Analysis on Function Orientation and Development Countermeasures of New Agricultural Business Entities

Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural modernization in China. The status of the new agricultural business entities determines the level of modern agricultural development. In recent years, new agricultural business entities have grew rapidly. However, there are still many problems including the difficulties in financing loans, inadequate agricultural insurance system, bad implementation of agricultural subsidies, jagged agricultural talents and so on. In order to foster new agricultural business entities, countermeasures should be carried out to ensure financial support, perfect the agricultural insurance, strengthen the level of agricultural subsidies, strive to develop the degree of specialization agricultural operators and so on.     

Optimizing continuous cover management of boreal forest when timber prices and tree growth are stochastic

Background: Decisions on forest management are made under risk and uncertainty because the stand development cannot be predicted exactly and future timber prices are unknown. Deterministic calculations may lead to biased advice on optimal forest management. The study optimized continuous cover management of boreal forest in a situation where tree growth, regeneration, and timber prices include uncertainty.Methods: Both anticipatory and adaptive optimization approaches were used. The adaptive approach optimized the reservation price function instead of fixed cutting years. The future prices of different timber assortments were described by cross-correlated auto-regressive models. The high variation around ingrowth model was simulated using a model that describes the cross- and autocorrelations of the regeneration results of different species and years. Tree growth was predicted with individual tree models, the predictions of which were adjusted on the basis of a climate-induced growth trend, which was stochastic. Residuals of the deterministic diameter growth model were also simulated. They consisted of random tree factors and cross- and autocorrelated temporal terms.Results: Of the analyzed factors, timber price caused most uncertainty in the calculation of the net present value of a certain management schedule. Ingrowth and climate trend were less significant sources of risk and uncertainty than tree growth. Stochastic anticipatory optimization led to more diverse post-cutting stand structures than obtained in deterministic optimization. Cutting interval was shorter when risk and uncertainty were included in the analyses.Conclusions: Adaptive optimization and management led to 6%–14% higher net present values than obtained in management that was based on anticipatory optimization. Increasing risk aversion of the forest landowner led to earlier cuttings in a mature stand. The effect of risk attitude on optimization results was small.     

About Agricultural Science & Technology

<正>In China,Agricultural ScienceTechnology is the first comprehensive agricultural English journal.The editor-in-chief is YUAN Long-ping,and the editorial board members are CHEN Wen-xin,FANG Zhi-yuan,GUAN Chun-yun,WU Chang-xin,WU Ming-zhu and YUAN Long-ping,who are academicians of Chinese Academy of Sciences or Chinese Academy of Engineering.The journal(CN43-1422/S;ISSN 1009-4229),sponsored by Hunan Academy of Agricultural Sciences,aims to enhance international influence of China's agricultural scientific research.It has a good reputation in the world,and for exchange of information,the journal has long-term,stable     

Classification of Tomicus Species

Both morphological characters and a portion of of 28S rDNA sequences were used to identifying Tomicus species.The specimens were classed into groups with the following characters: 1) granules or punctures on interstria 2 on the declivity of the elytra;2) length of the elytral interstrial hairs and hairs arising from punctures;3) arrangement of pronotal punctures and hairs.These characters could be clearly examined under a binocular microscope at 30×magnification and they were applicable and valuable for the forest entomologists to identify Tomicus species.The phylogenetic tree established with difference in 28S rDNA sequence of D2 region revealed that the specimens of each group identified by morphological characters were also grouped together.The genetic distances of intra-species, inter-species and inter-genus were not overlapped. Genetic divergence of 28S rDNA was also useful for identifying Tomicus species.     

Key rock strata effecting analysis on surface boreholeshear deformation fracture

A good method for creating a surface borehole for withdrawing coal strata methane is to build before excavation and use during the whole process. But the excavation greatly affects the overlying rock strata, and when the excavation face passes through the     

不同农业管理措施对土壤线虫的影响

研究了不同农业管理措施对土壤线虫的影响,结果表明:日光温室中土壤线虫的优势种群为食细菌的小杆线虫(Rhabditis),常规农田中优势种群为食细菌的小杆线虫和植食性的螺旋线虫(Helicotylenchus),休闲地中优势种群为植食性线虫,包括螺旋线虫、盘旋线虫(Rotylenchus)和丝尾垫刃线虫(Filenchus);线虫的多样性、丰富度、ΣMI、EI、SI指数表明日光温室所受到土壤线虫的扰动最强,常规农田次之,休闲地所受干扰最小;PPI/MI、WI、BI、CI指数表明日光温室土壤营养丰富,常规农田和休闲地营养贫瘠.     

An Empirical Study on the Relationship Between China's Maize Price and Maize Import and Export Trade

Based on the time series of China’s maize trade and domestic maize price,the article analyzes the relationship between domestic maize price and China’s maize international trade by using empirical methods.The results show that there is a connection between domestic maize prices and China's maize international trade,but the link is not very close.Domestic maize price is the cause of China’s maize international trade change,but its impact is very limited;China's maize international trade also can make some difference on the domestic maize price.Based on the results of research,the article brings three suggestion and expectation to adjust China’s maize international trade and the cost control reasonably in order to stabilize domestic maize price and maize yield,and to protect domestic grain security.     

农用抗生素分离纯化的研究进展

目前我国农用抗生素大规模生产的品种主要有井冈霉素、阿维菌素和赤霉素,而未能大规模生产的抗生素共同存在的问题是技术不成熟,生产成本较高,进而限制了其在生产实践中的应用;另外我国农用抗生素研究的人力、物力过于分散.对一些优良品种投入太少,也是造成大规模生产的农用抗生素品种少的主要因素.阐述了国内外农用抗生素有效成分分离、提取、纯化技术特点与发展趋势.     

推广农业标准化生产 加速农业现代化进程——记粮油作物易学易用栽培技术示范项目主要做法与基本经验

本文通过粮油作物易学易用栽培技术示范项目的实施,为全区农业现场会顺利召开创造了条件,奠定了基础.系统总结出项目实施过程中取得的主要成效、做法与基本经验.