短期NaHCO3胁迫对3种冷季型草坪草生理生态特征的影响

土壤盐渍化严重威胁草坪草的可持续发展,选育和种植耐盐草坪草可改良和利用大面积盐渍土壤。以3种冷季型草坪草黑麦草(Lolium perenne L.)、高羊茅(Festuca arundinacea L.)和早熟禾(Poa pratensis L.)为试验材料,采用盆栽法研究不同浓度NaHCO3胁迫(0,0.2%,0.4%,0.6%,0.8%,1.0%)对3种冷季型草坪草生理生态特征的影响。结果表明:不同浓度NaHCO3胁迫下3种冷季型草坪草草坪外观质量、叶片萎蔫系数、叶片相对含水量、叶片叶绿素含量和K+含量均随着NaHCO3浓度的增加而逐渐降低,且浓度越高,下降越明显;0.4%～1.0%NaHCO3胁迫降低了3种冷季型草坪草的地上部分和根系干重,且随着NaHCO3浓度的增加,生长受到胁迫的抑制程度显著增大,根系部分的受抑制程度比地上部分更明显;不同浓度NaHCO3胁迫下3种冷季型草坪草叶片相对电导率、脯氨酸含量、丙二醛含量和Na+含量随着NaHCO3胁迫浓度的升高呈上升趋势,且浓度越高上升越明显;NaHCO3浓度0.4%时,3种冷季型草坪草已受到伤害;黑麦草、高羊茅和早熟禾在不同浓度NaHCO3胁迫下的隶属函数平均值均表现为早熟禾黑麦草高羊茅,说明3种冷季型草坪草抗NaHCO3胁迫的能力均为早熟禾强于黑麦草和高羊茅。     

机收麻山药离散元模型构建及其仿真参数标定

由于麻山药收获过程缺乏有效数值模拟,在很大程度上阻碍了麻山药收获机的设计与优化。该文测定了麻山药的密度、长度、径向尺寸、抗压、抗弯及抗剪强度,基于离散元法建立了麻山药双峰分布模型,并对黏结参数进行校核;以土壤堆积角为响应值,对沙壤土基质间的碰撞恢复系数、静摩擦因数、滚动摩擦因数和表面能4个参数进行标定,建立了土壤堆积角与4个参数之间的回归模型并进行验证,标定了麻山药与钢板、沙壤土间的碰撞恢复系数、静摩擦因数和滚动摩擦因数。试验结果表明,麻山药双峰分布模型能够表征麻山药的力学特性,参数校核得到法向刚度、切向刚度、临界法向应力、临界切向应力及黏结半径分别为9.3×105 N/m、3.0×106 N/m、0.58 MPa、0.14 MPa、3.5 mm;沙壤土基质间的碰撞恢复系数、静摩擦因数、滚动摩擦因数及表面能分别为0.42、0.20、0.30、0.40 J/m3,离散元仿真试验后得到的土壤堆积角与试验结果平均误差为1.48%;麻山药与钢板之间的碰撞恢复系数、静摩擦因数及滚动摩擦因数分别为0.34、0.26、0.049,与沙壤土之间的碰撞恢复系数、静摩擦因数及滚动摩擦因数分别为0.21、0.38、0.075。研究结果可为麻山药机械化收获及产后加工等仿真试验提供一定的理论参考。     

滇中高原华山松林凋落叶枝分解特征对氮的响应

【目的】研究施氮对滇中高原华山松林凋落叶、枝分解特征的影响,为预测未来高海拔区域森林凋落物分解对持续氮增加的响应与适应提供理论依据。【方法】2019年1月-2020年1月,采用尼龙网袋法,以滇中高原华山松林为对象,开展施氮处理下凋落叶、枝原位分解试验,设置对照(N 0 g/(m²·a),CK)、低氮(N 10 g/(m²·a),LN)、中氮(N 20 g/(m²·a),MN)和高氮(N 25 g/(m²·a),HN) 4种处理,分析不同处理华山松林凋落叶、枝质量残留率及木质素和纤维素残留率,在此基础上探讨了华山松林凋落叶、枝质量残留率与木质素、纤维素残留率的关系。【结果】(1)随着分解时间的延长,各处理华山松林凋落叶、枝质量残留率均呈下降趋势。分解1年后,凋落叶质量残留率低于凋落枝,可知凋落叶分解速率快于凋落枝;与CK相比,LN、MN处理凋落叶、枝质量残留率均明显降低,而HN处理则明显提高。(2)与CK的凋落叶分解50%和95%所需的时间(1.764和7.623年)相比,LN处理分别减少了0.018和0.077年,MN处理分别减少了0.009和0.039年,而HN处理分别增加了0.336和1.455年;与CK的凋落枝分解50%和95%所需的时间（4.030和17.417年）相比,LN处理分别减少了0.179和0.774年,MN处理分别减少了0.092和0.396年,而HN处理分别增加了0.171和0.739年。(3)随着分解时间的延长,各处理凋落叶、枝木质素残留率均先降低后升高,纤维素残留率总体呈下降趋势。分解1年时,与CK相比,LN、MN处理促进了木质素和纤维素的分解,而HN处理则抑制其分解。相关性分析结果表明,华山松林凋落叶、枝质量残留率均与其纤维素残留率之间呈极显著正相关关系。【结论】施氮对华山松林凋落叶、枝的分解有不同程度影响,影响大小与木质素和纤维素分解对施氮的响应有关。     

丁香酸对不同品种烟草苗期根系生长的影响

为探究最新发现的植物源生物硝化抑制剂丁香酸对烟草品种K326和云烟85苗期根系生长的影响,通过基质培养试验,设置0、10、25、50、100、200 μmol/L 6个丁香酸浓度,研究了不同浓度丁香酸在不同时间(3 d和5 d)对K326和云烟85主根伸长量和一级侧根发育的影响。结果表明:与对照(0 μmol/L)相比,25～100 μmol/L丁香酸能促进K326主根伸长,在3 d时促进率为13.33%～30.67%,在5 d时促进率降为8.54%～22.55%,最适浓度为50 μmol/L;10～50 μmol/L丁香酸促进云烟85主根伸长,在3 d时促进率为7.81%～18.75%,在5 d时促进率维持在4.10%～10.66%,最佳促进浓度25 μmol/L;丁香酸对两个烟草品种主根伸长的促进效果均为3 d优于5 d。在侧根发育方面,低浓度丁香酸能显著促进K326和云烟85一级侧根数,两个品种促进侧根发育的最适浓度均为25 μmol/L。相关性分析表明,丁香酸处理下两个烟草品种苗期的主根伸长变化率与侧根数变化率呈显著正相关。可见,适宜浓度的丁香酸对两个典型烟草品种苗期主根增长和...     

对建筑工程设计中存在问题的探讨

建筑工程设计是确保建筑工程质量的基础。若建筑工程设计不到位,则会直接影响工程的质量和进度。本文着重对建筑工程设计中常见的问题进行探讨,并提出解决问题的相应策略,旨在与同行交流,共同提高。     

基于灰色关联分析模型的林业产业结构调整研究——以湖南省湘西自治州为例

应用灰色关联分析模型对2005—2012年湖南省湘西州的林业系统的产值结构进行了研究。结果表明,2005—2012年湘西州林业三次产业各产值与其林业总产值的灰色关联度排序为第一产业第三产业第二产业。解释了产生此排序的的原因,同时,结合定性分析方法,分析了湘西州林业产业的现状,指出了湘西州林业产业结构调整存在的问题,并有针对性地提出相应的调整建议,这对于巩固集体林权改革成果,协调湘西州林业生态保护与林业产业发展的关系,以及进一步深化改革有一定的借鉴作用。     

当涂民歌非物质文化遗产保护与传承的调查研究

当涂民歌是流传于皖江两岸的民间歌曲，历史悠久、底蕴深厚，2006被列入国家首批非物质文化遗产名录。近年来，对当涂民歌的保护与传承在政府、团体、个人等多个层面以多种方式呈现，并充分体现出各层面之间的相互关联与密切合作。特别是当涂民歌艺术馆在发展企业自身的同时，借助行政部门提供的平台、渠道，开展当涂民歌的保护与传承工作，形成了一种可持续的良性发展模式。这种行政主导、社会广泛参与的互助互利成功经验值得思考与借鉴。     

宁夏鸟类新纪录遗鸥繁殖群及其生境初探

2016年5月25日在宁夏回族自治区双猫头湖发现了遗鸥。2016年和2017年,利用无人机监测与定点观察相结合的方法,对遗鸥新的繁殖群、繁殖地进行了考察。计数遗鸥810只,约410个繁殖对。繁殖地为湖上2个岛,植被稀疏。另观察到其他鸟类48种。遗鸥食物来源为数量巨大的摇蚊类和豆娘。此次发现为遗鸥在我国繁殖地的新发现。     

The production of short chain fatty acid and colonic development in weaning piglets

Weaning process widely affects the small intestinal structure and function in piglets, while the responses of large intestine to weaning stress are still obscure. The purpose of this study was to determine the developmental changes (i.e., short chain fatty acids (SCFAs) concentrations, growth parameters, crypt‐related indices and antioxidant capacity) in colon of piglet during weaning. Forty piglets were weaned at day 21 and euthanized to collect colonic tissues and digesta samples on day 0, 1, 3, 7 and 14 post‐weaning (n = 8). Piglet growth performance was improved (p < .001) on day 7 and 14 post‐weaning. The concentrations of acetate, propionate, butyrate, valerate, isobutyrate, isovalerate and total SCFAs were higher (p < .001) during the late post‐weaning period. The mRNA abundances of SCFAs transporters were greater (p < .001) on day 7 and 14. The absolute and relative weights, absolute length and perimeter of colon were greater (p < .001) on day 7 and 14. Similarly, post‐weaning increases (p < .001) in colonic crypt depth and Ki67 positive cells numbers per crypt were observed during the same period. Colonic crypt fission indices decreased (p < .01), while total crypt numbers increased (p < .001) on day 14 after weaning. Moreover, total SCFAs concentration was significantly associated with colonic growth parameters and Ki67 cells/crypt (p < .001). In addition, catalase content was decreased on day 3, 7, and 14, whereas, the concentrations of total superoxide dismutase (T‐SOD) and manganese‐containing superoxide dismutase (MnSOD) were higher (p < .05) on day 1 and 3 post‐weaning. These results showed that weaning process has a significant effect on colonic growth and development, which might be associated with the change of SCFAs concentrations in colon.     

Effect of chicken egg yolk immunoglobulins on serum biochemical profiles and intestinal bacterial populations in early‐weaned piglets

This study was conducted to test the hypothesis that dietary supplementation with anti‐E. coli, chicken egg yolk immunoglobulins (IgY), may affect early weaned piglet (EWP) intestinal functions and enteric micro‐organisms. One hundred and forty‐eight ([Landrace × Yorkshire] × Duroc) piglets, weaned at age day 21, were randomly assigned to receive one of three diets for 14 days. Treatment group one (control group) was fed the base diet. Treatment group two (antibiotics group) was fed the base diet which was supplemented with 100 ppm colistin sulphate and 15 ppm enramycin; treatment group three (IgY group) was fed the base diet which was supplemented with 500 mg/kg anti‐E. coli IgY. The study evaluated the effects on EWPs of IgY on growth, serum biochemical, inflammatory profiles and also digestion content intestinal bacterial populations. Results showed no significant difference in diarrhoea rates between IgY‐fed EWPs and antibiotic‐treated EWPs. Serum biochemical analysis showed that EWPs fed an IgY‐containing diet had both lower (p < 0.05) cholesterol and low‐density lipoprotein compared to antibiotic‐treated EWPs. Escherichia coli populations measured in IgY‐fed EWP ileal contents, compared to the control group, were significantly reduced (p < 0.05). Enterococcus, Lactobacillus, Clostridium and Bifidobacterium populations were unaffected by the IgY treatment. Larger (p < 0.05) Enterococcus populations and lower (p < 0.05) expression levels of heat‐stable enterotoxin b (STb) were observed in IgY‐fed EWP caecal digesta compared to the control group. Enteric Lactobacillus significantly decreased (p < 0.05) in EWPs fed antibiotics while it was unaffected by IgY treatment. Dietary supplementation with anti‐E. coli IgY has the potential to suppress enteric E. coli growth, but not Lactobacillus, Clostridium and Bifidobacterium. This promotes and maintains a healthy EWP intestinal environment. These findings suggest that IgY may be used as an alternative to antibiotics in EWP diets.