Micro-scale heterogeneity in urban forest soils affects fine root foraging by ornamental seedlings of Buddhist pine and Northeast yew

Urban soils are frequently characterized by a strong heterogeneity caused by intense anthropogenic activity and land use changes. Soil heterogeneity is commonly known to affect tree root development, but little has been detected concerning root foraging by ornamental trees in heterogeneous urban soils at micro-scale. In this study, Buddhist pine [Podocarpus macrophyllus (Thunb.) D. Don] and Northeast yew (Taxus cuspidata S. et Z.) were selected as ornamental tree species for a two-year study. In the first-year, seedlings were cultured under contrasting photoperiods to generate different morphologies. In the second year, seedlings were transplanted to pots filled with soils collected from an urban forest. Controlled-release fertilizers (N-P₂O₅-K₂O, 14-13-13) were evenly broadcasted to a half patch of the pot (heterogeneity) or to both halves (homogeneity) on the surface 5 cm beneath the pot-top at the rate of 0.135 g N seedling⁻¹. In the fertilized heterogeneous patch, larger Buddhist pine seedlings had greater dry weight, length, surface area, volume, number of tips, and morphological foraging-precision in fine roots. Compared to Northeast yew seedlings under natural photoperiod in the first year, those under the extended photoperiod had larger size, greater fine root biomass, and length but lower foraging-precision in the second year. N and P concentrations in second-year fine roots mainly increased with the availability of patches generated by fertilization for both species. In conclusion, the ability to forage for nutrients by ornamental tree seedlings in heterogeneous urban forest soils was species-specific. Buddhist pine seedlings had higher foraging precision in heterogeneous urban soils than Northeast yew seedlings due to their response to the extended photoperiod during culture.     

菊粉的原生素作用研究进展

本文综述了菊粉的原生素作用及机理 ,主要包括菊粉的微生物发酵、营养、免疫和抗癌作用等。     

不同覆盖方式下的西瓜地养分对比研究

对不同覆盖方式下的西瓜地土壤养分进行了对比研究。结果表明:地面增加覆盖物后可以减轻耕层的含盐量使盐分由上层转移到下层,而灌水能使土壤容重增加,其中抑盐效果最好的是地膜覆盖,其次是砂田+地膜覆盖、砂石覆盖次之;在无灌溉水的条件下,养分利用率依次是砂石+地膜覆盖砂石覆盖地膜覆盖,并且0～20cm和20～40cm土层土壤碱解氮和全氮含量最高的覆盖方式是地膜覆盖,最低的是砂石+地膜覆盖。因此,在干旱地区推广发展砂石+地膜覆盖并适当增施肥料,有助于增产增收,保持干旱地区农业的持续发展。     

苜蓿干草捆贮藏过程中的营养物质含量动态变化研究

为探讨苜蓿干草捆贮藏过程中营养物质含量的动态变化规律,对含水量为15%、打捆密度为150kg/m3的苜蓿草捆在不同贮藏时间(1、10、30、90、180、360d)营养物质含量和相对饲喂价值(RFV)的动态变化情况进行研究。结果表明,在整个贮藏过程中,苜蓿干草的粗蛋白(CP)含量总体呈下降趋势,与贮藏1d时相比,不同贮藏时间段苜蓿干草的CP含量均显著下降(P<0.05);从CP含量角度评价,苜蓿干草等级由1级下降到2级。苜蓿干草的中性洗涤纤维(NDF)含量随贮藏时间的延长而增加,贮藏360d时的NDF含量显著高于贮藏时间在90d之内的NDF含量(P<0.05);从NDF含量角度评价,苜蓿干草等级由2级下降到3级。酸性洗涤纤维(ADF)含量也随贮藏时间的延长而增加,贮藏10d之后ADF含量开始显著增加(P<0.05);从ADF含量角度评价,苜蓿干草等级由1级下降到4级。贮藏时间在30d以上的苜蓿干草DMI值显著低于贮藏时间在30d之内的DMI值(P<0.05);从DMI值角度评价,苜蓿干草等级由1级下降到3级。贮藏时间在90d以上的苜蓿干草DDM值显著低于贮藏时间在90d之内的DDM值(P<0.05);从DDM值角度评价,苜蓿干草等级由1级下降到4级。随着贮藏时间的延长,苜蓿干草的RFV值显著降低(P<0.05),且在贮藏180~360d的时间段内,RFV值下降幅度较大;从RFV值角度评价,苜蓿干草等级由2级下降到3级。综合比较,苜蓿干草在贮藏180d之后营养价值大幅度下降,因此,在贮藏180d之内出售或者饲喂家畜比较适合。     

Evaluating environmental impacts of the Japanese beef cow–calf system by the life cycle assessment method

The objectives of this study were to evaluate the environmental impacts of a beef cow–calf system using a life cycle assessment (LCA) method and to investigate the effects of scenarios to reduce environmental impacts on the LCA results. The functional unit was defined as one marketed beef calf, and the processes associated with the cow–calf life cycle, such as feed production, feed transport, animal management, the biological activity of the animal and the treatment of cattle waste were included in the system boundary. The present results showed that the total contributions of one beef calf throughout its life cycle to global warming, acidification, eutrophication and energy consumption were 4550 kg of CO₂ equivalents, 40.1 kg of SO₂ equivalents, 7.0 kg of phosphate (PO₄) equivalents and 16.1 GJ, respectively. The contribution of each process to the total environmental impact in each environmental impact category showed a similar tendency to the contribution of each process in each environmental category reported in the case of the beef fattening system as a whole. The results from this analysis showed that shortening calving intervals by 1 month reduced environmental impacts by 5.7–5.8% in all the environmental impact categories examined in the current study, and increasing the number of calves per cow also reduced environmental impacts in all the categories, although the effects were smaller.     

我国主要蔬菜的养分吸收和需求特征

研究我国主要蔬菜养分需求对建立蔬菜推荐施肥新方法至关重要.本文采用文献检索和实地调查采样、测定相结合的方法,依据QUEFTS模型分析了露地白菜、露地萝卜、设施番茄和露地大葱产量与养分吸收之间的关系,获得养分吸收最佳曲线,估算单位蔬菜产量的养分最佳需求量.结果表明,4种蔬菜的产量、养分吸收量和养分内效率(IE)变异很大....     

通过调配培养基优化葡萄试管苗的培养质量

通过分析田间植株营养成分调配了葡萄的生根培养基H配方.比较了H,1/2 MS,以及1/2B53种培养基对试管苗的培养效果.一元方差分析表明,H和1/2 MS生根率显著大于1/2B5配方,H配方的株高和比叶面积显著高于另外2种配方.主成分分析表明,H的综合培养状况优于另外2种培养基.总结认为,基于植株营养成分分析进行培养基优化的方法可以在藤本植物上得到运用,主成分分析方法在评价试管苗综合生长状况上有独特的优势.     

牦牛发情周期中卵巢卵泡发育状况的组织学观察

运用组织学技术对36头处于发情周期的健康成年母牦牛卵巢卵泡的结构与发育状况进行了观察。结果表明，牦牛发情周期中卵巢卵泡发育的组织结构与其他牛基本相似。每对卵巢中原始卵泡数和生长卵泡数在发情前期、发情期、发情后期和发情间期之间差异不显著（P〉0．05）；发情前期的囊状卵泡数与发情期、发情后期和发情间期之间差异不显著（P〉0．05），发情期和发情后期均与发情间期差异显著（P〈0．05）。闭锁生长卵泡数在4个时期之间差异不显著（P〉0．05）；发情期的闭锁囊状卵泡数与其他3期之间差异极显著（P〈0．01），发情前期和发情间期均与发情后期差异显著（P〈0．05）。各级卵泡的闭锁形式各有特点。在生长卵泡、囊状卵泡及相应闭锁卵泡的卵泡膜中均见到了胶原纤维和网状纤维。     

甘肃高山细毛羊妊娠母羊营养需要量估测

借助其他品种绵羊营养需要的一些研究方法,结合甘肃高山细毛羊四季牧草干物质采食量、营养物质摄入量、采食牧草营养成分、牧草营养物质消化率以及生产相关数据,采用析因法估测甘肃高山细毛羊能量和蛋白质需要量:成年母羊维持代谢能需要量为6.58 MJ/d(每kg代谢体重维持代谢能需要为0.417 MJ/W^0.75),维持蛋白质需要量107.62 g/d;妊娠前期代谢能需要量为12.54 MJ/d,粗蛋白质需要量125.19 g/d;妊娠后期代谢能需要量为12.86 MJ/d,粗蛋白质需要量为146 g/d;通过对比研究表明,甘肃高山细毛羊成年母羊钙需要量约为8.22~9.61 g/d,磷需要量为4.98~5.87 g/d,食盐需要量为9~16 g/d。     

二甲基二硫的生物活性评价及对土壤养分的影响

采用室内生物活性测定方法,评价二甲基二硫(dimethyl disulfide,DMDS)对土壤病原线虫和土传病原菌的毒力,比较不同浓度药剂处理对土壤理化性质和土壤呼吸的影响,为探究DMDS作为新型土壤熏蒸剂提供切实可行性的依据。结果表明:DMDS熏蒸对土传病原线虫和镰刀菌属的LD_(50)分别为4.743 mg/kg和1.513 mg/kg,可见DMDS对病原线虫和镰刀菌有良好的生物活性。对土壤理化性质进行数据分析发现:DMDS能显著增加土壤铵态氮含量,抑制硝化作用过程,减少NO~-_3-N的产生,提高植物可吸收态氮素水平。DMDS处理的土壤有机质含量和电导率均显著高于对照土壤,而土壤pH和速效钾含量较对照均有降低。此外,熏蒸土壤中有效磷含量较对照减少,但两者无显著差异。对DMDS熏蒸后土壤进行底物诱导呼吸试验,表明DMDS能够在试验初期抑制土壤微生物生物量。本试验结果可为指导DMDS的科学使用提供理论依据及对土壤微生物活性的影响作出科学评价。