排序方式： 共有35条查询结果，搜索用时 31 毫秒
21.
《Southern Forests》2013,75(4):267-271
The aim of this study was to compare survival rates and leaf gas exchange of micro- and macro-propagated Eucalyptus grandis × E. nitens, and seed-propagated E. grandis and E. nitens, at a site in Hilton, KwaZulu-Natal, South Africa, where the conditions were suitable for cold-tolerant hybrid eucalypts. Fourteen months after planting, 50% of micropropagated E. grandis × E. nitens had survived, compared with 87% for macropropagated E. grandis × E. nitens, 53% for seed-propagated E. grandis and 93% for E. nitens. Differences in instantaneous leaf gas exchange and parameters derived from the light and CO2responses of gas exchange were not significant between micro- and macro-propagated plants, but were significant between species. All trees used water more efficiently during photosynthesis at 16 months (winter; June 2004) than at 14 months (autumn; April 2004) after planting. However, micropropagation yielded plants that were most vulnerable to the combination of prolonged dry conditions and air frost 相似文献
22.
Winter chilling is a key environmental trigger of floral induction in temperate Eucalyptus. Over the past two decades, considerable site × eucalypt flowering interaction research has been undertaken over a range of high elevation (>1 100?m asl) forestry sites in the South African summer rainfall area. A practical method of accurately monitoring eucalypt bud temperature at remote sites in these areas was needed for this research. Utilisation of traditional methods of air and bud temperature measurement were not viable, due to significant risks of data and meteorological equipment loss posed by severe weather, vandalism and theft. Between 1996 and 2004, a robust structure for housing the miniature Hobo® temperature logger (hereafter termed ‘Hobo pole’) was designed and utilised for in-field monitoring of air temperature in the research trials. During 2009 and 2010, an experiment was conducted to investigate the relationship between E. nitens bud temperature (BudT), Hobo pole air temperature (HoboAT) and radiation screen air temperature (ScrnAT), and develop appropriate calibration models. Attempts to develop a single model for predicting hourly BudT from hourly HoboAT over the entire annual period yielded unsatisfactory results (maximum R?2 value 0.49). Separate winter and summer regression models were subsequently developed for predicting BudT from HoboAT, ScrnAT from HoboAT, and BudT from ScrnAT. In these regressions, R?2 values were generally slightly higher, and SE values lower, for mid-winter data than for mid-summer data. In mid-winter, BudT on HoboAT gave the highest R?2 value (0.99) and lowest SE value (0.49 °C) of all regressions. The Hobo logger/Hobo pole combination, together with developed regression models (presented in this paper), offers one practical, cost-effective solution for accurately monitoring eucalypt bud temperature at remote, high-elevation forestry sites in South Africa. 相似文献
23.
24.
Dugald C. Close Clare McArthur Elizabeth Pietrzykowski Hugh Fitzgerald Steve Paterson 《Forest Ecology and Management》2004,200(1-3):101-112
We examined the effects of nursery and field nutrient treatments on leaf chemistry and browsing during establishment of Eucalyptus globulus (two trials; Cressy and Dunalley) and Eucalyptus nitens (one trial; Tyenna) seedlings. Seedlings had high- or low-fertilizer application treatments in the nursery, were fertilized or not in the field and were individually fenced (used for leaf chemistry sampling) or not (used for browsing assessment). The high-fertilizer nursery treatment resulted in relatively high foliar nitrogen (N) and low tannin content (all seedling types), and high total essential oils (seedling batch planted at Cressy only), but nursery fertilizer level did not affect dry matter, neutral detergent (NDF) or acid detergent fibre (ADF) or lignin. After planting, levels of N, tannins and total essential oils changed over time, but the degree differed between sites. Field fertilizing generally had no effect on leaf chemistry during 10 weeks after planting. Across sites, the pattern of browsing was the same. Seedlings with the high-fertilizer nursery treatment were browsed more than the low-fertilizer nursery treatment, though the difference was only significant at two of the three sites. Thus trends in browsing damage were consistent with differences in foliar N and tannins as a result of nursery- and not field fertilizing treatment. Manipulation of seedling chemistry, using particular fertilizer application regimes in the nursery, may be one tool for managers wishing to decrease seedling damage by browsers, particularly when browsing severity is not extreme. 相似文献
25.
研究了温度和pH值对斜带髭鲷Hapalogenys nitens蛋白酶、淀粉酶活力的影响。结果表明,斜带髭鲷胃内pH值范围为4.9～5.4;肝胰脏pH值为5.8～6.2;肠道pH值为6.5～6.9。蛋白酶活性随温度的上升而增加,在40℃达最大,40℃以上酶活性随温度的上升而下降。在不同消化器官中,蛋白酶活性大小顺序为：胃〉前肠〉幽门盲囊〉后肠〉肝胰脏。在15～50℃范围内,斜带髭鲷消化道不同部位淀粉酶活性的最适温度均为35℃,淀粉酶活性由高到低顺序为：肝胰脏〉幽门盲囊〉前肠〉后肠〉胃。在pH值为2.2～7.6范围内,胃蛋白酶活性的最适pH值为2.8;在pH值为4.8～8.0范围内,其他消化器官蛋白酶的最适pH值均为7.2;在最适pH值下,各消化器官中的蛋白酶活性由高到低顺序为：前肠〉幽门盲囊〉后肠〉肝胰脏。在pH值为4.8～8.0范围内,胃淀粉酶活性的最适pH值为6.0,肠、肝胰脏与幽门盲囊淀粉酶的最适pH值均为6.8,活性由高到低顺序为：肝胰脏〉幽门盲囊〉前肠〉后肠〉胃。在最适温度和pH值下,蛋白酶活性由高到低顺序为：胃〉前肠〉幽门盲囊〉后肠〉肝胰脏;淀粉酶活性由高到低顺序为：肝胰脏〉幽门盲囊〉前肠〉后肠〉胃。 相似文献
26.
There is increasing interest worldwide in using tree harvesting biomass as an energy source. Bark retained on logs is commonly used as an energy source, but is generally removed from eucalypt logs during harvest. In order to evaluate the potential use of eucalypt bark as fuel, there is a need for information on the productivity and cost implications of retaining eucalypt bark during harvest operations. The study examined the impact of retaining bark on logs on the productivity and costs of a whole?tree to roadside harvesting system in a short?rotation Eucalyptus nitens plantation in Australia being harvested for pulp logs. Trees were felled and bunched with a feller?buncher in spring, then left infield for four weeks to promote bark adhesion and reduce bark loss. A skidder extracted the trees to roadside where a processor processed them to predominantly 10?m logs. Machine productivities were calculated from estimated tree and log volumes and cycle times recorded from video recordings. The feller?buncher's productivity (65 m3 PMH0?1) was less than expected as it appeared to be underpowered to handle the larger trees on the study site. The skidder's productivity (56 m3 PMH0?1) was comparable to those reported in studies under similar conditions and with bark retained. The roadside processor's productivity (25 m3 PMH0?1) was lower than expected. This was believed to result from the operator separately stacking 10?m and 5?m logs, and the lower feed speed resulting from slippage due to the reduced feed roller pressure used in the study to reduce bark loss. Future research could identify feed rollers that increase feed speed while retaining bark. Harvest system costs (AUD18 GMt?1) were similar to those reported for a eucalypt roadside processing trial where bark was removed. These results suggest that retaining bark on the logs at roadside did not affect the harvesting system's productivity or costs. 相似文献
27.
《Southern Forests》2013,75(3):155-167
The measurement and statistical analysis of data from eight Eucalyptus nitens trials, established in the summer rainfall forestry region of South Africa during the 1980s and 1990s, have enabled the characterisation of the Institute for Commercial Forestry Research's breeding population. Provenance testing showed that the more northerly New South Wales (Australia) Eucalyptus nitens provenances of Barren Mountain and Barrington Tops are distinctly better suited to the summer rainfall areas of South Africa than the southern New South Wales provenances and the Victorian provenance, Penny Saddle. Generally, the species was not badly affected by Coniothyrium canker. High type B genetic correlations for all site pairs, except one comparison, ranged from 0.75 to 0.99 for diameter at breast height (dbh), indicating very little or no genotype × environment interaction for dbh for the genotypes tested in this study. Narrow-sense heritability coefficients ranged from 0.01 to 0.34, indicating that the species generally exhibited sufficient breeding opportunity for improvement of diameter growth. High genetic correlations of greater than 0.90 between diameter measurements at 52 to 62 months after establishment and diameter measurements at 94 or 113 months were found, indicating that selections can be reliably made at five or six years. Predicted genetic gains were highest in the trials at Goedehoop and Arthur's Seat, with increases in dbh of 3.07 cm (17.1%) and 3.17 cm (20.7%), respectively, at full rotation. 相似文献
28.
采用PCR技术获得我国南海斜带髭鲷(Hapalogenys nitens)养殖及野生群体共50尾样品的mtDNA控制区全序列,长度范围788 ～790 bp;测得序列与GenBank下载的其他鲈形目鱼类D-loop全序列利用CLUSTAL X进行排序后,对控制区结构进行分析.识别了其终止结合序列区、中央保守区和保守序列区,指出了终止相关序列的主体是TACAT与其反向互补序列ATGTA以及一系列保守序列(CSB-F、CSB-E、CSB-D和CSB-1、CSB-2、CSB-3),并给出了其一般形式;此外,基于斜带髭鲷D-Loop全长序列,利用贝叶斯法构建了分子系统进化树.结果显示,斜带髭鲷养殖群体与野生群体部分样品各自紧密聚成一小支,而在整棵进化树上,养殖样品与野生样品相互交错聚集在一起,可见本研究海区斜带髭鲷养殖群体与野生群体之间的遗传差异分化不显著. 相似文献
29.
研究斜带髭鲷和紫红笛鲷在早期发育过程中游泳能力,以及盐度、光照、昼夜时间、饥饿和再投喂对游泳能力的影响,旨在为优化其苗种培育工艺提供技术支撑。结果显示,斜带髭鲷游泳能力指数为:1 cm:48.60;2 cm:122.40;3 cm:242.40;4 cm:397.20。最大巡游速度出现在25~35的盐度区间,盐度越高,影响越显著;不同体长组紫红笛鲷幼鱼的游泳能力指数分别为:1 cm:111.90;2 cm:258.00;3 cm:285.00;4 cm:318.00;且随着游泳时间延长,巡游速度线形下降。在15~35的盐度范围内,紫红笛鲷巡游速度最大,且随着生长,盐度越低对巡游速度的影响越显著;在0~2 460 lx的光照范围中,1,2,3 cm规格的斜带髭鲷巡游速度随着光照度的增加而增加;最大巡游速度出现在清晨,最低巡游速度出现在午夜,且差异显著;而光照对巡游速度的影响随紫红笛鲷生长而减弱;紫红笛鲷的最大巡游速度出现在清晨,其次为傍晚,最低巡游速度出现在午夜。2种鱼在饥饿的前2 d里巡游速度相对对照组有所上升,但随即下降明显。再投喂组的巡游速度随补偿生长的出现相对对照组略有上升。 相似文献
30.
为了建立和优化亮叶蜡梅(Chimonanthus nitens Oily.)的ISSR反应体系,对模板DNA的浓度、引物浓度、Mg2+浓度等影响因子进行了筛选.结果表明:在25 μL的反应体系中,含有40 ng模板DNA、1 U Taq酶、0.2 mmol/L dNTP、0.3μmol/L引物、1.5 mmol/L Mg2+、2.5μL 10×buffer的扩增效果最好.利用该优化的反应体系,筛选出了12条稳定性强、清晰度高、多态性高的ISSR引物,并对筛选出的12条引物在不同退火温度(51～56℃)下的扩增效果进行了比较,从而确定了每个引物的最佳退火温度. 相似文献