保持金边虎尾兰金边不消失的繁殖方法

金边虎尾兰的金边属于嵌合体彩斑，叶插繁殖易使其金边消失。根据相关文献和实践经验，介绍了保持金边虎尾兰金边不消失的4种繁殖方法，其中根状茎扦插是一种新的繁殖方法。     

农田边界植物多样性与生态服务功能研究进展

农业集约化和城市化导致农业景观重要生境发生巨大变化,农田野生动植物数量下降。农田边界作为农业景观中重要的组成部分,其丰富的物种组成,不仅具有重要的生态功能,也具有重要的景观价值。本研究对农业生态系统农田边界植物多样性进行阐述,论述了影响农田边界植物多样性的影响因素和生态服务功能。综述研究显示,农田边界具有类型多样性、物种多样性、植物功能类型多样性及时空结构多样性特征;其影响因素主要包括4个方面：农田边界结构、农田边界管理、周边土地利用影响以及景观结构特征的影响;农田边界生态功能包括：生产、环境保护、野生动植物保护和景观美学功能等;最后总结了不同类型农田边界生态植被营建模式与优化途径,对中国农田边界植被管护提出了一些建议。     

中国对“一带一路”沿线国家农产品出口增长二元边际及其影响因素分析

为研究中国农产品在"一带一路"沿线国家出口增长特征,探究贸易成本对农产品出口增长二元边际的影响,本研究以"一带一路"沿线64个国家为样本,选取1997—2016年中国对"一带一路"沿线64个国家农产品HS-6位编码数据,运用H-K测度方法和核密度估计的估计方法进行研究,探索中国对"一带一路"沿线64个国家农产品出口增长的源泉,进一步深入分析各项贸易成本对于农产品出口增长二元边际的作用。结果表明,中国对"一带一路"沿线国家农产品出口增长扩展边际和集约边际波动较大,扩展边际对农产品出口增长起主要推动作用;经济规模、地理面积、人口密度对农产品出口增长扩展边际和出口增长集约边际均有显著正影响;关税水平、贸易距离、各国进口所需文件数、贸易国建立仓库所需时间、汇率成本和外部冲击对农产品出口增长扩展边际具有显著负影响,关税水平、各国进口所需文件数、贸易国建立仓库所需时间、汇率成本和外部冲击对农产品出口增长集约边际具有显著负影响。     

The household economics of rubber intercropping during the immature period in Northeast Thailand

In order to alleviate poverty in Northeast Thailand, the Thai government has promoted rubber farming, which has expanded at the expense of annual crops. Because of a long immature period, planting rubber represents a loss of income for poor farmers in the very first years. This paper analyzed how rubber intercropping during the immature period helps farmers to compensate for this loss of income. Economic performances of the most widespread rubber farming systems were analyzed using information collected from a questionnaire addressed to 35 farmers in Buriram province. A sub-sample of 22 farmers was further interviewed to estimate the contribution of rubber intercropping in the formation of the total annual income during the immature period. The results showed that interest in rubber intercropping has grown, with cassava and rice as the main associated crops. With additional costs of about 14,169 ?/ha/year over monospecific rubber plantations, rubber-cassava intercropping systems generated a gross margin estimated at 11,340 ?/ha/year for a 3-year period. Compared to a monospecific rubber plantation, rubber-cassava intercropping systems reduced management costs by 59% over the 6-year period of rubber immaturity. The cash-income drawn from intercropping ranged from 0 to 26.8% of the household’s total annual income, which can be of considerable importance for low-income farmers.     

TMDL计划与小流域污染综合治理思路的研究-以南水北调东线山东段治污为例

为了不断完善小流域污染综合治理思路,进一步推进水污染治理工作,对TMDL计划进行了介绍,并在治理思路、总量分配方法及总量分配公平性、合理性等多个方面与小流域污染综合治理思路进行比较,找出差异,吸收其有益的思路和措施。通过比较得出:①小流域污染综合治理和TMDL计划在思路上是一致的,但在总量分配及分配的公平性、水质目标可达性的保证率等方面存在着一定差异;②TMDL计划中的诸多措施可为小流域污染综合治理所吸收借鉴,并以此为基础对完善小流域综合治理提出了诸多合理的建议。     

Fungicide efficacy of dry bean white mold [Sclerotinia sclerotiorum (Lib.) de Bary,causal organism] and economic analysis at moderate to high disease pressure

White mold [Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] is an economically damaging disease of dry bean (Phaseolus vulgaris L.). Producers often require fungicides to control moderate to high disease levels. Evaluation of fungicide efficacy and cost is critical to make cognisant management decisions. Four field studies were conducted at the Huron Research Station, near Exeter, Ontario in 2012 and 2013. Commercially available synthetic fungicides and a biofungicide seed treatment were evaluated for efficacy in suppressing white mold of dry bean and a subsequent economic analysis was conducted. Area under the disease progress curve (AUDPC) was calculated using disease intensity (incidence × severity) ratings. The untreated control and biofungicide seed treatment had the highest AUDPC values, and in addition to the two applications of the low rate of fluxapyroxad + pyraclostrobin and two applications of penthiopyrad, had the lowest yields. The most efficacious products with regard to disease suppression and yield response were two applications of boscalid, all rates of fluazinam and thiophanate-methyl, and two applications of the high rate of fluopyram + prothioconazole. Two applications of the high rate of fluazinam had the lowest AUDPC, which was nearly 60% lower than the untreated control. Two applications of the high rate of thiophanate-methyl was the highest yielding treatment, recovering 70% of yield lost from untreated plots. Economic impacts varied with planting dates. For the first planting, profit margins for all fungicide treatments, with the exception of two applications of penthiopyrad, two applications of the low rate of fluxapyroxad + pyraclostrobin, and the biofungicide seed treatment, were significantly greater than the untreated control. For the second planting, only profit margins for all fluazinam treatments were significantly greater than the untreated control. This study identifies new economically viable fungicide options for dry bean producers to control white mold.     

Income and labour productivity of collection and use of indigenous fruit tree products in Zimbabwe

Rural people in Africa periodically rely on wild fruits to supplement their diet and to generate cash income. However, scientific evidence on the economics of using indigenous fruit tree (IFT) products is scarce. The objective of the study was to fill in some of the gaps for which farm-household surveys were conducted in Zimbabwe during 1999–2000. Gross margins and returns to labour in collection, use and sale of products of Uapaca kirkiana (Muell. Arg., Wild Loquat), Strychnos sp. (S. cocculoides (Baker) and S. spinosa (Lam.), Monkey Orange) and Parinari curatellifolia (Planch. ex. Benth., Fever Tree) were compared with other farming activities. A random sample of over three hundred households in the Murehwa Communal and the Takawira Resettlement Areas was interviewed to gather income and expenditure data. Additionally, income, expenditure and labour allocation of 39 households were closely monitored for one year. Results indicated that the majority of rural households benefited from consumption and sale of indigenous (IF), although the extent varied among households. Within the households, children were the main consumers of fruits. Marketing of IF are carried out by women who used the receipts to purchase household goods. While U. kirkiana fruits were more important in generating cash income than others, fruits of P. curatellifoliawere important for home consumption during periods of food shortages. The gross margins for collection of IFT products were lower than for livestock and crop production. However, returns to labour from collection and use of IFT products were considerably greater than from other activities including gardening and livestock rearing. The study indicates that collection of IFT products is an efficient labour allocation strategy in Zimbabwe. This revised version was published online in June 2006 with corrections to the Cover Date.     

The influence of land-use practices and economics on plant species richness in meadows

Thirty-one meadows were investigated within five sites representing various farming styles found in Austrian cultural landscapes. The meadows were analysed regarding (a) biodiversity (vascular plant and bryophyte species richness), (b) land-use practices (fertiliser input, mowing intensity, the use of silage), and (c) economic aspects (variable costs, profit margin and subsidies per ha). There were significant negative correlations between plant species richness and mowing intensity and intensity of fertiliser application. Bryophytes were good indicators of low nutrient regimes, having high species richness at low fertiliser input. Vascular plants showed highest species richness at an intermediate nitrogen supply. The total plant species richness decreased with increasing nitrogen supply. Intensive silage production was also negatively correlated with plant diversity. Species with a very narrow ecological niche of soil moisture and nutrients declined, whereas species adapted to wider ecological conditions increased. Profit margin and variable costs correlated negatively with plant species richness, with meadows that offered low or no profit margins showing highest species richness. There was no significant relationship between species richness and the amount of subsidies invested at the study meadows. Estimated costs of maintaining a species are shown. It is concluded that if plant species richness are to be maintained in these meadows, farmers have to receive increased financial incentives through agro-environmental subsidies for appropriate meadow management, and these have to be linked to clearly defined measures.     

云南主要地方牛种横纹肌组织形态学研究

采用组织学、电镜方法对云南主要地方牛种大额牛、云南瘤牛、中甸牦牛、迪庆黄牛和中甸牛扁牛的肌纤维特性作了系统研究。５个牛种背最长肌的肌纤维直径（μｍ）分别为５７．４８±１．１５、１０９．４５±１．８４、１００．３８±６．２５、９０．３８±５．３１和９７．３５±９．６２;肌纤维密度（根／ｍｍ２）分别为２０１．５４±２．６６、１１５．４５±４．０４、１０６．３０±１０．１０、９０．３８±５．３１和９２．３５±９．６２;肌束内纤维数（根）分别为７３．２３±８．９０、３４．３２±８．７７、３６．３２±８．３０、４７．６２±８．９０和４０．４０±８．７９。肌节长度（μｍ）以大额牛公牛最长（１．７０６５）,云南瘤牛去势公牛居中（１．４６７０）,云南瘤牛公牛最短（１．２０５０）。