

不同种植方式下土壤和蔬菜中氨基甲酸酯类农药残留状况研究

氨基甲酸酯类农药的蔬菜残留问题随着其广泛使用受到公众的极大关注。本研究采用高效液相色谱-柱后衍生-荧光检测法分析了苏南某市4种不同种植方式下（传统菜地、露天蔬菜基地、大棚蔬菜基地和水稻田）68个蔬菜样品和32个土壤样品中10种N-甲基氨基甲酸酯类农药（涕灭威、涕灭威砜、涕灭威亚砜、杀线威、灭多威、残杀威、克百威、3-羟基克百威、甲萘威和灭虫威）的残留量，结果表明在蔬菜中检出的氨基甲酸酯农药残留水平多处于0．2～23μgkg^-1，土壤中为0．1～10μgkg^-1；土壤中3-羟基克百威和灭虫威全部检出，其最高检测浓度分别为10μgkg^-1和1．64μgkg^-1，其他农药仅有少数检出。尤其，克百威的代谢物3-羟基克百威在土壤和蔬菜样品中均全部检出，且部分蔬菜，如空心菜、茄子和芹菜中3-羟基克百威的浓度高达0．4～4．8mgkg^-1。这可能是由蔬菜对其生物利用的有效性不同造成的。此外，不同种植方式下土壤与某些蔬菜中（西红柿、辣椒和上海青）3-羟基克百威的含量间存在一定的相关性，但统计结果表明相互间的差异并不显著。     

土壤锗污染对土壤酶活性的生态毒理效应

通过室内培养和盆栽试验,研究了土壤添加锗(Ge)对黄棕壤过氧化氢酶、脱氢酶、脲酶、碱性磷酸酶、转化酶的生态毒理效应。结果表明,在土壤Ge含量2~200 mg kg-1范围,土壤Ge对脱氢酶、碱性磷酸酶、转化酶活性抑制作用不明显。土壤Ge对土壤过氧化氢酶和脲酶活性有明显抑制作用,脲酶受Ge的抑制作用最强。土壤Ge含量与脲酶活性之间具有显著负相关,脲酶抑制率可作为Ge生态风险评价的一项生物指示物。     

不同林分土壤养分、微生物与酶活性的研究

研究了尾叶桉、马占相思、柚木、落羽杉纯林及黎蒴栲和湿地松、红荷和湿地松、黎蒴栲和加勒比松针阔混交林的土壤养分含量、微生物数量和酶活性。结果表明 :与马尾松纯林相比 ,马占相思、柚木、落羽杉纯林及针阔混交林能显著增加有机质和土壤养分 ,而尾叶桉纯林的效果随养分种类而异。黎蒴栲×湿地松混交林地及尾叶桉林地的微生物数量小于马尾松纯林地 ,其余林地的微生物数量大于后者。除了尾叶桉林地和马占相思林地外 ,其他林地的酶活性大于马尾松纯林地。总的来看 ,尾叶桉纯林改良土壤效果不佳 ,其他 6种人工林可以提高土壤肥力 ,防止地力衰退。     

铅锌银尾矿区土壤微生物活性及其群落功能多样性研究

通过对浙江省天台铅锌银尾矿区土壤微生物活性指标以及微生物群落功能多样性研究 ,结果表明 ,尾矿污染区土壤几种重金属含量比非矿区土壤有明显的增加。尾矿区土壤微生物特征发生了显著的变化 ,微生物生物量和可培养细菌数量显著降低 ,但土壤基础呼吸和微生物代谢商 (qCO2 )值却明显升高。Bi olog测试结果显示 ,随着重金属污染程度的加剧其土壤微生物群落结构发生了相应变化 ,尾矿区土壤微生物群落代谢剖面 (AWCD)及群落丰富度、多样性指数均显著低于非矿区土壤 ,且供试土壤间均达极显著水平差异 (p <0 .0 1) ,表明尾矿区重金属污染引起了土壤微生物群落功能多样性的下降 ,减少了能利用有关碳源底物的微生物数量、降低了微生物对单一碳源底物的利用能力     

水分和温度对土壤钾素释放、固定影响的初步研究

钾是植物的重要养分之一。由于土壤中存在着不同的矿物,因而产生钾的释放和固定,但这一过程受到很多因素的影响,其中水分状况是重要因素之一。多年来水分状况对钾素释放、固定影响的问题,受到了土壤研究者的注意,但是,到目前为止仍无一致的结论,例如Omuetiand^[1]等认为。用风干土测定的交换性钾能很好反映土壤供钾状况,而Luebs等^[2]则认为,以用新鲜潮湿土测定为好。为了更好的反映土壤当季的供钾水平,合理使用钾肥,以及发挥土壤钾素的潜力,因此这一问题的研究是有实践意义的,现将研究结果报告如下。