2011／12年度全球棉花市场形势分析及展望

2011／12年度全球棉花收获面积增长,产量再次超过2700万t。受经济恢复迟缓等影响,同期棉花消费不足2300万t。国际棉花市场供过于求,期末库存继续增加,库存消费比达到67．4％的历史高点。受全球棉花供求关系和中国棉花临时收储政策等因素影响,国际棉花价格持续下跌,国内棉价相对稳定,国内外价差拉大。全球棉花进出口贸易加大,中国棉花进口激增。展望2012／13年度,预计全球棉花植棉面积产量下降,消费状况有所好转,但仍产大于需,库存持续增加,在基本面不变的情况下,未来国际棉价仍将保持弱势震荡格局。     

不同时间尺度太阳辐射数据对作物生长模型的影响(英)

逐日太阳辐射数据是作物模拟模型的重要输入参数之一。然而,在很多情况下,候、旬、月尺度的辐射信息相对容易获取。该文利用长时间序列(1961-2000)逐日太阳辐射数据,分别建立研究区候、旬、月不同时间尺度太阳辐射数据库,利用两个常用的作物生长模型(CERES-Maize和CGOPGRO-Soybean),以逐日数据(太阳辐射和模拟结果)为基准,分别探讨在雨养和灌溉条件下,不同时间尺度太阳辐射数据对作物生长模型的影响。结果表明:在不同时间尺度下,模型的输出(花期和作物产量)都接近于基准值。总体来看,两个模型模拟的花期平均误差和平均相对误差均接近于0,均方根误差为3.5d;CERES-Maize模型的模拟产量低于基准值,而CGOPGRO-Soybean的模拟结果高于基准值。在雨养和灌溉条件下,CERES-Maize的平均相对误差和均方根误差分别为-0.59%,120kg/hm2和-0.52%,129kg/hm2,CGOPGRO-Soybean的平均相对误差和均方根误差分别为5%,152kg/hm2和4.7%,165kg/hm2。短期数据误差(RMSE)是影响模型精度的主要因素。CGOPGRO-Soybean模型对不同时间尺度太阳辐射数据和水情信息比CERES-Maize模型敏感。当缺少逐日太阳辐射数据时,在雨养和灌溉条件下,候、旬、月尺度的太阳辐射数据都可以用于作物生长模型。     

基于面向服务架构和WebGIS的小麦生产管理支持系统

作物模型与GIS集成中存在着功能重复开发、模型共享困难以及地理信息处理功能的在线能力有限等问题。该文以面向服务架构(service-oriented architecture,SOA)为基础,设计了作物模型区域应用Web服务组合框架。以ArcGIS Service和Model Builder为开发平台,给出了模型计算、动态专题图和空间插值Web服务的开发流程、接口设计和实现方法。结合富客户端技术研制了基于SOA和WebGIS的小麦生产管理支持系统原型(wheat production management support system based on SOA and WebGIS,WPMSS-GISOA),实现了地图数据的上传发布、气象和土壤数据查询、栽培方案设计、空间插值分析等功能。功能测试表明作物模型区域应用的Web服务组合框架可行,为模型与地理信息系统的在线无缝集成提供了可参考方案。     

县域水稻抛栽精确定量栽培决策支持系统研究与开发

为了促进抛栽水稻精确定量栽培技术生产应用,通过资料收集、决策模型构建与程序设计等,以姜堰市为例,基于Visual Basic 6.0和MapObjects 2.3,研究与开发了县域水稻抛栽精确定量栽培决策支持系统V1.0。结果表明,该系统涵盖了电子地图导航、基础数据查询、决策支持、知识园地、辅助工具和系统帮助等内容,实现了预期目标;系统界面友好、操作简便、功能全面、应用性强。经试用,系统的可用性、可靠性、易用性较强,用户满意度较高,可作为生产上推广应用水稻抛栽精确定量栽培技术的信息化优质辅助平台。     

基于主成分分析的支持向量机需水预测模型及其应用

需水预测是水资源优化配置、水资源规划和水资源管理的重要依据,其预测精度受到众多因素的影响,且实际用水量数据时间系列较短,制约了传统预测方法的应用。利用支持向量机在对小样本学习的基础上对其他样本进行快速、准确的拟合预测的特点,采用主成分分析与支持向量机相结合的方法,首先利用主成分分析法筛选需水量的主要影响因子,然后将其作为输入样本,对支持向量机模型进行训练和检验,寻找最优模型,并将该方法应用于洛阳市需水预测。结果表明,该模型预测结果平均相对误差为-0.83%,预测精度较高,可作为训练样本较少情况下的一种需水预测方法。     

基于资源环境水价的塔里木河流域作物农业水价的节水效应分析

立足当前塔河流域的成本水价,基于已有研究的流域水资源费和环境水价模型与相关资料,首先构建了流域基于资源环境水价的未来农业水价;然后,利用已有研究资料和流域不同作物的水分生产函数,进一步构建了流域未来作物农业水价的需求效应模型;分析了未来塔河流域基于资源环境水价的未来作物农业水价的节水效应。结果表明:基于资源环境水价的未来农业水价调整可大幅提高节水效应,只是环境水价更侧重于实现流域生态用水保障的经济补偿。再者,不同流域和作物水价需求弹性效应差别很大,可以实行有差别的农业水价调整政策。还有,流域水价弹性系数会由缺乏弹性变为富有弹性,受作物基本灌溉定额限制,就是采用高效节水技术也难以保证水价节水效应的实现,这成为流域农业水价调整可行性的一个标志。但是,这也使未来流域农业水价的需求效应分析事关流域粮食安全和用水户的水价承受力问题,成为未来塔河流域农业水价调整研究的重要相关研究内容。     

A DEMAND ANALYSIS FOR CRUSTACEANS AT THE U.S. RETAIL STORE LEVEL

This study used a LA/AIDS model to estimate demand system for crustacean species, shrimp, crab, crawfish and lobster at the U.S. retail store level. Shrimp demand is price elastic; crab, crawfish and lobster are price inelastic. Shrimp price significantly affects market shares of crustacean products. Shrimp has more substitutes than other crustaceans, and lobster has less substitutes than others. The demand for crab and lobster grow faster than the demand for shrimp and crawfish when expenditure increases. Promotion has positive effects on market shares and sales volume of own products and negative effects on cross-products. Shrimp price-reduction promotion strategies will be effective in term of raising shrimp sales value. Marketing programs that increase consumers’ marginal utility with an additional small increase in the selling price of crab, crawfish and lobster products will be feasible, and bring higher sale values.     

Performance of shrimp futures markets as price discovery and hedging mechanisms

Abstract

Granger causality tests revealed leading indicators of shrimp futures prices, implying that futures prices do not reflect all available market information and potentially fail to be an exemplary price discovery mechanism. Trading simulations confirmed that the use of some leading indicators allowed profitable arbitrage in shrimp futures trading. Shrimp futures were deficient as a hedging tool, as well. Correlations between futures and wholesale cash prices were often low, and basis risk rivaled price risk. Lack of liquidity is a likely explanation for shrimp futures’ shortcomings as a hedging tool and price discovery mechanism.     

Behaviour of price transmissions in vertically coordinated markets: The case of frozen black tiger shrimp (Penaeus monodon)*

Abstract

This study analyses the behaviour of the price transmission process for the leading cultured shrimp species, black tiger shrimp (Penaeus monodon), in both forward and backward directions between Thai and Indonesian shrimp packer markets and the Japan Tokyo wholesale market. The bivariate cointegration approach using the Engle‐Granger two‐stage estimation procedure is applied in this study. The results show that Tokyo wholesale prices appear to have stronger backward influences on the formation of overseas contract prices used by Japanese shrimp importers in the Thai and Indonesian shrimp packer markets. In addition, there is a tendency for the speed of price transmissions in the long term to increase with increasing size class (from 26 to 30–21–25 and 16–20 counts per pound) of black tiger shrimp, regardless of estimation specification in the direction of price transmissions and the shrimp country of origin.     

Economic analysis of alternative protein levels in channel catfish feeds

Abstract

Nutritional requirements for catfish (Ictalurus punctatus) feeds based solely on maximizing growth may not lead to the best economic performance. In addition, the choice of protein level may have important implications for dress‐out percentages in the processing sector. Processors may be able to send pricing signals to farmers to improve processing efficiencies. The objectives of this paper are to quantify the economic incentives to use different protein levels in catfish feeds and to investigate the possibility of processor incentives to affect these decisions. Data from research ponds, in conjunction with pricing and cost data, were used to quantify the changes in net returns associated with alternative protein levels. Both experimental results and estimates using commercial practices were developed. In addition these data were utilized in developing price premiums that might be implemented by the processing sector to provide incentives that would result in higher dress‐out percentages and thus greater processing efficiency. In a restricted‐feeding regime, selection of the higher protein feeds resulted in higher net returns, however, in a satiation‐feeding regime, lower protein levels resulted in higher net returns. Specifically, catfish enterprise profitability could be enhanced by feeding a 38% protein ration when fish are fed on a restricted basis whereas, in a satiation‐feeding regime profitability could be enhanced by feeding a 26% protein ration. Results indicate that the potential for a price premium policy that encourages a higher dress‐out percentage might be adopted in the future by the’ catfish processing sector as has been done in other meat processing industries.