Effect of nitrogen form and radiation on growth and mineral concentration of two Brassica species

Three greenhouse experiments were carried out to determine the growth, yield, nitrate, total N and S concentration in shoots, and water uptake of hydroponically grown Brassica rapa L. subsp. nipposinica var. chinoleifera and Brassica juncea L. In each experiment, daily photosynthetically active radiation (PAR) level was 5.0 mol m⁻² (low), 6.8 mol m⁻² (medium) or 9.0 mol m⁻² (high). Plants were supplied with nutrient solutions having equal N concentrations of 11 mM in different forms: 100% NH₄, 50% NH₄ + 50% NO₃, and 100% NO₃. Nitrogen supplied as 100% NH₄ reduced fresh and dry shoot biomass, leaf area, and leaf number in both Brassica species, especially at low and medium PAR levels. In both Brassica species, S concentrations were highest, while nitrate concentrations were lowest in leaves of plants grown at N supplied as 100% NH₄. No differences in leaf nitrate concentrations were observed between 50% NH₄ + 50% NO₃ and 100% NO₃ treatments. Low and high PAR levels increased the nitrate concentrations and decreased the N/S ratio in leaves of both crops compared to medium PAR level. Fresh shoot biomass was maximized in Brassica rapa when PAR level was above the medium value and nitrate was supplied in the nutrient solution as NO₃ or as a mixture of 50% NO₃ and 50% NH₄. The highest fresh shoot biomass of Brassica juncea was observed in all nutrient solution treatments at high PAR level.     

Demographic survey of private veterinary practices in western Canada

A workforce survey of private veterinary practices in western Canada was conducted in 2020. Data were obtained on 526 practices (response rate = 39.5%) and 1445 individual veterinary practitioners. Overall, 68.4% of practitioners identified as female, with 4 times as many females as males comprising the youngest age cohorts (26 to 35 y) of the profession. The majority of practices (67.9%) were companion animal, followed by mixed animal (21.9%) and food animal (10.2%). Most females (77.2%) and males (57.8%) were engaged in companion animal practice, whereas 23.5% of males and 6.0% of females were food animal practitioners. During an average work week, practitioners devoted 77.4% of practice time to small animals, 15.1% to food animals, and 7.5% to equine animals. A greater proportion of males (75.2%) versus females (63.2%) worked on a full-time equivalent basis (P < 0.001). Whereas males were 1.7 times (95% CI = 1.3 to 2.3; P < 0.001) more likely to be practice owners than females, 54.5% of females were owners. Practice ownership was lower than in previous surveys, a trend that may have long-term implications with respect to the corporatization of the veterinary profession.     

甘蓝型油菜DH系主要性状及SSR分子标记分析

对173份甘蓝型油菜DH系材料主要农艺性状、品质性状以及SSR分子标记的分析表明,DH系系内性状表现高度一致。农艺性状中,分枝高度的变异系数最大（26.39%）,株高的变异系数最小（9.42%）;品质性状中,芥酸含量变异系数最大（62.86%）,含油量的变异系数最小（5.10%）。SSR分子标记分析发现,DNA谱带符合1∶1分离规律。     

高效液相色谱法测定兽用阿苯达唑片的含量

利用高效液相色谱法测定兽用阿苯达唑片的含量。方法线性范围是10～150μg/mL，r=0．9994，RSD=2．5％。与紫外分光光度法对比，证明高效液相法可鉴别出紫外法不能鉴别的伪劣药品。该法操作简便快速，结果准确可靠。     

不同啃食强度对白沙蒿影响的初步研究

根据飞播区牲畜对白沙啃食程度的不同，采用人工模拟放牧方法对牲畜啃食的嫩枝及绿色部分设置了１０％、３０％、５０％、７０％、９０％、对照６种不同啃食强度的处理，探讨啃食强度对白沙蒿生长的影响。试验结果表明，白沙蒿放牧利用强度控制在３０％以下，有利于白沙蒿的生长，否则会影响其正常生长。     

秦川牛 MYH8基因多态性及其与生长性状的关联分析

为研究秦川牛MYH8基因的多态性及其与秦川牛生长性状的关联性,选取163头健康的30月±2月龄秦川牛,采用DNA测序技术发现MYH8基因外显子上的SNP位点,并以PCR-RFLP技术分析秦川牛群MYH8基因型,研究其遗传多样性,再通过SPSS 19.0软件分析SNP位点与秦川牛体尺性状和胴体性状的关联性。研究结果表明,在MYH8基因第33外显子上存在3个SNP位点,分别在基因序列26 064、26 094和26 100bp 3处,且26 064bp处(TC)为同义突变,26 094bp处(TC)为错义突变,26 100bp处(CG)为错义突变。关联分析显示,C26100G突变发生在体斜长指标,表现为GG基因型个体的群体均值显著高于GC、CC基因型个体(P0.05);而其他突变中不存在显著性差异。某些基因型(T26064C突变处TC基因型和T26094C突变处CT基因型)可能为优势基因型,但还需通过更多个体验证。说明:MYH8基因对秦川肉牛生长性状存在一定影响。     

黄土坡耕地径流水力学参数与侵蚀产沙的模拟

为了明确连续降雨条件下黄土坡耕地微地形的径流产沙及水力学特征,基于4种坡度(5°,10°,15°,25°)、4种耕作方式(直线坡、人工锄耕、人工掏挖、等高耕作)和2种雨强(60mm/h,120mm/h)的组合,通过室内模拟连续90min降雨试验,对不同坡面的径流泥沙特征和水力学参数进行了定量分析和计算。结果表明:4种耕作措施的径流量和产沙量均遵循一致的规律,从大到小均为直线坡人工锄耕人工掏挖等高耕作,直线坡的径流量和产沙量分别是等高耕作坡面的2倍和2.3倍,其水土保持效应依次增强;相同耕作方式下,与60mm/h雨强相比,120mm/h雨强下的径流量由1.04kg/min增大到3.02kg/min,雨强对径流量的影响显著;径流量和泥沙量随时间均呈现对数变化趋势;相同降雨历时下,坡面流随雨强和坡度的增大,从层流和缓流向紊流和急流发展,加剧了水土流失。耕作方式、雨强和坡度是影响黄土坡耕地侵蚀产沙过程及水力学特征的重要因素。因此,通过实施有效的保护性耕作、削弱坡度效应将有助于黄土坡耕地的水土保持。     

处理后的工业污水用于荒山绿化研究

研究处理后的工业污水能否用于荒山绿化.在张家口市桥东区水泉沟瘠薄山地的典型地段设立了一个造林试验点,采用不同的灌溉措施,对臭椿、火炬树、四季玫瑰等3个树种进行了的植苗造林试验.结果表明:不同灌溉措施对不同树种当年的植苗造林成活率及其株高、地径和冠幅等指标的影响差异不显著,经过对土壤相关指标的测定,工业污水(50%)处理...