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采用室内生物测定方法研究了狼毒根粉碎物和茎叶粉碎物在土壤里腐解过程中对小冠花幼苗生长的影响。结果表明,狼毒根对小冠花幼苗株高、幼苗干重和根干重有抑制作用,且随狼毒根用量增多,其抑制作用增强,对小冠花叶绿素含量影响不明显,只有当用量在5克/盆时与对照差异达到极显著水平,对小冠花细胞质膜透性无显著影响。狼毒根的抑制作用强于茎叶,狼毒的生化他感作用主要是通过根起作用。 相似文献
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为了探究狼毒种子对6种草地植物针茅(Stipa copillata)、羊草(Aneurolepidium chinense)、披碱草(Elymus dahuricus)、扁穗冰草(Agropyron cristatum),独行菜(lepidium apetalum)、碱地风毛菊(Saussurea runcinata)种子发芽和幼苗生长的影响,采用培养皿滤纸法分别将不同密度的狼毒种子(0、5、10、20、40粒/皿)和6种草地植物种子(10粒/皿)一起培养,并测定了相关指标。结果表明:随着狼毒种子密度增大,受试种子发芽率,发芽势,发芽指数先增大后减小,且为促进作用,在狼毒种子密度为10粒/皿时促进作用最大,促进作用由大至小依次为披碱草,羊草,扁穗冰草,针茅,碱地风毛菊,独行菜。除碱地风毛菊根长在狼毒种子密度为10粒/皿时存在微弱的抑制作用之外,其他受试植物根长苗长存在不同程度的促进作用。 相似文献
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苏打盐碱胁迫对长穗冰草幼苗生长和K+、Na+含量的影响 总被引：5，自引：0，他引：5
在人工模拟不同pH梯度的苏打盐碱土上种植长穗冰草,旨在探讨长穗冰草苗期耐碱性和盐碱胁迫下K 、Na 含量的变化及其生理响应.结果表明,长穗冰草是一种耐碱性较强的植物,在土壤pH≤10.5的苏打盐碱土上可以出苗和生长.与对照(pH7.5)相比,pH≤8.5的土壤对长穗冰草出苗有促进作用,pH＞10.5时对出苗产生严重抑制,长穗冰草出苗最适宜的pH为8.5.长穗冰草的株高随土壤pH值的升高而下降(r=-0.9406**),地上部干重和分蘖数随土壤pH值的升高而增加(r=0.8834**和r=0.9787**).苏打盐碱胁迫抑制长穗冰草顶端生长优势的同时,促进了幼苗地上部干重与分蘖数的增加.分蘖数可以作为衡量长穗冰草耐碱性强弱的生长指标.随着苏打盐碱胁迫的增强,长穗冰草地上部K 含量不断降低,Na 含量显著升高,K /Na 比值减小,表明Na 含量的升高和K /Na 比值的降低可能是抑制长穗冰草生长的主要原因之一.K 、Na 的含量变化对维持长穗冰草植物细胞的离子平衡起到了积极的调节作用. 相似文献
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在青海省高速公路边坡进行不同牧草与灌木混播试验,结果表明,出苗最快的为苜蓿+扁穗冰草,盖度增加也最快,到2005年9月盖度已达70%,赖草+柠条组合盖度变化较大,从2005年的5%增加到次年的90%,且生物多样性最大,群落稳定性最强。地上植物量(干重)增加最快的组合为扁穗冰草+星星草+沙棘,从2005年9月的40 g/m2增加到2006年10月的1200 g/m2。在短期内,适宜当地阴坡种植的优良组合为扁穗冰草+星星草+沙棘,阳坡为苜蓿+扁穗冰草,不同混播组合的建植效果排序如下:扁穗冰草+星星草+沙棘>苜蓿+扁穗冰草>柠条+赖草>其他。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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Billinghurst RC Brama PA van Weeren PR Knowlton MS McIlwraith CW 《American journal of veterinary research》2004,65(2):143-150
OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis. 相似文献