土壤水分与氮素追施比率的关系

在黄淮豫东平原商丘试验区进行了三年冬小麦土壤水分与Ｎ素追施比率的关系田间试验。结果表明，冬小麦的土壤水分和追Ｎ比率间存在明显的互作效应，不同土壤水分条件要求与之相适宜的追Ｎ比率。在旱作条件下（冬小麦生育期降雨２００～２６０ｍｍ），适宜的追Ｎ比率为２５％或０（全部底施）；中等以上供水条件（全生育期浇水二次以上）以５０％的追Ｎ比率为宜。只有如此才能提高水分利用效率和肥料利用率，充分发挥水肥的效益     

不同追肥次数对烤烟生长发育的影响

【目的】施肥是烤烟栽培的关键技术之一,追肥量、追肥方法、追肥次数对烤烟的生长、发育、产量和品质都具有显著的影响;【方法】以K326为材料,研究了不同追肥次数对烤烟生长发育的影响;【结果】由本试验可知,分5次追肥的E处理的烟株生长发育状况优于其他处理和对照,说明E处理的追肥方法更有利于烟株的生长发育;【结论】五次分追的追肥方法效果最佳,此方法可用于农业生产。     

结合高接换种综合防治柑橘溃疡病

柑橘溃疡病是对柑橘生产威胁极大的重要细菌性病害，为国内外植物检疫对象，其病源为黄单孢杆菌属的一种细菌，即黄油菜单孢菌柑橘致病变种Xanthomonas campestris pv．citri（Hasse）Dye。该病危害柑橘枝梢、叶片及果实，导致树势衰退，产量降低，损毁果实外观。     

香蕉束顶病毒海南分离物DNA2编码区的克隆及抗血清的制备

利用PCR方法克隆香蕉束顶病毒海南分离物(Banana bunchy top virus,BBTV-HN)DNA2编码区,将其插入到原核表达载体pGEX-6p-1谷胱苷肽-S-转移酶(GST)基因下游.所得克隆pGEX-HN-B2测序结果表明,插入的DNA2片段为267 bp,且表达相位和理论上设计的完全一致.把此重组质粒转化到E.coli Rosetta(DE3)中,经过异丙硫代半乳糖苷(IPTG)诱导后出现约33 Ku融合蛋白质表达条带.为获得特异的血清,切下目的表达条带并免疫兔子.经Western-blotting检测,获取的血清可以和表达的33 Ku融合蛋白特异结合,表明已成功获得DNA2编码蛋白的血清.     

1年生银杏苗嫁接育苗对比试验初报

培育银杏嫁接苗，通常都采用2—3年生实生苗作砧木。我们通过秋、春两季试验，采用1年生实生苗作砧木，同时进行4种嫁接方法比较，其中顶芽劈接嫁接成活率达100%，平均高可达60．70cm，枝径1．04cm，而且苗木质量好。     

高海拔山区坡地杂交玉米品种(组合)高产栽培技术探讨

在高海拔山区缓坡地,选择不同杂交玉米品种(组合)进行栽培技术试验,结果表明,施氮方式对杂交玉米产量影响显著,平展型和半紧凑型玉米在追肥2次以上均能发挥增产潜力;半紧凑型新组合安2032在种植密度较高(4 000株/667m2)、追施3次氮肥的条件下,产量最高(701 kg/677 m2).安2032新组合对缓坡地有较强的适应性和丰产性.     

马铃薯茎尖脱毒与快繁技术应用研究进展

从马铃薯茎尖脱毒和脱毒快速繁殖2个方面叙述了当前马铃薯茎尖植物组织培养技术的研究现状及进展,具体分析了包括影响茎尖大小、外源激素、温度、湿度等环境因素以及不同基质养分成分等因素.指出了脱毒与快繁技术存在的主要问题,并展望了今后技术研究方向.     

不同疏剪技术对大粒菜用蚕豆产量和外观品质的影响

为提高菜用蚕豆产量和外观品质,对大粒菜用蚕豆进行摘心、疏枝、疏花和打顶等疏剪技术的应用试验。结果表明,大粒菜用蚕豆苗期摘心会减产6.56%,"疏枝 打顶"则可提高产量、改善青荚外观品质,产量比对照增10.66%,结合"摘心 疏枝 疏花 打顶"综合措施的应用,增产增收效果更显著,青荚产量提高33.67%,青荚成熟期集中,2粒以上荚(含2粒)比例增加,出口成品率增加2.5个百分点。     

香蕉束顶病毒株系生物学特性的研究

 在广东香蕉束顶病株症状基本相同的情况下,在8个产区分别随机采集11~15个标样共111个分离物,接种在香蕉苗上,其后又从8个产区的分离物中各选取1个代表分离物用于进行各项研究。寄主范围试验结果,这8个代表分离物可分为能侵染粉蕉的NSP株系(以广州天河分离物为代表的7个分离物)和不能侵染粉蕉的NS株系(高州代表分离物)。用Eco RI对8个毒源地的111个分离物DNA组分1进行酶切分析,结果表明:所有高州分离物共15个和信宜分离物14个中的9个都可以被酶切,应属NS株系;而其余6个毒源地的所有分离物及信宜分离物中的另外5个都不能被酶切,应属NSP株系。在病害潜育期方面,2个株系在大蕉上的差异达到显著水平;在香蕉4个品种上,2株系也存在较明显的差异,但其中有些差异未达到显著水平。在病毒增殖、运转速度及病毒达到高浓度所需的时间上,2个株系也存在显著的差异。     

The effect of initial concentration of carbofuran on the development and stability of its enhanced biodegradation in top‐soil and sub‐soil

Carbofuran was incubated in top‐soil and sub‐soil samples from a pesticide‐free site at a range of initial concentrations from 0.1 to 10 mg kg⁻¹. Amounts of the incubated soils were removed at intervals over the subsequent 12 months, and the rate of degradation of a second carbofuran dose at 10 mg kg⁻¹ was assessed. An applied concentration as low as 0.1 mg kg⁻¹ to top‐soil resulted in more rapid degradation of the fresh addition of carbofuran for at least 12 months. The degree of enhancement was generally more pronounced with the higher initial concentrations. When the same study was conducted in sub‐soil samples from the same site, an initial dose of carbofuran at 0.1 mg kg⁻¹ resulted in only small increases in rates of degradation of a second carbofuran dose. However, degradation rates in the sub‐soil samples were, in many instances, considerably greater than in the corresponding top‐soil samples, irrespective of pre‐treatment concentration or pre‐incubation period. Initial doses of 0.5 mg kg⁻¹ and higher applied to sub‐soil successfully activated the sub‐soil microflora. Application of the VARLEACH model to simulate carbofuran movement through the soil profile indicated that approximately 0.01 mg kg⁻¹ of carbofuran may reach a depth of 70 cm 400 days after a standard field application. The results therefore imply that adaptation of the sub‐soil microflora (c 1 m depth) by normal field rate applications of carbofuran is unlikely to occur. In experiments to investigate this in soils exposed to carbofuran in the field, there was no apparent relationship between top‐soil exposure and degradation rates in the corresponding sub‐soils. The results further confirmed that some sub‐soil samples have an inherent capacity for rapid biodegradation of carbofuran. The high levels of variability observed between replicates in some of the sub‐soil samples were attributed to the uneven distribution of a low population of carbofuran‐degrading micro‐organisms in sub‐surface soil. There was no apparent relationship between soil microbial biomass and degradation rates within or between top‐soil and sub‐soil samples. © 2001 Society of Chemical Industry