Effects of a cadmium-contaminated sewage sludge compost on dynamics of organic matter and microbial activity in an arid soil

 An incubation experiment lasting 120 days was carried out to ascertain the effect on the soil microbial activity and organic matter mineralization of adding a sewage sludge compost contaminated with two different levels of Cd to an arid soil. Two composts, with a low (2 mg kg^–1) and high (815 mg kg^–1) Cd content, respectively, were used in this experiment. Both composts increased the total organic C, humic substance and water-soluble C contents, the beneficial effects still being noticeable after 120 days of incubation. The most labile C fraction (water-soluble C) was the most sensitive to the high Cd content. The high Cd concentration decreased soil microbial biomass C and stimulated the metabolic activity of the microbial biomass, the metabolic quotient (qCO₂) revealing itself to be a very sensitive index of the stress that the incorporation of a Cd-contaminated sewage sludge compost causes in a soil. The effect of Cd contamination on enzyme activities (urease, protease that hydrolyse N-α-benzoil-l-arginamide, phosphatase, and β-glucosidase) depended on the enzyme studied. Received: 10 September 1997     

榆叶梅花粉贮藏及生活力的测定

对不同品种的榆叶梅新鲜花粉及贮藏后花粉的生活力进行测定的结果表明：品种不同，花粉生活力及耐贮力均不相同，其中单辨品种的生活力和耐贮力最强。榆叶梅花粉最适萌发培养基成分为15％蔗糖 2％琼脂。花粉的适宜贮藏条件为0-4℃低温黑暗条件。     

固始鸡孵化期间蛋壳内钙鳞含量变化规律研究

对固始鸡种蛋孵化期间蛋壳中钙、磷含量进行了测定,结果表明：孵化期间蛋壳内钙、磷含量变化呈现不同规律。0~6胚龄,蛋壳中钙、磷变化均不明显;从12胚龄开始,钙含量突然降低,并以递增趋势持续至21胚龄;磷含量明显变化是从9胚龄开始,12胚龄达最大,随后逐渐降低,18~21胚龄保持不变,所以6~18胚龄是蛋壳中磷的主要转移期;同时,各胚龄阶段蛋壳中钙、磷比例也呈规律性变化。     

秸秆还田室内培养对土壤微团聚体的影响试验

采用秸秆还田室内培养试验,向土壤中添加4%不同形态玉米秸秆和根系进行室内培养腐解转化,探讨不同土壤圈对微团聚体的作用。结果表明：相同处理,不同圈数,从内层（0）到外层（7）,粒径为0.05～0.02mm和0.02～0.002mm依次增加,而＜0.002mm及＞0.25mm则表现为依次降低。可知：添加有机物降低了粒径0.05～0.02mm和0.02～0.002mm微团聚体含量,增加了＜0.002mm及＞0.25mm团聚体含量;相同圈土壤,不同处理间,团聚体变化最为明显的为N2处理,故各处理间比较,添加秸秆粉末对土壤微团聚体含量影响最为明显。由此可知,添加秸秆对土壤微团聚体的形成具有明显作用,为秸秆还田培肥土壤提供理论依据和技术参考。     

Effect of timing of application of municipal solid waste compost on N availability for crops in central Spain

To calculate the correct nitrogen fertilizer rate for crops and the possibility of using municipal solid waste (MSW) compost as an organic amendment, nitrogen mineralization rates were studied by laboratory incubation and field measurements in a soil in central Spain. Nitrogen mineralization rates were studied in a 250-day laboratory soil incubation with two treatments: with and without compost, incubated at 28°C and a moisture content of 70% of field capacity. Three phases are described: (1) no increase in the mineral nitrogen content, (2) a linear increase in the mineral N fraction and, finally, (3) a linear, parallel increase in both mineral N and easily mineralizable organic N fractions. Incubation data were fitted to three different equations. The exponential model proposed by Stanford and Smith (1972) was selected to predict field N mineralization rates. The field experiment was performed using a crop of maize with three treatments: compost applied in February (before sowing), compost applied during sowing and a control (without compost application): sampling was carried out over 14 months. Soil water content was measured periodically. Soil with compost applied in February showed 1.9 and 1.4 times more available nitrogen than soil without compost and compost at sowing, respectively, for the month of maximum accumulation. These results suggest that compost amendments must be applied before sowing. Compost applications were shown to supply the available nitrogen for spring crops. A simulation model showed satisfactory agreement with field data, after correction for soil temperature and water content. Received: 22 July 1996     

Growth and cocoon production of Drawidia nepalensis (Oligochaeta)

Summary The biology of the vermicomposting species, Drawidia nepalensis Mich. is poorly understood. We therefore studied the growth of this species at 25°C in urine-free cow and horse manure. The rate of maturation and cocoon production were studied under conditions of favourable moisture and nutrition over a period of 240 days. The results showed that D. nepalensis grew relatively slowly in comparison to other vermicomposting species, and that copulation was not a prerequisite for the production of viable cocoons, indicating that D. nepalensis may be parthenogenetic. A faster growth rate, and the production of more cocoons in cow compared with horse manure indicate that cow manure is a preferred source of food for D. nepalensis.     

孵化过程中鸡卵壳细微结构及四种元素含量变化的初探

用扫描电镜对孵化过程中鸡卵壳内表面结构及其变化进行了初步观察。在孵化第10～14天,卵壳内表面结构变化很大,蛋白纤维由粗、长变细、短,纤维网隙间的CaCO_3颗粒变小变少,渐渐消失。同时用等离子发射光谱分析技术测定、分析了卵壳内钙、镁、铁、锌四种元素在孵化期间的变化,发现占卵壳组成绝大部分的钙、镁变化趋势为减少,其中钙在孵化第18～21天时才发生大幅度减少。     

中国小麦条锈菌分子标记技术的研发与应用综述

概述了小麦条锈病早期定性、定量监测,介绍了小麦条锈菌种内特异性引物的设计及应用,主要包括小麦条锈菌生理小种的特异性标记开发和小麦条锈菌小种特异性引物的应用。     

催青温度对家蚕二化性品种滞育激素受体基因表达的影响及基因的结构特征

家蚕二化性品种的卵滞育与否受上代环境影响,25℃高温明催青将产滞育卵,而15℃低温暗催青将产非滞育卵。为探究催青温度调控二化性家蚕滞育的分子机制,对从家蚕卵巢细胞中克隆的家蚕滞育激素受体基因(Bmdhr)的5种cDNA进行生物信息学分析,结果表明Bmdhr基因的5种cDNA由相同的mRNA转录本通过不同的剪接方式而来,其中Bmdhr mR-NA-1与Bmdhr mRNA-2编码的氨基酸序列相同,Bmdhr mRNA-4编码的氨基酸序列与家蚕滞育激素BmDHR-1的序列相似度达99.2%。将家蚕二化性品种秋丰的蚕卵用蛾区半分法分成2组,分别以15℃暗催青和25℃明催青,利用实时荧光定量PCR分析催青温度对家蚕不同发育时期及蚕体组织中Bmdhr基因mRNA转录的影响。结果显示:Bmdhr mRNA-1主要在蛹期卵巢中表达,在对滞育激素最敏感的化蛹后4 d时,其转录水平急速上升至峰值,并且高温催青的转录水平高于低温催青;Bm-dhr mRNA-4主要在各发育时期的蚕体血液中表达,特别是在高温明催青条件下,其在蛹期血液中的转录水平是低温暗催青的7.7倍,说明BmDHR-4可能是决定家蚕二化性品种卵滞育与否的关键因子之一;Bmdhr mRNA-5在化蛹后2～3 d的卵巢中转录水平高,且低温催青的转录水平高于高温催青,化蛹后3 d其转录水平开始下降,至化蛹后4～5 d 2种催青处理间的转录水平无显著差异。研究结果为阐明家蚕滞育的分子机制积累了实验数据。     

孵化过程中种蛋内色氨酸-烟酸的关系研究

选30周龄Arbor Acre种母鸡80只,设5个处理。各处理为16只鸡,在饲喂相同基础日粮条件下,分别添加烟酸0、15、30、60和120mg/kg。试验期为12周。于试验结束前两周收集种蛋,进行孵化试验。 试验结果表明,随着日粮烟酸水平的提高,种蛋内烟酰胺含量依次递增。孵化后期种蛋内烟酰胺含量明显升高,出壳雏鸡体内烟酰胺含量比入孵种蛋高4-5倍。并发现增加的烟酰胺系由种蛋内色氨酸合成,而且这种转化似乎受到种蛋内烟酰胺含量的诱发,含量越高,诱发色氨酸转化为烟酰胺的效率越高。