模拟干旱胁迫下几种冷季型草坪草抗旱性比较研究

研究了3种冷季型草坪草的6个品种在PEG-6000模拟干旱胁迫条件下的生长表现和生理指标。结果表明:高羊茅品种“家园”在干旱胁迫条件下具有较好的生长表现、在土壤中的根系分布最深、且能维持较高过氧化氢酶活性,与其他供试品种相比具有较强的抗旱能力。     

Different crop rotation systems as drivers of change in soil bacterial community structure and yield of rice, <Emphasis Type="Italic">Oryza sativa</Emphasis>

Intensive cropping, especially of rice, is considered to contribute to negative effects not only on soil chemical and biological properties but also on long-term grain yield. Appropriate crop rotation is often practiced as an alternative strategy to overcome the negative side effects of intensive cropping. Although soil microbial diversity and community structure have been shown to respond differently to altered agricultural management practices, little is known about possible links between crop rotation and grain yield on bacterial communities in rice paddy soil. In this study, we investigated the impact of specific rotational crops and compared it with intensive rice cultivation. The main crop rice (Oryza sativa) was rotated with maize (Zea mays) and mungbean (Phaseolus aureus) in different combinations in a system cultivating three crops per year. Soil bacterial communities were studied in two different cropping periods using pyrosequencing of the variable V4 region of the 16S rRNA. Our results showed that rotation with alternative crops increased rice yield by 24–46% depending on rotation structure and that bacterial community structure was altered in the presence of mungbean and/or maize compared to that in rice monoculture. In the crop rotation systems, composition, abundance, and diversity of soil bacterial communities were significantly different and higher than those in rice monoculture. Our results show that effects of crop rotation relate to changes in soil bacterial community structure suggesting that appropriate crop rotations provide a feasible practice to maintain the equilibrium in soil microbial environment for sustainable rice cultivation.     

不同玉米(Zea mays)品种对镉锌积累与转运的差异研究

选取20个玉米(Zea mays)品种作试验材料,通过田间试验研究了镉-锌(Cd-Zn)复合胁迫下玉米的生长发育及其积累和转运Cd、Zn的差异,以期筛选出Cd、Zn低积累的玉米品种。结果表明,Cd-Zn复合胁迫下,玉米的株高、叶面积、生物量、产量以及玉米根、茎叶和籽粒中Cd、Zn含量在品种间均表现出显著差异。有2个品种籽粒的Cd含量超过国家食品卫生标准(≤0.2 mg·kg-1),13个品种茎叶的Cd含量超过国家饲料卫生标准(≤0.5 mg·kg-1),所有品种籽粒和茎叶的Zn含量均符合国家食品卫生标准(≤50mg·kg-1);有7个品种的Cd富集系数1,13个品种茎叶转运系数1,所有品种籽粒转运系数均1;20个玉米品种Zn的富集系数均1,有18个品种茎叶转运系数1,6个品种籽粒转运系数1。根据玉米生物量、产量、籽粒Cd和Zn含量、富集系数、转运系数等指标进行评价,认为红单6号、红育1号、云优78、平单2号、屏单2号5个品种可作为Cd低积累玉米品种,雅玉98可作为Zn低积累玉米品种,可分别在个旧地区Cd、Zn中、轻度污染土壤上推广种植。     

超高压加工软包装柿子酱生产工艺研究

为了解决柿子酱热杀菌返涩问题,采用正交试验法确定了乙烯利脱除柿子涩味和超高压杀菌处理软包装柿子酱的最佳工艺条件。通过感官评价、耐藏性试验、微生物卫生指标检验、稳定性鉴定,研究了超高压处理柿子酱的安全、稳定性。结果表明:柿子用300 mg/L乙烯利溶液浸润10 s后于30℃密封脱涩5 d,柿子脱涩效果最好;脱涩后的柿子酱于25℃经400 MPa杀菌20 min,能明显延长柿子酱的货架期,有效地消除了脱涩柿子酱的返涩和变色现象。超高压非热杀菌技术能安全有效地防止脱涩柿子酱的返涩,延长柿子酱的货架寿命,保持柿子酱的原有色泽和组织结构。     

负压给水技术研究初探

我国水资源短缺,发展节水高效农业已成为现代农业可持续发展的必经之路.负压给水技术是一种新型的灌水技术,与传统灌溉方式相比,它具备节水、节能、精准、高效等多项优势.分析了负压给水技术的优点和技术难点,介绍了负压给水的研究进展.     

代乳粉添加甘露寡糖对7—28日龄湖羊羔羊胃肠道发育的影响

【目的】探讨代乳粉中添加甘露寡糖(mannan oligosaccharides,MOS)对7—28日龄湖羊羔羊胃肠道生长发育的影响。【方法】选择同质性良好的7日龄湖羊公羔(双羔)30只,随机分为2组,每组15只,每只为1个重复,对照组羔羊饲喂不含MOS的代乳粉,试验组羔羊饲喂含0.2%MOS的代乳粉,试验期21d。羔羊28日龄时,两个试验组各随机选择8只羔羊屠宰,取出消化道,称量各胃室和肠段包含内容物的质量和净质量,量取各肠段长度,用以计算各部位的相对质量和内容物分布,以及各肠段的相对长度。多聚甲醛固定皱胃胃底腺区及十二指肠、空肠和回肠中段的组织样品,测定组织形态和小肠上皮细胞凋亡率。采集十二指肠、空肠和回肠的黏膜样品,测定紧密连接蛋白1 (claudin 1)、闭锁小带1(zonula occludens-1,ZO-1)和闭锁蛋白(occludin)的mRNA表达量。【结果】除空肠相对长度外(%全肠长度,P=0.040),MOS对羔羊胃肠指数(%活体质量)、胃肠相对质量(%全胃质量、%全肠质量和%全胃肠质量)、肠道相对长度(%全肠长度)、内容物相对活体质量(%活体质量)、胃肠内容物...     

Long-term study of aerobic bacteria of the genital tract in stud dogs.

The aerobic bacterial flora of the genital tract was characterized in 15 stud dogs in an 18-month study. The dogs represented 4 breeds and were from 3 kennels. Bacterial samples from the prepuce and semen were collected every month, except in connection with matings, when they were collected weekly (464 samples). The dogs that were included all mated at least once during the study. The mean pregnancy rate, litter size, and pup mortality for the bitches with which they had mated were all within normal limits. The most frequent bacteria isolated from the prepuce and semen were Pasteurella multocida, beta-hemolytic streptococci, and Escherichia coli. There was a tendency for breeds to differ in frequency of the most common bacterial species. Bacterial culture yielded no aerobic growth in 14.2% of the preputial samples and 69.8% of the semen samples. Bacteria were transferred between dog and bitch at mating. In this study of healthy breeding dogs, neither the fertility of the dog nor that of the bitch was affected by the bacteria transferred.     

柠檬酸对蛋鸡消化道内容物pH和盲肠菌群的影响

选择20周龄宝万斯高兰褐蛋鸡810只,进行6处理3重复单因子试验,分别饲喂添加0(对照组), 0．5,1．5．2．5,3．5和5．5 g／kg柠檬酸(CA)的日粮,于试验第1,2,10和15周周末分别从对照组,0．5．2．5和5．5 g／kg CA添加组每重复选取一只鸡宰杀,测定其消化道内容物pH和盲肠菌群数,研究CA对蛋鸡H粮、消化道pH和盲肠微生物菌群的影响。结果表明,添加0．5～5．5 g／kg CA可显著(P<0．05)或极显著(P<0．01)降低日粮pH;5．5 g／kg CA在添加1周时可显著降低肌胃pH(P<0．05),其余添加组鸡肌胃、小肠、盲肠pH无显著差异(P>0．05);添加2．5,5．5 g／kg CA可有效降低盲肠大肠杆菌数,5．5 g／kg CA在添加1周时可显著提高盲肠乳酸杆菌数(P< 0．05),之后这种作用随添加时间的延长而减小。     

纳罗克非洲狗尾草种子产量构成因子分析

为了解纳罗克非洲狗尾草单株种子产量构成因子,探索提高种子产量的解决途径,试验选择7个纳罗克非洲狗尾草单株种子产量构成因子;另取4个单株穗子10等分,从基部依次编为1-10号,试验中脱落的种子为11号。单株种子产量构成因子相关性分析结果表明,纳罗克非洲狗尾草单株种子产量(W)与生殖枝数(X₃)呈极显著正相关(P<0.01),与分蘖数(X₂)呈显著正相关(P<0.05);多元逐步回归单株种子产量W=-16.59156+0.42479X₃-0.03082X₅+0.04923X₆。对穗子不同部位的种子分析结果表明,试验中脱落的种子11号质量最好,其次为7号种子。不同部位的种子产量以1、3、8号种子产量较高,而9、10号种子产量最低。提示,纳罗克非洲狗尾草穗子中部的种子产量较为稳定,产量也较高,而穗尾1/3部的产量最低,收种时应确定以穗子中部的种子成熟为最佳收种时机。