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51.
52.
Norio Nishimura 《Journal of General Plant Pathology》2007,73(5):342-348
Selective media without pentachloronitrobenzene were developed for quantitative assays of Fusarium
oxysporum in soils. Media Fo-G1 and Fo-G2 were effective for naturally infested soils, Fo-W1 and Fo-W2 for wild-type isolates in soils
containing a nitrate-nonutilizing (nit) mutant, and Fo-N1 and Fo-N2 for nit mutants. Selective media were made using ammonium citrate dibasic, l-sorbose, econazole nitrate, 25% iminoctadine triacetate solution and 50% tolclofos-methyl wettable powder for soil dilutions
of 100-fold or more (Fo-G1, FoW1 and Fo-N1) and 10-fold (Fo-G2, Fo-W2 and Fo-N2). Potassium chlorate was added to Fo-N1 and
Fo-N2. The efficacy for selectively isolating F. oxysporum was confirmed using six soils naturally infested with one of six formae speciales of F. oxysporum and with soil dilutions containing conidia of wild-type strains or nit mutants from the six formae speciales. On Fo-G1 and Fo-G2, most colonies of F. oxysporum were compact and round with purplish or reddish pigment in the reverse. Cylindrocarpon sp. formed colonies as large as those of F. oxysporum but were distinguishable by their colony morphology. Other contaminants such as F. solani, F. moniliforme, and Trichoderma were suppressed by medium ingredients and colonies of F. oxysporum. On Fo-W1 and Fo-W2, colony morphology of F. oxysporum and contaminants corresponded to that on Fo-G1 and Fo-G2, although F. oxysporum failed to produce the pigment. On Fo-N1 and Fo-N2, nit mutants formed clear colonies from 100- and 10-fold soil dilutions, respectively, and contaminants seldom formed large colonies. 相似文献
53.
利用紫外光谱测定了云杉硫酸盐4-脱氧-4-己烯糖醛酸在甲酸钠中水解动力学。结果表明该水解反应为一反应速度较快的拟一级反应。此外,该水解反应的选择性较高,可望应用在无元素氯(ECF)和全无氯(TCF)漂白技术中。 相似文献
54.
不同强度的择伐作业对保留木与幼树幼苗的影响 总被引:7,自引:2,他引:7
采用标准地的方式调查不同强度的择伐作业前后常绿阔叶林林分中保留木和幼树幼苗的变化.结果表明:保留木的损伤与采伐木的胸径及择伐强度有关.胸径越大则损伤率越大.择伐强度亦然.择伐作业后幼树的破坏与择伐强度间无明显的关系.这与作业的具体情况有关.择伐后与皆伐未整地经一段时间.林内幼苗数量都有所增加,尤以皆伐作业和弱度择伐为最. 相似文献
55.
检查法第一经理期研究 总被引:16,自引:0,他引:16
检查法是一种适合于异龄林的集约经营方法。本文在我国首次进行检查法应用研究(1987-1992)的基础上,对择伐林分的径级分布、混交比例、蓄积结构、生长量、择伐强度等方面进行了系统分析,并比较了这些林分的蓄积生长量、经济效益等。应用该法不仅使蓄积生长量达到较高的水平,还充分发挥了森林的多种效益,使森林得以持续发展。与同样条件下的人工林皆伐方式相比具有一定的优越性。试验中改变了国外应用该法时的全林每木 相似文献
56.
We assessed seed fate of six tree species in a seasonally deciduous forest of Central Brazil. Seed germination, predation, removal and death caused by pathogens or dessication were followed in an undisturbed forest site, a logged forest site, and an active pasture. In both forest types we sowed seeds under patches of liana tangles (Low Forest habitat) and under patches of mature forest (High Forest habitat). Seeds were monitored weekly for up to 8 months. Overall, small-seeded species (Astronium fraxinifolium and Tabebuia impetiginosa) had high germination, although germination was lower in the pasture due to insect predation. The hard-coated seeds of Erythrina sp. had higher germination rates in the pasture. The large-seeded Cavanillesia arborea and Swartzia multijuga had high seed removal (ca. 90%) in the pasture and under High Forest, but only 23–34% under Low Forest in the logged site. Lower removal of large seeds in Low Forest suggests that this habitat conceals the seeds and constrains the movement of large mammals. Both species were favored in Low Forest, suggesting that caution should be used when managing lianas. When protected from predation, seeds with a soft coat and high water content, such as the seeds of Eugenia dysenterica and S. multijuga, died from desiccation in the pasture. Restoration efforts must take into consideration high mortality caused by desiccation or insect predation in abandoned pastures of dry forests. 相似文献
57.
长白山森林的采伐更新方式 总被引:5,自引:0,他引:5
This paper discussed the characteristics of degenerated forest ecosystems in Changbai Mountain area,which include over-harvest natural forest,typical secondary forest,derived forest,and artificial forest.Forest cutting and regeneration methods that were historically used in the region were summarized.They lnclude diameter-class selective cutting,clearcutting,upbringing selective cutting,and selective sutting.We proposed cutting methods for the broad-leaved Korean pine mixed forest,spruce-fir forest,and larch forest.The measures for restoring the original mixed forest ecosystems were recommended. 相似文献
58.
高产稳产优质耐旱型水稻新品种金穗1号的选育及栽培技术研究 总被引:1,自引:0,他引:1
金穗1号是以花培品种“早花2号”为亲本,与优良性状互补的品种杂交配组育成的水稻新品种。既保持了水稻品种高产稳产抗性强品质优的特点,而且抗旱性突出,适合旱直播栽培。冀东旱直播高产栽培的关键在于早播,充分利用当地的气候条件。 相似文献
59.
Nielsen MK 《Veterinary parasitology》2012,185(1):32-44
Clinically important equine parasites are ubiquitous in managed horse populations. The traditional approach to parasite control is frequent administration of anthelmintics to all horses on a farm. However, increasing levels of anthelmintic resistance is forcing horse owners and veterinarians to shift this control paradigm. Treatment regimens involving routine deworming of all horses throughout the year are now being replaced by more sustainable approaches, which take in to account the importance of maintaining adequate parasite refugia. The selective therapy principle has been recommended for more than 15 years, but there is limited experience with this approach. The relative magnitude of the faecal egg count for an individual horse is a consistent trait, and this provides a reliable basis for selective therapy. But no studies have evaluated the consequences of selective therapy in the long-term, and such studies are strongly needed to validate this approach. Importantly, it remains unclear how selective therapy may affect the prevalence and intensity of other parasites of significant pathogenic potential (e.g. Strongylus vulgaris), which have become uncommon due to years of intensive chemotherapy. Consequently, a selective approach requires vigilant surveillance of the parasite fauna and intensity. This places a demands for reliable diagnostic tools. Also noteworthy is the fact that the majority of equine nematode parasites are more pathogenic during their larval stages, when they cannot be detected by traditional egg counting techniques. Consequently, parasite-specific diagnostic tools capable of assessing prepatent parasite burdens, and able to differentiate between strongyle species of different pathogenic potentials, would be of great value to the equine clinician. Tools for detecting infections with the tapeworm Anoplocephala perfoliata are laborious, difficult to interpret, and at present there is no established method to evaluate treatment efficacy. Thus, better diagnostic tools are needed for tapeworms as well. Biological control, especially the predacious fungi have demonstrated good potential as an adjunct for strongyle control and such a product could easily have a market in equine establishments. In summary, there is general agreement that the traditional treat-all at frequent interval approach should be abandoned, and that optimal parasite control can be maintained with far fewer anthelmintic treatments. But better diagnostic techniques and more evidence documenting the long-term consequences of selective therapy programs are needed to develop and validate systems for sustainable equine parasite control. 相似文献
60.
本文以我国水产养殖主导品种吉富罗非鱼(farmed tilapia)为研究材料,进行扩增片段长度多态性(AFLP)反应体系的研究,初步建立了一套适合罗非鱼的AFLP反应体系。对体系中关键环节的优化结果如下:基因组DNA要求无降解和RNA污染,OD260/OD280比值在1.8~2.0之间;基因组DNA EcoRⅠ/MseⅠ37℃双酶切6h、20℃连接20h,连接产物10倍稀释,PCR预扩增产物稀释45倍作为选择性扩增的模板,选择性扩增产物经6%变性丙烯酰胺凝胶电泳检测可获得条带清晰、背景干扰小的图像。该体系的构建为今后进行罗非鱼群体遗传多样性分析、种质鉴定、重要经济性状分子标记的开发及遗传连锁图谱构建等方面研究提供了参考。 相似文献