旱作条件下不同施肥类型和覆膜材料对冀西北马铃薯光合效应、产量和品质的影响

为探究适应冀西北地区旱作马铃薯高产高质的栽培技术,本试验以马铃薯品种京张薯3号为试验材料,研究了在旱作雨养条件下,不同覆膜材料和增施有机肥对旱作马铃薯植株形态、光合效应、产量和品质的影响。试验结果表明：与对照相比,覆膜和增施有机肥处理FOB和FOS可以提高马铃薯出苗率,缩短出苗天数,增加植株株高和茎粗。FOS、FOB和FOW处理在马铃薯块茎形成期、块茎膨大期、淀粉积累期三个时期,显著提高了马铃薯净光合速率、气孔导度和蒸腾速率。从产量和产量构成因素看,FOS和FOB处理单株结薯数比对照分别增加37.9%和25.2%,单株结薯重提高38.1%和33.7%,折合667 m²产量比对照提高31.29%和27.82%。FOS处理马铃薯淀粉含量比对照显著提高21.8%。综合各项指标,对于冀西北坝上地区,增施有机肥+渗水降解地膜是有效的旱作栽培措施。     

鼻气管鸟杆菌病的研究现状

鼻气管乌杆菌痛是近年来新发现的一种感染家禽和野鸟的呼吸道细菌病,主要表现为鸡和火鸡生长迟缓,产蛋率下降、高死亡率、单侧或双侧纤维索性化脓性肺炎、胸膜炎、气囊炎。也常合并、继发新城疫病毒、大肠埃希菌和副鸡嗜血杆菌感染,从而引起急性死亡,危害很大,给养禽业造成严重的经济损失,是一种值得重视的新病。文章对该病的病原、流行病学、症状与病变、诊断方法及预防措施等进行了综述。     

大豆凝集素对小肠上皮细胞和红细胞凝集能力的研究

本文旨在测定纯化的大豆凝集素对兔和鸡小肠上皮细胞和红细胞的凝集活性。测定大豆凝集素对红细胞的凝集能力时,采用2%兔红细胞悬液,测定了使兔红细胞50%凝集的蛋白质浓度。测定对兔小肠上皮细胞的凝集能力时,采用荧光标记SBA与新鲜小肠上皮细胞结合后,观察荧光显微镜下荧光结合细胞比例的方法定量。经血凝试验结果表明,使兔红细胞50%凝集的SBA蛋白质浓度为2.50~3.69μg/mL,而SBA对鸡的红细胞没有凝集作用。SBA对兔小肠上皮细胞有结合能力,结合率为30%左右。试验结果说明大豆凝集素的血凝活性具种属特异性,用SBA与小肠上皮细胞的结合率作为评价其抗营养活性的指标具一定可行性。     

环境因素对淡水浮丝藻生长及产生嗅味的影响

研究温度、营养盐浓度以及光照强度对淡水浮丝藻(Planktothrix sp.)及其代谢产物二-甲基异莰醇(2-MIB)的影响,为控制丝状蓝藻生长及预警水体嗅味物质污染提供实践依据。浮丝藻由中国科学院水生生物研究所淡水藻种库分离于安徽巢湖;设置的实验温度为15、20、25、30℃,BG-11营养盐溶液体积分数为20%、30%、50%、100%,光照为1 000、2 000、3 000、4 000 lx。结果表明,温度对浮丝藻生长密度、总2-MIB生成量及胞外2-MIB分泌量影响最显著,25℃是浮丝藻最适宜生长温度,最高细胞密度可达6.04×10⁵个/mL,30℃是其最适宜的产2-MIB温度,总2-MIB生成量和胞外2-MIB分泌量均最高,分别为3.64×10³ng/L和2.78×10³ng/L;其次为营养盐浓度,增大BG-11营养盐浓度,浮丝藻生长密度和总2-MIB生成量会随之增加,低浓度营养盐时胞外2-MIB分泌量所占比例较高,表明低浓度营养盐更有利于浮丝藻进行胞外2-MIB分泌;光照对浮丝藻生长及产嗅味物质影响较小,...     

两种兼用型牛BoLA-DRA*exon2多态性及其与乳房炎的关联分析

利用PCR-SSCP技术,分析了牛主要组织相容性复合物DRA基因外显子2的多态性在236头中国西门塔尔牛、三河牛中的基因型分布及其多态性与乳房炎的关系。结果表明:经χ2独立性检验,发现该多态片段6种基因型在感染乳房炎牛和健康牛之间分布不一致(p<0.01)。在感染乳房炎牛中CC基因型频率最高,在健康牛中BC基因型频率最高。据此推测,CC基因型可能与这两种牛的乳房炎易感性有关,而BC基因型可能与这两种牛的乳房炎抗性有关。     

不同类型有机物料的有机磷组成及生物有效性

[目的]研究不同有机物料的有机磷组成及其作为磷源施用后的供磷能力,为化肥磷的有机替代奠定理论基础.[方法]供试有机物料包括粪肥类(猪粪、羊粪)、绿肥类(豌豆、苜蓿和绿豆)、秸秆类(小麦秸秆、玉米秸秆和油菜秸秆).分析了8种有机物料的全磷、有机磷含量和C/P值,采用Bowman-Cole方法测定了有机磷中的活性(LOP)...     

Micromorphology of soils in soliflucted materials,Okstindan, Northern Norway

The micromorphology of two soil profiles developed on turf-banked solifluction lobes and a third profile formed on a larger turf-banked solifluction terrace is described. Four elements common to the three profiles are identified.In the horizontal plane the apparent long axes of detrital grains show preferred orientation parallel to the azimuth of the line of greatest slope, and in slides cut in the vertical plane aligned with the slope direction a somewhat stronger preferred orientation (or apparent dip of the grains) is observed parallel, or sub-parallel to the ground surface gradient. Secondly, coatings of matrix material are observed on the upper surfaces of detrital grains at depths greater than 50 cm. Above this depth similar coatings also appear on the sides and lower surfaces of detrital grains. Roughly horizontal flattened patches of matrix enrichment are also observed in the three profiles. These become more frequent with depth, producing a banded pattern of matrix concentrations separated by detrital grains. Finally, large rounded pores, or vesicles, are observed in the upper 25 cm of the three profiles.These micromorphological elements are described, and suggestions are made as to their origins.     

Conservation and the low population density of invertebrates inside neotropical rain forest

Counts of invertebrates by sweep-netting and beating the stratum of rain forest vegetation between 6 in (15 cm) and 6 ft (1·8 m) have been made during rainy season conditions in N. Brasil and on Barro Colorado Island, Panama Canal, the latter from measured volumes of habitat. This work has been repeated on BCI during the dry season. The average population densities of total catches were 0·97 m³ for rainy season and 1·09 m³ for dry season. Species diversity was very high, therefore numbers per species extremely low. It is suggested that such low population density brings hazards of local extinction, and that the maintenance of such a system depends on the existence of extensive habitat from which recolonisation can occur. If this is so, reserves in rain forest will have to be very large, to ensure long-term survival of many of the invertebrate species.     

附生细菌在微囊藻(Microcystis)藻华颗粒上的定殖和生长

通过测定微囊藻模拟藻华颗粒和微囊藻水华藻华颗粒表面附生菌数量的变化,分析微囊藻（Microcystis）与附生假单胞菌（Pseudomonas）之间相互作用关系。结果表明,在死亡藻体的模拟藻华颗粒表面附生菌数量迅速增加,而活藻藻华颗粒表面附生菌数量增长缓慢,在培养后期藻体大量死亡,附生细菌的数量不断增加,最后超过死亡藻体的模拟藻华颗粒的附生细菌数量。附生细菌在天然微囊藻藻华上定殖和生长也呈现类似的趋势,由于附生菌同藻华中微囊藻之间存在竞争,附生菌的存在促进藻体团聚,抑制附生细菌的定殖,但是在微囊藻的衰亡期产生的大量营养物质有利于附生细菌的生长,水体中附生细菌的数量不断增加,同时天然藻华上附生细菌的数量也大量增加,有利于其生长和定殖。