白兰修剪截口愈合生长研究

以白兰(Michelia alba)为试材,于2013年12月对其10~20、20~30、30~40mm这3个直径的枝条进行疏枝试验,并于2014年3、6、9、12月跟踪测量截口的愈合程度,研究了截口直径、季度变化对其愈合的影响,以期为园林树木修剪工作提供理论依据。结果表明:截口愈合速度与园林树木年生长物候相一致;20~30mm直径的截口愈合效果明显优于另2个直径的截口,是较理想的疏枝直径。     

Mycosphaerella species associated with leaf disease of Eucalyptus globulus in Ethiopia

Eucalyptus spp. are among the most widely planted exotic trees in Ethiopia. Several damaging leaf pathogens are known from Eucalyptus spp. worldwide. Of these, Mycosphaerella spp. are among the most important, causing the disease known as Mycosphaerella leaf disease (MLD). Characteristic symptoms of MLD include leaf spot, premature defoliation, shoot and twig dieback. Recent disease surveys conducted in Ethiopian Eucalyptus plantations have revealed disease symptoms similar to those caused by Mycosphaerella spp. These symptoms were restricted to E. globulus trees growing in several localities in south, south western and western Ethiopia. The aim of this study was to identify the fungi associated with this disease. This was achieved by examining ascospore germination patterns, anamorph associations and sequence data from the Internal Transcribed Spacer (ITS) region of the rRNA operon, for representative isolates. Several different ascospore germination patterns were observed, suggesting that more than one species of Mycosphaerella is responsible for MLD on E. globulus in Ethiopia. Analysis of sequence data showed that three Mycosphaerella spp., M. marksii, M. nubilosa and M. parva were present. This is the first report of these three species from Ethiopia and represents a valuable basis on which to build further studies in the region.     

Prevalence and antimicrobial resistance profiles of <Emphasis Type="Italic">Salmonella enterica</Emphasis> serovars isolated from slaughtered cattle in Bahir Dar,Ethiopia

A study was undertaken from October 2006 to March 2007 to determine the prevalence and antimicrobial resistance patterns of Salmonella serovars. Liver, mesenteric lymph nodes, intestinal content, and carcass swab samples (each n?=?186) were collected from 186 apparently healthy slaughtered cattle at Bahir Dar abattoir. Bacteriological analysis was done according to the International Organization for Standardization (ISO 6579 2002). Isolates were serotyped at Agence Française de Securite Sanitaire des Aliments, Cedex, France. Twenty-eight isolates consisting of Salmonella Typhimurium, Salmonella Newport, Salmonella Haifa, Salmonella Heidelberg, Salmonella Infantis, and Salmonella Mishmarhaemek were identified. Salmonella Typhimurium and Salmonella Newport were most frequently isolated while Salmonella Heidelberg and Salmonella Mishmarhaemek were isolated least. Eleven of the 28 (39.3%) were resistant to one or more of the antimicrobials tested. Resistance was shown to ampicillin, chloramphenicol, gentamycin, norfloxacin, polymyxin-B, streptomycin, tetracycline, and trimethoprim. Four of 11 (36.4%) were multiple antimicrobial resistant. All the isolates tested were susceptible to the antimicrobial effects of gentamycin, norfloxacin, and trimethoprim. Eleven, four, and two isolates of the 28 were resistant to streptomycin, tetracycline, and ampicillin, respectively. All isolates of Salmonella Infantis, Salmonella Typhimurium (except one), and Salmonella Mishmarhaemek were susceptible to the tested antimicrobials. One Typhimurium isolate was resistant to chloramphenicol, streptomycin, and tetracycline. Salmonella Haifa was multiply antimicrobial resistant to ampicillin, tetracycline, and streptomycin. All isolates of Salmonella Heidelberg were resistant to streptomycin. Results of this study indicated high level of carcass contamination with antimicrobial-resistant Salmonella serovars which could pose public health risk; suggests need for hygienic slaughtering operations and proper cooking of meat before consumption. Further detailed studies involving different abattoirs, animal products, food items, and animals on different settings were recommended in the study area.     

Growth performance and gum arabic production of Acacia senegal in northwest lowlands of Ethiopia

Despite the wide distribution of natural stands of Acacia senegal in Ethiopia, commercial exploitation of gum arabic is constrained by lack of tapping and development techniques. We evaluated the gum arabic yield from natural stands of A. senegal and the growth of 6 provenances in different parts of the country. For the gum yield evaluation from natural stands, four tapping positions and three tapping seasons were tested in a factorial RCB design. The second experiment in Metema evaluated survival and growth of six provenances. A. senegal trees in natural stands respond well to tapping if tapped during the appropriate season and at the correct position on the tree. The mean gum yield did not vary significantly by tapping season (p=0.63). Higher mean yield was, however, collected from trees tapped in October (96 g·tree^?1 per two harvests). The mean yield differed significantly (p=0.009) between the tapping positions. Mean separation (α=0.05) shows that trees tapped at mid stem gave higher yield (160 g·tree^?1 per two harvests). The interaction effect of tapping season and position was not significant. Higher mean yield ((70 ± 112) g·tree^?1) was recorded in mid October-mid stem in two harvests. The second experiment indicated statistically significant difference in mean survival (p=0.0298), height (p=0.000) and root collar diameter (RCD), (p=0.012) between the six provenances. Highest survival, height and root collar diameter growth was observed from Abderafi provenance (100%, (148±11) cm, (38±11) mm, respectively). We recommend October and mid-stem and branches as appropriate tapping season and position. We recommend planting of the Abderafi provenance for the study area due to its superior growth and survival. Our study contributes to the proper selection of provenances for plantation development and improved tapping technology for better production of gum arabic in the country.     

黄蝉属植物研究现状及其园林应用

黄蝉属(Allamanda L.)植物是重要的观赏植物。综述了黄蝉属植物种质资源及其系统学、生理生态特性、药理作用、杀虫活性和栽培繁殖等方面的研究现状,归纳总结该属植物在园林中的配置应用情况,并对该属植物今后的研究方向进行展望。     

Impact of variable-rate application of nitrogen on yield and profit: a case study from South Africa

The response of maize (Zea mays) to banded variable-rate nitrogen (N) application over a period of 3 years (2002/3–2004/5) is analyzed. The experimental design alternated variable-rate (VR) and single-rate (SR) applications of N. The yield monitor data were spatially autocorrelated and therefore were analyzed with spatial regression methods. The baseline spatial regression model defined in this study showed that the VR treatment, treatment by year and treatment by management zone were statistically significant. Sensitivity tests were applied; the first showed that VR treatment had a yield advantage when soil depth was greater than the field average of 174 cm. The second test showed that the VR N rates applied were close to those that would maximize profit. Partial budgeting indicates that benefits from VR vary from year to year, but in this test VR was slightly more profitable than uniform rate application. Economic sensitivity testing indicates that farm size and the price of maize are the key factors in the profitability of VR N.     

Comparative evaluation of effective microbe– and urea molasses–treated finger millet (Eleusine coracana) straw on nutritive values and growth performance of Washera sheep in northwestern Ethiopia

An experiment was carried out to comparatively evaluate the effect of effective microbe (EM)– and urea molasses (UM)–treated finger millet straw (EMTFMS and UMTFMS, respectively) on nutrient utilization and growth performance of Washera lambs. Twenty yearling intact male Washera lambs with an initial body weight of 21.13?±?1.77 kg (mean ± SE) were used for feeding and digestibility trial. These lambs were grouped into five blocks of four animals and randomly assigned to four dietary treatments. The four experimental feeds were untreated finger millet straw (control) + 150 g wheat bran (WB) (T1), untreated finger millet straw + 150 g WB + 150 g Noug seed cake (NSC) (T2), UMTFMS + 150 g WB + 150 g NSC (T3), and EMTFMS + 150 g WB + 150 g NSC (T4). The lambs were de-wormed and vaccinated against ecto- and endo-parasites. Data were analyzed using ANOVA procedure of SAS. Results showed that crude protein (CP) content of finger millet straw (FMS) was improved from 2.13 to 9.7% in UM treatment and 2.13 to 2.39% in EM treatments. Total DM, CP, and OM intake were higher in lambs assigned in UMTFMS (P?<?0.01) and EMTFMS (P?<?0.01) than the control groups and significantly highest (P?<?0.01) in UMTFMS. A non-significant (P?>?0.05) difference was observed between treatment technologies in all nutrient apparent digestibility and average daily weight gain. Therefore, it can be concluded that both treatments could serve as an alternative measure to improve nutritive value of finger millet straw, but due to environmental effect, EM treatment could be safe.

     

银耳生物学特性的研究

银耳(Tremella fuciformis Berk)孢子接种在琼脂培养基上萌发出菌丝,而后再把菌丝培养成银耳子实体。把银耳菌和耳友菌分剔接种在木村培养基上,都不会生长出银耳子实体。银耳菌和耳友菌混合接种在木材培养基上,就能生长出银耳子实体。因此银耳纯种不宜作为银耳生产中用的菌种,栽培上一定要用银耳混种。试验结果还表明银耳不是木腐菌。     

Effects of Farmyard Manure and Inorganic Fertilizers on Sorghum Growth,Yield, and Nitrogen Use in a Semi-Arid Area of Ethiopia

A field experiment was conducted to assess the effect of the combined use of farmyard manure and inorganic fertilizer on the growth and yield of sorghum and on soil chemical properties in a semi-arid area in northeastern Ethiopia. Twelve treatments comprising factorial combinations of four levels of farmyard manure (0, 5, 10, and 15 t ha^?1) and three levels of inorganic fertilizers (0%, 50%, and 100% of the recommended rate) were compared in a randomized complete block design with three replications over a period of six years. The results revealed significant improvements in the growth and yield of sorghum due to the main and interaction effects of farmyard manure and inorganic fertilizer application. The combined application of farmyard manure and inorganic fertilizers increased post-anthesis dry-matter production by 147%–390% and grain yield by 14%–36%. The main effects of farmyard manure and inorganic fertilizers increased stover yield by 8%–21% and 14%–21%, respectively. Farmyard manure application increased total nitrogen (N) uptake by 21%–36%, grain protein yield by 8%–11%, and grain protein concentration by 20%–29%. Application of farmyard manure along with 50% of the recommended inorganic fertilizer rate resulted in a grain yield equivalent to, or greater than that for 100% of the recommended inorganic fertilizer rate, thus effecting a 50% savings of inorganic N and phosphorus (P) fertilizer. Application of 5, 10, and 15 t farmyard manure ha^?1along with 100% of the recommended fertilizer rate and 5, 10, and 15 t farmyard manure ha^?1 along with 50% of the recommended fertilizer rate can be recommended for farmers who can and cannot afford to buy inorganic fertilizers, respectively.     

大蒜新品种成蒜早的选育

成蒜早大蒜是从地方良种二水早中经多代选育而成的早中熟大蒜新品种，株高５８．７５ｃｍ，单株叶片数１４片，叶色深绿，单薹重１４．４４ｇ，鳞瓣数１０．７个，从播处到采收１１９天，一般６６７ｍ＾３蒜薹产量４００－４５０ｋｇ，蒜头产量３００－３５０ｋｇ。