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991.
饲粮蛋白能量比值与产蛋鸡脂肪肝综合症发生率的关系研究 总被引:5,自引:1,他引:5
采用每千克含2.59、2.64、2.70及2.75兆卡的4个代谢能水平的配方,饲喂产蛋鸡,结果证明,日粮蛋白质与代谢能之间的比值大小,对鸡的生产性能和鸡脂肪肝综合症的发生率影响较大。试验1~4组蛋能比值依次为66.94、64.77、62.74及60.97,脂肪肝综合症的发生率相应为30%、 10%、 10%和0,其相关性极为显著(r=0.79);产蛋性能:第二组产蛋量最高(平均每羽16.49千克),第一组次之,第四组最低(15.36千克)。 相似文献
992.
对悬浮离心法回收昆虫病原线虫方法的改进 总被引:3,自引:0,他引:3
本文对Sanuders的悬浮离心回收线虫法进行了改进研究。保留第1次离心后上清液中含有的线虫,结果使小卷蛾线虫的平均回收率由32.2%上升到60.2%;离心处理对线虫的存活率及其对害虫的侵染率没有显著影响,但鞘的保持率有所降低。用浓度为200g/L盐液替代了浓度为454g/L的糖液,对线虫回收率无影响,但成本可以降低。 相似文献
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人参疫病病原菌的研究 总被引:6,自引:0,他引:6
人参疫病是我国人参、西洋参、三七上最重要的病害之一。它不仅为害植株的茎叶,而且还能引起参根腐烂,造成严重损失。 相似文献
999.
ABSTRACT Investigations were conducted to determine whether the effects of tillage practices on the prevalence of brown stem rot of soybean (caused by Phialophora gregata), Heterodera glycines, and Phytophthora sojae were confounded by soil texture in samples collected in the fall of 1995 and 1996. Soil and soybean stem samples, along with tillage information, were collected from 1,462 randomly selected fields in Illinois, Iowa, Minnesota, Missouri, and Ohio in collaboration with the National Agricultural Statistics Service. The incidence of brown stem rot was determined from 20 soybean stem pieces collected from each field in a zigzag pattern. The detection frequency of P. sojae (expressed as percent leaf disks colonized) and population densities of H. glycines were determined from soil cores also collected in a zigzag pattern. The soil samples were grouped into various textural classes, and the effect of soil texture and tillage relations on the activities of each pathogen were determined. Both tillage and soil texture affected the incidence of brown stem rot; however, there was no interaction between tillage and soil texture. Conservation tillage had a greater (P < 0.05) incidence of brown stem rot in clay loam and silty clay loam than did conventional tillage. The detection frequency of P. sojae was not affected by tillage, but a tillage x texture interaction (P = 0.013) indicated that the effect of tillage depended on soil texture. There was a greater (P < 0.05) detection frequency of P. sojae in conservation tillage than in conventional tillage in silt loam and loam soils. However, in sandy loam, the detection frequency of P. sojae was greater (P = 0.0099) in conventional tillage than in conservation tillage. Population densities of H. glycines were significantly affected by both tillage and soil texture, but overall, there was no tillage x texture interaction. There was an inverse relationship between population densities of H. glycines and percent clay (r = -0.81, P = 0.01) in no-till fields, but little or no change in nematode densities was observed with increasing clay content in tilled fields. Population densities of H. glycines were less (P < 0.05) in no-till fields than in tilled fields in silty clay loam and clay soils. There was no difference in H. glycines densities between the tillage categories in soils sandier than silty clay loam or clay. The findings emphasize the need for cautious interpretation of the effects of tillage practices on diseases and pathogens in the absence of information on soil texture. 相似文献
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