黄瓜单体异附加系的筛选与观察   总被引：9，自引：0，他引：9  

陈劲枫  罗向东  钱春桃  曹清河 《园艺学报》2003,30(6):725-727

 将甜瓜属异源三倍体与栽培黄瓜‘北京截头’杂交，经胚胎拯救获得了两个2n=15 (14C+1H)的单体异附加系，编号分别为02—17和02—39。02一l7植株叶形为戟形，02—39为深陷的掌状形，并且果刺均为白色，不同于异源三倍体的掌状心脏形和黑刺，果形比异源三倍体黄瓜长而更接近普通黄瓜。细胞学研究发现，单体异附加系在终变期和中期I染色体构型主要是由7个二价体和1个单价体构成，出现三价体的频率为4％ ～5％ ，中期Ⅱ不均等分裂形成不同的两极，一极染色体为8条，另一极为7条。RAPD分析证明它们分刖附加了野生种Cucum／s hystrix的染色体。  相似文献   

外源氮添加对湿地土壤N_2O排放量的影响     

史昊先  高晓霞  于景丽  赵吉 《农业环境与发展》2014,(5)

为搞清湿地土壤驱动N2O排放的关键氮源类型,有效减少湿地N2O的排放,本文通过室内控制温湿度,用气相色谱法分析不同外源氮素对湿地N2O排放的影响。结果表明:外加氮源组总是高于对照组N2O排放量(4.4 mg·m-3)。在设定的剂量范围内,单独添加尿素或尿素与硝酸铵1∶1配合时N2O排放量呈现先增后减的单峰分布趋势,峰值分别为10.6 mg·m-3和229.0 mg·m-3;单独添加硝酸铵时N2O排放量(32.6~111.0 mg·m-3)随着氮素添加量增加呈现持续上升趋势。单独添加尿素或硝酸铵、尿素与硝酸铵1∶1配合均促进N2O的排放,但硝酸铵尿素混合添加对N2O排放量的贡献单独添加硝酸铵单独添加尿素。这为预测内蒙古高原区农牧交错带湿地氮素输入可能带来的温室效应和有效减排提供科学依据。  相似文献   

氮添加对天山高寒草原土壤酶活性和酶化学计量特征的影响   总被引：1，自引：0，他引：1  

勒佳佳  苏原  彭庆文  耿凤展  韩文轩  李文利  李凯辉  刘学军 《干旱区研究》2020,(2):382-389

为探究氮添加对高寒草原生态系统土壤酶活性的影响,于2018年在中国科学院巴音布鲁克草原生态系统研究站,选择4个氮添加水平(对照,N0,0 kg·hm^-2·a^-1;低氮,N1,10 kg·hm^-2·a^-1;中氮,N3,30 kg·hm^-2·a^-1;高氮,N9,90 kg·hm^-2·a^-1),开展土壤酶活性对氮添加响应的研究,分析土壤酶活性对氮添加的响应特点,土壤酶化学计量比以及土壤酶活性与土壤环境因子的关系。结果表明:与对照相比,氮添加在N3水平显著增加β-1,4葡萄糖苷酶(βG)、β-D-纤维二糖水解酶(CBH)和β-1,4木糖苷酶(βX)酶活性(P<0.05),N1和N3水平显著增加碱性磷酸酶(AKP)活性(P<0.05),N3水平显著降低多酚氧化酶(PPO)活性(P<0.05),氮添加对亮氨酸氨基肽酶(LAP)活性影响不显著,N3水平下显著增加N-乙酰-β-D氨基葡萄糖苷酶(NAG)活性(P<0.05)。相关分析表明,8种土壤酶活性均与土壤有机碳(SOC、NAG除外)和总磷(TP)显著相关,与土壤总氮(TN)不相关。研究区土壤酶活性C∶N∶P化学计量比为1∶1∶1.2,与全球生态系统的土壤酶活性C∶N∶P的比值1∶1∶1相偏离,表明该研究区土壤微生物生长受磷素限制。冗余分析(RDA)进一步揭示出土壤有机碳和土壤全磷含量是影响土壤酶活性的主要因子。  相似文献   

兽药中非法添加物检测及风险防范技术研究     

顾进华  张秀英  汪霞  范强  于晓辉  韩宁宁  赵晖  龚旭昊  高光 《中国兽药杂志》2021,55(9):71-77

本文总结了近年来兽药中非法添加的规律,分析成因;全面梳理现有检测标准,对非法添加物检测方法的检测对象和目标药物进行统计分析,研究检测方法发展及内在联系。在非法添加物检测方法提升和风险防范方面进行思考,提出筛查与确证方法并重、进一步扩大检测方法适用性、加强高效、高通量检测技术研究、拓展非法添加物检测品种范围;加强检查与宣传、疏堵结合,全面减少非法添加风险。  相似文献   

放牧和氮添加对半干旱沙质草地优势种糙隐子草及群落功能性状的影响   总被引：1，自引：0，他引：1  

孙一梅  田青  郭爱霞  张森溪  吕朋  左小安 《草地学报》2021,29(3):563-571

为探究氮沉降背景下放牧对半干旱沙质草地植物功能性状的影响,本试验探究了放牧和短期氮添加(20 g·m^-2·a^-1)对半干旱沙质草地优势种糙隐子草(Cleistogenes squarrosa)和群落功能性状的影响。结果表明：放牧和氮添加增加了糙隐子草的重要值,放牧降低了糙隐子草叶面积,氮添加显著降低了围封草地中糙隐子草叶干物质含量,增加了围封和放牧草地中糙隐子草叶氮含量(P<0.05);相同氮素水平下放牧降低了植物群落高度,氮添加增加了围封样地植物叶面积和叶氮含量,增加了放牧样地植物比叶面积和叶氮含量,降低了叶干物质含量(P<0.05);回归分析表明,糙隐子草叶面积和叶氮含量能较好地解释群落水平植物叶面积和叶氮含量的变化。半干旱沙质草地植物群落通过改变植株大小和主要叶性状来响应放牧和氮沉降,对预测未来草地生态系统结构与功能具有重要意义。  相似文献   

Nutrient addition and disturbance effects on the community composition and assembly in a desert steppe北大核心CSCD     

Qiao J.  Zuo X.  Yue P.  Wang G.  Wang J.  Wang Z. 《干旱区研究》2023,(6):958-970

The effects of short-term nutrient additions (NPKμ, 10 g·m- 2) and disturbances on the species diversity, functional traits, soil properties, and community assembly mechanisms of the herbaceous community in the Urat desert steppe were examined. A mixed linear model, principal component analysis, and null model methods were utilized and both disturbance and interaction treatments were found to significantly reduce species richness and β diversity. Short-term nutrient additions significantly reduced soil pH but increased soil electrical conductivity. Six functional traits of the dominant species (i.e. Stipa glareosa, Peganum harmala, Salsola collina, Corispermum mongolicum) and six community-weighted mean significant changes under the disturbance and nutrient addition treatments were identified. The disturbance and nutrient additions promoted the transformation of the dominant species in the community from conservative strategies to acquisitive strategies. The results of the two null models revealed that community assembly under the control tended to be a stochastic process, while the disturbance and interaction treatments tended to be deterministic processes, and that of the nutrient addition treatments tended to be weaker deterministic processes. Plant communities in the desert steppe responded and adapted to the nutrient additions and disturbances through changes in the dominant species and their crucial functional traits. © 2023 Chinese Academy of Sciences. All rights reserved.  相似文献   

多梯度氮磷添加对高寒草甸植物群落生物量与氮磷含量的影响     

刘艳  陈梦娇  郭童童  崔靖  李兰平  梁德飞  李永慧  张振华  朱小雪  任飞 《草地学报》2023,31(3):751-759

为研究不同梯度氮、磷单独及混合添加对高寒草甸植物群落生物量、植物养分含量及化学计量比的影响,本实验分析了青海省门源县典型高寒草甸植物群落地上总生物量,功能群水平地上生物量,植物全氮、全磷含量及氮磷比对多梯度氮、磷添加的响应情况。结果表明：氮、磷添加均对群落地上生物量影响极显著(P<0.001);氮添加对禾草类和豆科生物量影响极显著(P<0.001);磷添加对禾草类和莎草类生物量影响极显著(P<0.001);氮磷交互作用对豆科和莎草类生物量影响显著(P<0.05)。群落水平上,氮添加显著提高了植物全氮含量,对植物氮磷比(N∶P)有正效应,磷添加显著提高了植物全磷含量,对植物N∶P有负效应,植物全磷对N∶P的负效应大于全氮对N∶P的正效应。本研究表明氮、磷添加可能会使高寒草甸植物群落组成和植物养分含量发生改变,植物群落逐渐向禾草类发展;此外,高寒草甸植物生长趋向于受氮磷共同限制。  相似文献   

Impact of inorganic nitrogen additions on microbes in biological soil crusts     

《Soil biology & biochemistry》2015

Many studies have shown that changes in nitrogen (N) availability affect the diversity and composition of soil microbial community in a variety of terrestrial systems, but less is known about the responses of microbes specific to biological soil crusts (BSCs) to increasing N additions. After seven years of field experiment, the bacterial diversity in lichen-dominated crusts decreased linearly with increasing inorganic N additions (ambient N deposition; low N addition, 3.5 g N m⁻² y⁻¹; medium N addition, 7.0 g N m⁻² y⁻¹; high N addition, 14.0 g N m⁻² y⁻¹), whereas the fungal diversity exhibited a distinctive pattern, with the low N-added crust containing a higher diversity than the other crusts. Pyrosequencing data revealed that the bacterial community shifted to more Cyanobacteria with modest N additions (low N and medium N) and to more Actinobacteria and Proteobacteria and much less Cyanobacteria with excess N addition (high N). Our results suggest that soil pH, together with soil organic carbon (C), structures the bacterial communities with N additions. Among the fungal communities, the relative abundance of Ascomycota increased with modest N but decreased with excess N. However, increasing N additions favored Basidiomycota, which may be ascribed to increases in substrate availability with low lignin and high cellulose contents under elevated N conditions. Bacteria/fungi ratios were higher in the N-added samples than in the control, suggesting that the bacterial biomass tends to dominate over that of fungi in lichen-dominated crusts after N additions, which is especially evident in the excess N condition. Because bacteria and fungi are important components and important decomposers in BSCs, the alterations of the bacterial and fungal communities may have implications in the formation and persistence of BSCs and the cycling and storage of C in desert ecosystems.  相似文献   

Controllability of Phosphorus Losses in Surface Runoff from Sloping Farmland Treated by Agricultural Practices     

《Land Degradation \u0026amp; Development》2017,28(5):1704-1716

Phosphorus (P) loss from arable sloping land due to water erosion causes off‐site environment pollution in the Three Gorges area in China. This study aims to estimate the effects of agricultural practices on the reduction of P losses during water erosion processes under natural precipitation conditions: contour culturing with organic matter addition (CT + OM), contour culturing with wheat straw mulching (CT + SM), contour culturing with straw mulching and organic matter addition (CT + OM + SM) and conventional downslope culturing framework as a control (CK). Results demonstrated that CT + OM + SM could viably diminish runoff, sediment yields and P losses from arable sloping land. Compared with CK, CT + OM, CT + SM and CT + OM + SM lessened the surface runoff depths by 19%, 34% and 50%, respectively. A high curve number value induced a notable runoff potential from the plot. The surface‐runoff‐related total P (TP) loads for CK with yearly measures of 1·56 kg ha⁻¹ were significantly higher than those for CT + OM, CT + SM and CT + OM + SM at 1·07, 0·77 and 0·51 kg ha⁻¹ (p  < 0·05), respectively. With all things considered, the particulate P losses represented a significant division of TP losses, adding up to almost 80% in 2014 and 79% in 2015. The outcomes demonstrated that surface protection and organic matter addition are two of the greatest agricultural protection practices that lessen P losses in the surface runoff from sloping farmland by water erosion. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Development of buffer methods and evaluation of pedotransfer functions to estimate pH buffer capacity of highly weathered soils     

M. T. F. Wong  M. J. Webb  K. Wittwer 《Soil Use and Management》2013,29(1):30-38

The pH buffer capacity of a soil (pHBC) determines the amount of lime required to raise the pH of the soil layer from its initial acid condition to an optimal pH for plant growth and the time available under current net acid addition rate (NAAR) until the soil layer acidifies to a critical pH leading to likely production losses. Accurate values of pHBC can also be used to calculate NAAR from observed changes in soil pH. In spite of its importance, there is a critical shortage of pHBC data, likely due to the long period of time needed for its direct measurement. This work aimed to develop quick, simple and reliable methods of pHBC measurement and to test these methods against a slow (7‐day) titration used as benchmark. The method developed here calculates pHBC directly from the pH buffer capacity of the buffer solution and the increase in soil pH and corresponding decrease in pH of the buffer solution following mixing and equilibration. The pHBC values calculated using Adams and Evans or modified Woodruff buffers were in accord with those measured by slow titration. Buffer methods are easily deployed in commercial and research laboratories as well as in the field. The advantage of using buffer solutions to calculate pHBC instead of lime requirement is the broad application of this soil property. The pHBC of a soil is an intrinsic property that would not be expected to need remeasurement over periods of less than decades. Recurring lime requirement can be calculated from the soil's pHBC, initial and target pH values. A large proportion of the variability in pHBC was explained by the soil organic carbon content. This relationship between pHBC and soil organic carbon content allowed us to develop local pedotransfer functions to estimate pHBC for different regions of Australia.  相似文献