基于地块单元的冬小麦遥感估产方法研究

[目的]以高分时序遥感影像为基础数据源,结合土地承包经营权地块数据,对冬小麦遥感估产方法及其精度进行研究和分析。[方法]文章以河南省兰考县为研究区,采用2019年4―5月份的GF-1C和GF-6 2 m PMS遥感影像提取了研究区冬小麦种植空间分布,并在地块单元控制下对冬小麦种植面积进行了修正和精度验证。其最优提取结果的修正阈值为0.93,地块单元内冬小麦总体分类精度为95.66%,Kappa系数为0.89。利用3月7日至5月20日6期GF-1 WFV遥感影像序列NDVI和RVI与冬小麦种植地块单元数据进行空间统计,得出各冬小麦种植地块单元内NDVI和RVI均值,通过分析冬小麦测产地块单元内均值植被指数与产量间的敏感性,提出一种组合均值植被指数的冬小麦遥感估产模型构建方法,通过交叉验证法对不同的估产线性回归模型进行精度评价。[结果]由4个均值植被指数组合变量的多元线性回归模型为最佳,决定系数为0.922 0,预测误差为40.96 g/m~2,预测精度为93.13%。通过该模型得出兰考县冬小麦平均产量为6 047.25 kg/hm~2,较2017年河南省统计年鉴研究区冬小麦平均单产6 001 kg/hm~2有所提高,土地承包经营权地块内和地块外冬小麦总产量分别为2.76亿kg和4 650万kg。[结论]该方法实现了冬小麦估产结果以像元为单位向以地块单元为单位的转变,解决了模型构建时光谱信息与实测产量间对应问题,为利用国产高分卫星进行县域地块尺度遥感单产精准化估算提供了方法支撑。     

小麦赤霉病及控制技术研究进展

赤霉病作为小麦常见病症的一种,近年来发生的越来越频繁。本文简述小麦赤霉病发生的性状、影响因素、处理手段,为赤霉病小麦的处理方法提供一些参考。     

利用生物酶解技术提高小麦麸皮食用性的研究

麸皮是小麦制粉的主要副产物,占小麦质量的15%~20%,我国每年约有2000万t小麦麸皮资源,85%以上用于饲料、传统酿造业,资源增值转化率低。小麦麸皮中含有丰富的膳食纤维、蛋白质、植酸、维生素、矿物质等。本课题采用纤维素酶、半纤维素酶和木聚糖酶对小麦麸皮进行酶解,通过实验确定了纤维素酶、半纤维素酶和木聚糖酶联合酶解麸皮最适条件,即60℃,PH为4,酶解时间为4hr,料水比为1:15,酶比为5:10:2,或者在60℃,PH为5,酶解时间为3hr,料水比为1:10,酶比为5:10:3,在此条件下,酶解后的小麦麸皮食用性最佳。     

小麦面筋含量测定影响因素分析

面筋含量是影响小麦和小麦粉品质的重要因素,面筋吸水率是小麦储存品质的重要指标。本文对小麦面筋含量测定中的关键步骤和重点环节进行了分析,探讨不同因素对试验结果造成的影响及应注意的事项,以期为各基层试验人员提供借鉴,为未来标准的修订提供参考。     

基础设施在中国农业全要素生产率中的作用

This paper uses the Malmquist index to examine the sources of Total Factor Productivity (TFP) in Chinese agriculture. The overall goal of this study is to create a framework for assessing the trend of China’s agricultural infrastructure and to measure its impact on Total Factor Productivity. The main methodological contribution is to provide more contributive measure of crop-specific technologies. Based on the province-level panel data set during 1988–2002, the primary finding is that infrastructure has positively and statistically significant association with the estimated coefficient on Total Factor Productivity for rice, wheat, maize, and bean. An erratum to this article is available at .     

Cash Marketing Styles and Performance Persistence

Much agricultural economics research has been dedicated to determining the best time for producers to sell their commodities. Unlike this past research, we look at how producers actually sell commodities. The extent to which producers display an active or mechanical marketing style is measured using individual farmer sales. The activeness of a producer's marketing strategy is measured by how much the timing of their strategy varies from year to year. Results show no relationship between activeness and net prices received. Furthermore, the results show no evidence of performance persistence by individual producers.     

The Tunisia Wheat Market in the Context of World Price Volatility: A Stochastic Partial Equilibrium Approach

Food security is a key objective of agricultural and food policy in Tunisia. The 2007–2008 food crisis highlighted the negative impacts of price volatility on international markets both in terms of food insecurity and budget exposure. Tunisian food subsidy expenditures ranged from $180 million to $710 million in 2006–2010, so volatile world prices meant volatile subsidy costs. Moreover, cereal production in Tunisia still has much instability due to climate conditions, which also influences imports and, consequently, subsidy expenditures. This study applies a structural model to conduct stochastic analyses of trade and policy impacts on food security and budget expenditures in the Tunisian wheat market. The methodology disaggregates durum wheat and soft wheat markets and generates projections of import prices of durum wheat and soft wheat, using projections of world prices provided by the Food and Agricultural Policy Research Institute at University of Missouri (FAPRI-MU). The key innovation is the generated stochastic analyses of subsidy costs based on stochastic world price projections and stochastic domestic wheat yields based on historic yield variances. The analysis highlights the sensitivity of subsidy costs to world prices, volumes imported and domestic production, so that alternative policy tools can be considered.