不同施钾处理对高产小麦地上部和土壤中钾素积累动态的影响

采用大田试验和室内分析的方法研究了不同施钾处理下高产小麦生育期间植株地上部钾素积累特点和土壤中钾素动态变化特点。结果表明,在小麦生育期间,钾素积累总体趋势是:前期积累缓慢上升,中期达到高峰,后期又有所下降,不同施钾水平下对钾素积累又有所不同。土壤中速效钾和缓效钾在小麦整个生育期间,在不同施钾处理下,由于受施肥、作物吸收、温度、降水及土壤水分运动的影响变化动态比较复杂。具体表现为:在不同施钾处理下,土壤中的速效钾和缓效钾在小麦生长的整个过程中,总是以K3保持最高水平,K2次之,K1最少。     

热带人工草地群落结构研究初探

研究4年生热带人工草地放牧与不放牧对群落结构的影响,结果表明:以热研2号柱花草和珊状臂形草为优势草种的人工草地,其中对照区(不放牧)干草产量8096kg/hm²,极显著高于天然草地116.04%,放牧区6324.5kg/hm²,显著高于天然草地68.77%;其产草量呈动态变化,以10月最高;植被群落呈垂直空间层状分布,产草量多集中在11～40cm草层;在放牧区热研2号柱花草的频度和产草量减少,珊状臂形草和有钩柱花草增加,草种分布均匀,结构合理,向进展方向演替。     

基于嵌入式OS的包装机械运动控制器设计方法

采用FLUENT软件模拟了伞罩除尘器内黑烟颗粒浓度的分布特性.在气相和颗粒相分别选用雷诺应力模型(RSM)和离散相模型(DPM)的基础上,计算了入口含尘质量浓度(1~7 g/m3)、入口气速(10~16 m/s)和黑烟颗粒粒径(0.24~11 μm)对伞罩除尘器内黑烟颗粒浓度的轴向和径向分布的影响.模拟结果表明:黑烟颗粒在伞罩除尘器内部的浓度分布在径向上可分为中间低浓度区和近壁高浓度区,而同一径向截面位置的黑烟颗粒浓度随着入口含尘质量浓度的增大而增大,随入口气速、颗粒粒径的增大而减小.将模拟结果与实验结果进行比较,发现模拟的压降值与实验值吻合较好,相对误差小于6%.这些研究结果将为建立完善的伞罩除尘器模型提供依据.     

15种热带乔灌木单宁含量动态分析

通过对15种热带乔灌木不同月份(2009年3月至2010年2月)单宁含量的测定,以期明确部分木本饲用植物单宁含量及其动态变化趋势。结果表明:15种热带乔灌木单宁平均含量由低到高顺序如下:对叶榕(Semen cuscuta L.f.)(0.39%)<刺桐(Erythrina variegata Linn.)(0.77%)<克拉豆(Cratylia argentea(Desv.)Kuntze)(0.78%)<假木豆(Dendrolobium triangulare(Retz.)Schindl.)(1.16%)<木豆(Cajanus cajan(Linn.)Huth)(1.29%)<双荚决明(Senna bicapsularis(Linn.)Roxb.)(1.38%)<破布叶(Microcos paniculata Linn.)(1.56%)<圆叶舞草(Codariocalyx gyroides(Roxb.ex Link)Hassk.)(1.57%)<大果榕(Ficus auriculata Lour.)(1.62%)<长穗决明(Senna didymobotrya(Fresen.)H.S.Irwin et Barneby)(1.82%)<大叶千斤拔(Flemingia macrophylla(Willd.)Prain)(1.91%)<黄牛木(Cratoxylum cochinchinense(Lour.)Blume)(2.14%)<银合欢(Leucaena leucocephala(Lam.)de Wit)(2.34%)<金合欢(Acacia farnesiana(Linn.)Willd.)(2.67%)<白饭树(Flueggea virosa(Roxb.ex Willd.)Voigt)(2.80%);15种热带乔灌木单宁含量差异较大且含量随月份变化明显。不同植物种类、生长时期、生长环境等可能是导致单宁含量差异的原因。     

云南省烟草青枯病的侵染动态

为了指导烟草青枯病的测报和防治,采用定期挖根调查采样和ELISA检测方法,对云南省烟草青枯病的侵染动态进行了研究。移栽后每周挖根调查结果和根、茎部样品的检测结果表明,在文山州青枯病重病田块,移栽后第5周根部样品首先检测出青枯雷尔氏菌（Ralstonia solanacearum,简称青枯菌）阳性,个别烟株根部出现黑色坏死症状;移栽后第7周根部样品青枯菌检出率达到50%左右、根部黑色坏死发病率开始快速上升,茎部无明显症状;移栽后第9周,根部发病率达到50%左右、个别烟株茎部出现黑色坏死症状。移栽后第12周,茎部青枯菌检出率、根发病率和茎部发病率均达到80%以上。根部样品青枯菌检出阳性、烟株根部显症、烟株茎部显症表现出一定的时间顺序（先后间隔约21d）。根青枯菌检出阳性时期和根黑色坏死的始发期可作为确定第一次施药时期的依据。对ELISA检测的验证试验结果表明,ELISA检测为青枯菌阳性的样品,可分离到典型青枯菌菌落,分离物ELISA检测同样为青枯菌阳性。     

不同施钾处理对高产小麦地上部和土壤中钾素积累动态的影响

464000河南省信阳市农专路1号信阳农业高等专科学校农业科学系     

Dynamics of dissolved and extractable organic nitrogen upon soil amendment with crop residues

Dissolved organic nitrogen (DON) is increasingly recognized as a pivotal pool in the soil nitrogen (N) cycle. Numerous devices and sampling procedures have been used to estimate its size, varying from in situ collection of soil solution to extraction of dried soil with salt solutions. Extractable organic N (EON) not only consists of DON but contains also compounds released from soil biomass and desorbed organic matter. There is no consensus whether DON or EON primarily regulates N mineralisation in soil, and their contribution to N mineralisation has not been quantified simultaneously. We evaluated three sampling procedures on their ability to determine the dynamic of dissolved organic N pools. The three procedures were the determination of DON in 1) soil solution collected by centrifugation, and the determination of EON in 2) a 0.01 M CaCl₂ extract of field moist or 3) dried soil. We added unlabeled leek and ¹⁵N-labeled ryegrass residues to a loamy sandy soil to create a temporarily increase in DON and EON, to stimulate microbial activity, and to test whether the source and dynamics of the three pools differ. We also tested whether the flow of N through DON or EON was associated with the production of inorganic N using ¹⁵N isotope tracing. Sampling procedures significantly affected the amount, but not the dynamics and origin of the three organic N pools. DON and EON (determined on field-moist and dried soils) showed all a significant increase upon crop amendment and returned to their background concentrations within 10 to 30 days. The fraction of DON and EON originating from the crop residue slightly decreased over 138 days and was not different for DON and EON. Field moist extraction of a loamy sandy soil with 0.01 M CaCl₂ gave a reliable estimate of the concentration of in situ dissolved organic N. In contrast, extraction of dried soil significantly increased EON compared to DON. The agreement in dynamics, ¹⁵N enrichment and C-to-N ratio’s indicate that dissolved and extracted organic N have a similar role in N mineralisation. Our results also suggest that they make a minor contribution to N mineralisation; changes in the turnover rate of EON were not associated with changes in the net N mineralisation rate.     

甘蓝型春油菜对磷素吸收的动态研究

[目的]探讨青海省东部农业区油莱主产区甘蓝型春油莱对磷素吸收的变化规律。[方法1采用完全随机区组设计在互助县台予乡进行不同施肥处理对春油莱磷素吸收的动态研究。[结果1油莱从苗期到成熟期其根系和茎秆全磷含量均表现为下降的趋势,而叶片中全磷含量变幅较小。对籽粒、茎秆、角壳和根系中全氮、全磷、全钾含量进行测定,籽粒中含量均高于茎秆、角壳和根系中全氮、全磷、全钾含量,且含量全钾〉全氮〉全磷．．苗期土壤中的速效磷含量在整个生育期中最高,随着生育进程的推进,土壤中的速效磷均呈下降趋势。OPT＋1／2P处理和推荐施肥OPT处理的速效磷含量均高于OPT-P、OPT-1／2P和OPT-1／4P.[结论]为青海省油菜主产区合理使用磷肥,提高磷肥利用率提供了参考依据、     

基于系统动力学的水污染问题研究

基于系统科学的思想,从人口、经济与环境相互耦合的视角,构建水污染问题的系统动力学模型。结合应用统计模型、计量经济模型,来确定系统动力学模型的相关参数,再以vensim软件为仿真平台,对水污染问题进行仿真研究。最后以南京市为例,对1995～2020年南京市水污染问题仿真。结果表明,1995～2015年南京市水污染量持续增加,之后水污染量在稳定中稍有下降趋势。水污染导致的环境成本逐年增加,传统的GDP核算体系在未来显然是不合适的,南京市应尽快完善实施绿色GDP核算体系。     

吉林省稻瘟病菌生理小种的分布与消长动态

2002～2007年在吉林省内各稻作区采集732份稻瘟病标样,分离出568个有效单孢菌株,用7个中国稻瘟病菌鉴别品种鉴定为7群39个小种,优势种群为ZE群和ZG群,其次是ZD群和ZF群;优势小种为ZE1和ZG1,其次是ZF1和ZD1。鉴定结果表明:吉林省稻瘟病菌生理小种以粳型小种为主,而且粳型优势小种在不同年份、不同地区有变化。