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81.
82.
与香蕉种质离体保存相关的几个遗传学问题 总被引:2,自引:2,他引:2
目前香蕉种质的离体保存主要有缓慢生长保存和超低温保存两种方法。综合有关文献综述和讨论了香蕉种质离体保存过程涉及的遗传多样性、遗传稳定性和完整性、适应等遗传学问题。在开展香蕉种质离体保存的过程中,对离体保存所带来的遗传学方面的影响加以重视并设法减少其影响十分重要:(1)香蕉的生物学特性决定了香蕉种质的离体保存主要以始于吸芽茎尖的培养物作为保存材料;为减少取样环节样本容量较小带来的影响,建议保存数量较大的种质份数。(2)离体保存尤其是缓慢生长保存会引起香蕉种质的遗传不稳定性,因此有必要进行定期的检测。目前香蕉种质遗传稳定性的检测方法主要有形态鉴别、超微结构的观察、同工酶分析和分子标记等。(3)与缓慢生长保存相比较,超低温保存除了在保存过程中香蕉种质遗传稳定性较高,在实现对香蕉种质的长期保存方面也具有明显的优越性。 相似文献
83.
The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand 总被引:4,自引:0,他引:4
Glenn H. Stewart Maria E. Ignatieva Colin D. Meurk Richard D. Earl 《Urban Forestry & Urban Greening》2004,2(3):149-158
Christchurch, the second largest city in New Zealand is a planned city on a coastal plain on the east coast of the South Island. The birth of the city and the subsequent century of development was characterised by colonial values and tree and garden planting with familiar European species along with those from Australia, North America, and eventually all other continents. The image of an “English garden city” with classical parks of oaks and willow-lined rivers became the accepted norm and the way in which the city has been promoted to potential tourists. Gardening is one of the top two recreational activities and exotic species greatly outnumber native species in the flora and in gardens. This has had serious consequences for the highly fragmented and degraded indigenous vegetation and its co-adapted wildlife. A few hardy indigenous species continued to regenerate through this period, but since the 1970s, there has been a progressive change of attitude and interest in reclaiming the natural heritage of the city, manifest in widespread private and public planting of indigenous species and active habitat restoration. In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on shrub and tree regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban environments, combined with the greater density of indigenous seed sources, has allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats – from neglected gardens to pavement cracks to exotic plantations. This is despite the competition from the prodigious seed banks and density of exotic trees, shrubs, and ground covers and albeit minimal impacts of introduced browsing and seed eating mammals. If the present trends continue through appropriate management and facilitation, these tentative signs of native forest regeneration should eventually proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region. 相似文献
84.
将蜡蚧轮枝菌Vp菌株在PDA培养基上23℃黑暗培养,分别于第5、15、20、25、30天后采收。将不同时间采收的分生孢子置于2%葡萄糖培养液内培养,16 h后检测其萌发率,结果表明,采收于第5天和第15天的分生孢子萌发率分别达到89.76%和94.98%,显著高于采收于第25天(30.27%)和第30天(6.12%)的孢子的萌发率;在PDA培养基培养5 d和15 d的分生孢子在相同浓度下对温室白粉虱的致病力分别达到83.40%和74.44%,显著高于培养了30 d的分生孢子的致病力(8.76%)。 相似文献
85.
Improving management for higher reproduction accelerates genetic improvement in closed herd of swine
Masahiro SATOH 《Animal Science Journal》2004,75(6):499-502
The present study compared responses to selection at different conception rates and litter sizes at weaning in a simulated closed herd in a swine breeding program. The base population consisted of 10 males and 50 females, and 10 generations of selection was practiced by using individual phenotype or best linear unbiased prediction of breeding values for a trait with heritability (h2) of either 0.2 or 0.5. The probability of conception in a single mating was assumed to be 0.8, 0.9 or 1.0. Litter size at weaning was sampled randomly from a normal distribution with mean 8, 10 or 12 and variance 8.1225. Genetic response increased by approximately 6% for h2 = 0.2 and approximately 5% for h2 = 0.5 at generation 10 when conception rate was increased from 0.8 to 1.0. However, litter size at weaning did not affect response to selection. In conclusion, improving conception rate by environmental management increases genetic response indirectly in a breeding program of a closed swine herd. 相似文献
86.
The growth and development of plant pathogens and their hosts generally respond strongly to the temperature of their environment. However, most studies of plant pathology record pathogen/host measurements against physical time (e.g. hours or days) rather than thermal time (e.g. degree-days or degree-hours). This confounds the comparison of epidemiological measurements across experiments and limits the value of the scientific literature. 相似文献
87.
几种缓释肥的氮释放特性以及对草坪草生长的影响 总被引:6,自引:2,他引:6
实验室内采用水浸泡法对尿素、3种缓效肥和山西省农业科学院土壤肥料研究所研制(自研草坪肥)的缓效肥的初期溶出率和微分溶出率进行了测定.其中尿素的初期溶出率为22.75%,超出了国际上公认的缓/控释肥的初期溶出率小于15%的指标,而微分溶出率为0.22%,也小于国际上公认的缓/控释肥的微分溶出率(0.25%~2.5%)指标.其他几种缓释肥的初期溶出率为8.73%~14.42%,微分溶出率为0.30%~2.11%,符合国际上公认的缓/控释肥的初期溶出率和微分溶出率指标.田间试验比较和研究了尿素、3种缓效肥和山西省农业科学院土壤肥料研究所研制的缓效肥对草坪草的干草产量和养分含量的影响,尿素和包衣尿素处理的草坪草的生长量前期较高,后期产草量较低,呈马鞍型.其他处理的草坪草干草产量则比较平缓,肥料的氮释放特性与草坪草生长趋势相同.不同肥料处理对草坪草的中量、微量元素含量有一定的影响. 相似文献
88.
随机抽取荷斯坦奶牛 472头 (1~ 11胎 )进行奶牛隐性乳房炎的检测 ,乳用特征性状 (楞角性、尻宽、尻角度、后肢侧视、蹄角度 )的线性评定 ,以及隐性乳房炎与乳用特征的相关性分析。结果表明 :奶牛隐性乳房炎的乳区阳性率与楞角性、尻宽、尻角度、后肢侧视、蹄角度的相关系数分别为 0 1171、0 10 3 0、0 0 681、0 0 180、-0 12 65 ,其中与楞角性、尻宽分别达到显著水平 (P <0 0 5 )的正相关 ,与蹄角度达极显著 (P <0 0 1)的负相关。奶牛阳性率与楞角性、尻宽、尻角度、后肢侧视、蹄角度的相关系数分别为 0 0 967、0 0 5 61、0 0 2 82、0 0 12 7和 -0 0 670 ,其中除与楞角性为显著水平 (P <0 0 5 )的正相关 (0 0 967)外 ,其余均不显著 (P >0 0 5 )。 相似文献
89.
90.
Retrospective Evaluation of the Effect of Heart Rate on Survival in Dogs with Atrial Fibrillation 下载免费PDF全文
B. Pedro J. Dukes‐McEwan M.A. Oyama M.S. Kraus A.R. Gelzer 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):86-92