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1.
拉丁美洲和加勒比地区是世界主要的竹资源分布区,以瓜多竹为代表的560多竹种资源占全球竹种的33%,其中巴西、哥伦比亚、秘鲁、厄瓜多尔、墨西哥等国竹林面积和竹种数量位居该地区前列。与亚洲相比,拉丁美洲和加勒比地区现代竹产业发展起步较晚,规模和效益有限。面向未来,该区竹资源主要分布国家的政府正在制定和实施相关政策和战略,助力竹区发展经济、缓解贫困和保护环境。 相似文献
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Daniela Alvarado-Camarillo Ana María Castillo-González Juana C. García-Santiago 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(6):496-504
Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L?1 and K from 7 to 4.2?meq?L?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L?1 respectively, resulted in plants with the greatest dry weight. 相似文献
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This is the first study to investigate the occurrence, risk factors and hematological findings of hemoplasmas in dogs from Chile. Complete blood count and 16S rRNA conventional PCR for Mycoplasma spp. were performed in 278 blood samples from rural (n = 139) and urban (n = 139) dogs in Valdivia. Real time 16S rRNA PCR (qPCR) allowed species identification. Mycoplasma spp. occurrence was 24.8%. ‘Candidatus M. haematoparvum’ (CMhp) was identified in 12.2% and Mycoplasma haemocanis (Mhc) in 11.9% dogs. It was not possible to identify species in two Mycoplasma spp. samples by qPCR. Sequencing allowed identifying one of them as ‘Candidatus M. turicensis’ (CMt). Frequency in rural localities was higher (41.7%) than in urban (7.9%). Rural locality, maleness and older age were risk factors for hemoplasmosis. Hemoplasma-positive dogs had a higher total protein. This is the first report of Mhc, CMhp and CMt in dogs from Chile, with a high occurrence in rural localities. 相似文献
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This is the first study to investigate the prevalence and risk factors associated with Ehrlichia canis and Anaplasma platys positivity in dogs from Paraguay. Conventional PCR assays for the E. canis 16SrRNA gene and A. platys p44 gene were carried out in blood samples from 384 dogs from Asunción city, Paraguay. Sequencing and phylogenetic analysis were performed in selected positive E. canis and (16SrRNA gene) and A. platys (16S and p44 genes) samples. The overall prevalence of E. canis and A. platys in dogs in Paraguay was 10.41% (40/384) and 10.67% (41/384), respectively. Older dogs without veterinary care had higher odds for E. canis positivity and a higher number of dogs in the same household, as well as absence of anti-tick treatment were considered risk factors for A. platys. Ehrlichia canis and A. platys circulate in the dog population from Asunción, and are described for the first time in Paraguay. 相似文献
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美国农业一直处于领先地位,不仅得益于其丰富的自然资源和高科技的农业技术,其合理的农产品分布也不可少的影响因素。中国是一个农业大国,农业的发展离不开农产品,农产品的种植种类、农产品的区域分布、农产品的质量发展都直接影响农产品的发展。美国虽然面积和我国差不多,但因为有合理的布局,农产品贸易一直发展良好。要借鉴美国农产品的发展,研究和分析其农产品分布现状很有必要。 相似文献
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通过比较中美森林法的历史和现状,指出森林法修改和完善的紧迫性且时机已经成熟,以及森林法修改要重视理论研究和实际情况调查。我国森林法修改和完善可以借鉴美国森林法中的森林生态系统管理等先进理念。对美国《国有林管理法》与《中华人民共和国森林法》的结构与体例、立法精神、科学的地位、公众参与等内容进行了比较研究,据此给出一些《中华人民共和国森林法》的修改建议。 相似文献