The feasibility of using variable rate water application under a central pivot irrigation system

The purpose of this paper was to assess the feasibility and significance of applying spatially variable irrigation under a central pivot system at the Federal German Agricultural Research Center, Braunschweig, Germany. The assessment was based on soil moisture holding capacity, soil depth variation and root development. Soil texture analysis was carried out by sampling on a 60 meter grid. The German Agro-Meteorological Model was applied to simulate the water balance in the crop-soil-atmosphere system for the growing season 2003/4. The research findings are presented in terms of six scenarios: 20, 30, 40 mm water application depths per irrigation under both variable rate application and uniform application. The comparison revealed that the loss of water was higher for the uniform application scenarios than that for the variable rate application (VRA) scenarios for the applications of 20 and 30 mm. The VRA scenario of 20 mm water application was found out to be the best option for water conservation.     

基于对象建模的农机产品CAPP系统设计与应用

利用对象建模技术,通过抽象与重组形成CAPP系统的一般对象模型,并把对象、关联及操作等映射成数据库表和程序实体,结合农机产品CAPP实例论述了工艺过程卡对象模型的实现流程,分析了选单等的设计重用方法。实践证明,CAPP系统开发过程中,只需开发一个编辑窗口,而非对应每一个数据表开发相应的编辑窗口。当数据表发生结构改变时可通过修改数据窗口来实现。采用这种方法,同一个选单就可以被不同的窗口所共用,使系统的开发效率大大提高,同时系统的结构也非常合理,根据作业机的主体结构相似性,可应用于各类农机制造的工艺设计过程。     

稻瘟病抗病基因定位及克隆研究进展

稻瘟病是水稻生产中最严重的真菌病害,严重影响着水稻的产量。随着DNA分子标记的不断发展及水稻基因组测序的完成,稻瘟病抗病基因的定位克隆取得了突破性的进展,为稻瘟病抗病机理研究以及稻瘟病抗性育种奠定了重要基础。本文综述了稻瘟病抗病基因定位及克隆的研究进展,对稻瘟病抗病基因的研究成果在实践中的应用提出了展望。     

小麦7D染色体数量性状基因定位和效应估计的研究

综合应用方差分析法、区间定位法和联合定位法将控制抽穗期、有效穗数、小穗数、５０粒重和单穗产量等５个性状的６个数量性状基因座（ＱＴＬ）定位在小麦７Ｄ染色体上。其中控制粒重的ＱＴＬ有２个。这些ＱＴＬ集中分布在着丝粒附近和染色体长臂的末端两个区域。效应估计结果表明多数ＱＴＬ的效应是微效的，控制同一个性状（粒重）的两个ＱＴＬ的效应几乎相等。比较３种ＱＴＬ定位法的分析结果，方差分析简单有效，且当染色体上只有     

利用已测序水稻品种分析其农艺性状基因座

水稻重要农艺性状的基因定位研究在育种上具有重要意义。2004年在海南陵水县种植两个完全测序水稻品种日本晴与9311的F₂群体及双亲，分别考察了其单株分蘖数、穗数、有效分蘖数、穗长、主穗长、抽穗期、株高和剑叶8个农艺性状3次重复的平均值。用已构建的连锁遗传图谱（Nipponbare/9311-F₂遗传图谱）及Excel 2000和Mapmaker/QTL 1.1b软件对这8个性状间的相互关系和基因位点进行了分析。结果在LOD>2.0和P＜0.005的条件下共检测到41个QTLs，它们分布在水稻所有染色体上，单个QTL对性状表型贡献率11.0%～46.4%，其中大于20%的有22个。对选用已测序材料为亲本构建图谱来探讨水稻农艺性状的分子基础及其育种意义进行了讨论。     

Enhancing the Simplified Surface Energy Balance (SSEB) approach for estimating landscape ET: Validation with the METRIC model

Evapotranspiration (ET) can be derived from satellite data using surface energy balance principles. METRIC (Mapping EvapoTranspiration at high Resolution with Internalized Calibration) is one of the most widely used models available in the literature to estimate ET from satellite imagery. The Simplified Surface Energy Balance (SSEB) model is much easier and less expensive to implement. The main purpose of this research was to present an enhanced version of the Simplified Surface Energy Balance (SSEB) model and to evaluate its performance using the established METRIC model. In this study, SSEB and METRIC ET fractions were compared using 7 Landsat images acquired for south central Idaho during the 2003 growing season. The enhanced SSEB model compared well with the METRIC model output exhibiting an r² improvement from 0.83 to 0.90 in less complex topography (elevation less than 2000 m) and with an improvement of r² from 0.27 to 0.38 in more complex (mountain) areas with elevation greater than 2000 m. Independent evaluation showed that both models exhibited higher variation in complex topographic regions, although more with SSEB than with METRIC. The higher ET fraction variation in the complex mountainous regions highlighted the difficulty of capturing the radiation and heat transfer physics on steep slopes having variable aspect with the simple index model, and the need to conduct more research. However, the temporal consistency of the results suggests that the SSEB model can be used on a wide range of elevation (more successfully up 2000 m) to detect anomalies in space and time for water resources management and monitoring such as for drought early warning systems in data scarce regions. SSEB has a potential for operational agro-hydrologic applications to estimate ET with inputs of surface temperature, NDVI, DEM and reference ET.     

北方麦区主要小麦品种株高构成指数的非线性映射

利用非线性映射对黄淮冬麦区,北部冬麦区、北部春麦区及西北春麦区,８０年代大面积推广的４１个小麦品种株高构成指数的地理差异进行了研究,结果表明,这些主要推广品种绝大多数为中产或中高产类型,麦区间小麦品种株高构成指数未见明显差异。     

A-3中抗条锈新基因YrTp1和YrTp2的分子标记定位分析

【目的】半个多世纪的中国小麦育种史基本是育种家与条锈病的赛跑史。因此，筛选、鉴定、储备和利用新抗源是我国育种和资源研究中的一个长远战略性课题。【方法】利用小麦条锈菌条中31、32号生理小种，对来自小麦与十倍体长穗偃麦草［Thinopyrum ponticum (Host) Liu & Wang］的杂交后代材料A-3进行抗性遗传分析。用荧光SSR分子标记技术，鉴定所携带抗条锈病基因是否为新基因，并对其进行染色体定位研究。【结果】遗传分析表明，A-3对条中31号和32号的抗性由一显一隐2对基因控制。经过对196对微卫星引物的筛选，发现2B染色体短臂上的WMC477-167bp与显性基因紧密连锁，遗传距离为0.4 cM,将该显性基因定位于2BS上；7B染色体短臂上的WMC364-208bp与隐性基因连锁，遗传距离为5.8 cM。图位比较、系谱分析和抗谱分析表明，A-3所含抗条锈基因不同于已知抗条锈基因，暂定名为YrTp1和YrTp2。【结论】可利用A-3中与条锈病抗性紧密连锁的分子标记YrTp1和YrTp2将抗性基因转移到主栽品种中，在小麦育种和生产上发挥作用。     

水稻产量性状定位与基因克隆研究进展

文中主要从性状定位和基因克隆方面对产量构成三因子,即分蘖、穗粒数和粒重的研究成果进行了综述,并同时详细阐述了影响产量的其他因素,包括株高和杂种优势等的研究进展,并在最后就影响单株产量的分子基础、激素与产量的关系、水稻产量性状的定位策略3个方面对这些研究成果进行了总结和讨论。