Quality versus quantity: spring wheat seed size and seeding rate effects on Avena fatua interference, economic returns and economic thresholds

A 3-year field experiment was conducted at Kalispell, Montana, USA, to investigate the effects of spring wheat seed size and seeding rate on wheat yield loss (YL), economic returns and economic thresholds (ETs), as a function of Avena fatua density. Crop competitive ability increased as wheat seeding rate and seed size increased, with the greatest differences among treatment factors being observed at low weed densities. Both treatment factors decreased spring wheat YL, increasing economic returns during all 3 years of the study despite the higher associated seed costs. Averaged over all other factors, adjusted gross returns (AGR) were 477 and 537$ ha⁻¹ for the low and high seeding rates, while values of 453, 521 and 547$ ha⁻¹ were obtained for the small, bulk and large seed size classes respectively. Weed-free yield potential varied yearly. As yield potential increased, A. fatua competitive effects were more evident and ETs decreased. Nonetheless, both treatment factors increased ETs in 2 of 3 years. These results demonstrate that the use of higher seeding rates and larger seed size classes both improve wheat competitive ability towards A. fatua while simultaneously increasing economic returns.     

Weed Detection Using Canopy Reflection

For site-specific application of herbicides, automatic detection and evaluation of weeds is desirable. Since reflectance of crop, weeds and soil differs in the visual and near infrared wavelengths, there is potential for using reflection measurements at different wavelengths to distinguish between them. Reflectance spectra of crop and weed canopies were used to evaluate the possibilities of weed detection with reflection measurements in laboratory circumstances. Sugarbeet and maize and 7 weed species were included in the measurements. Classification into crop and weeds was possible in laboratory tests, using a limited number of wavelength band ratios. Crop and weed spectra could be separated with more than 97% correct classification. Field measurements of crop and weed reflection were conducted for testing spectral weed detection. Canopy reflection was measured with a line spectrograph in the wavelength range from 480 to 820 nm (visual to near infrared) with ambient light. The discriminant model uses a limited number of narrow wavelength bands. Over 90% of crop and weed spectra can be identified correctly, when the discriminant model is specific to the prevailing light conditions.     

乙氧氟草醚、乙草胺和盖草能在苗圃中的应用

为了探讨乙氧氟草醚、乙草胺和盖草能在森林苗圃中的应用效果,进行马尾松Pinusmassoniana、火力楠Micheliamacclurei和乳源木莲Manglietiayuyuanensis苗圃化学除草正交试验。试验结果表明,乙氧氟草醚和乙草胺在苗圃播种后芽前期使用和苗期使用乙氧氟草醚、乙草胺和盖草能除草率达90%以上,持效期45～63d,同时对种子发芽出苗和苗木生长安全。采用20%乙氧氟草醚、90%乙草胺和10 8%盖草能,使用剂量为0 105mL·m-2进行化学除草,比人工除草减少除草用工59 1%～66 7%,降低除草成本46 8%～62 9%。表3参4     

串珠藁本分布与危害的调查研究

实地访问、调查表明，串珠藁本（ＬｉｇｕｓｔｉｃｕｍｍｏｎｉｌｉｆｏｒｍｅＰｅｎｇＺＸｅｔＺｈａｎｇＢＹ，ｓｐ．ｎｏｖ．）广布于甘肃南部与青海东部海拔２２００ｍ以上的高寒阴湿区，随海拔的升高，其发生危害也越重。在各类杂草中串珠藁本占６１．０％～９８．０％．还发现前茬是蚕豆、油菜的小麦田发生较轻，前茬是小麦、青稞的蚕豆、油菜田发生则较重。田间试验表明，串珠蒿本密度与小麦产量呈显著负相关，当每公顷密度由０增至９００万株时，小麦每公顷减产由０增至８５２．０ｋｇ．     

The Economic Impact of Site-Specific Weed Control

In order to evaluate economic and ecological benefits, site-specific weed control was realised in a 4-year experiment on five fields with a GPS-guided sprayer. An average of 54% of the herbicides could be saved. Savings were strongly dependent on crop and year. For grass weed herbicides, the savings were 90% in winter cereals, 78% in maize, and 36% in sugar beet. For herbicides against broadleaf weeds, 60% were saved in winter cereals, 11% in maize, and 41% in sugar beet. The monetary savings resulting from the reduction in herbicide use varied between the crops, depending on the amount of herbicides saved and the price of the herbicides. In maize, savings of 42euro/ha were realised, in winter wheat of 32euro/ha, in winter barley of 27euro/ha and in sugar beet of 20euro/ha. Large sections of the fields needed herbicide treatment significantly less frequently. In those areas where weed density remained below the weed control threshold, flora and fauna were allowed to establish largely without disturbance.     

外来生物灾害应急管理系统设计与实现

根据应急管理,构建了外来生物灾害应急管理平台的总体架构,分析了外来生物灾害应急管理的信息结构,采用C++作为开发语言,设计实现了外来生物灾害应急管理系统平台,为外来生物灾害应急管理提供辅助决策服务。     

云南省玉米地杂草发生危害及防治初步研究

 通过1997,1998年的田间调查,结果表明在云南2年5熟地区玉米地杂草有21科,61种。与10年前结果相比,杂草的种类没有明显变化,但杂草优势种发生明显变化,杂草对玉米危害造成的损失减少。危害以一年生杂草为主,其中马唐、旱稗、牛膝菊、胜红蓟、苦荞麦为主要优势种。防除玉米地杂草的除草剂以阿宝桶混剂(30%莠去津SC+25%宝成DF),50%都阿合剂SC,40%乙莠水SC,72%都尔EC,40%莠去津SC,25%宝成DF等较好。     

甘蔗引进亲本创新利用及育种潜力分析

选用24个不同时期从国外引进的甘蔗亲本与国内品种杂交,选配组合45个,研究了引进种有性杂交世代主要性状的遗传效应。结果表明,父本、母本及选配组合对后代的影响存在较大差异;对主要性状遗传力贡献的大小为组合(64.2%)>母本(57.5%)>父本(26.8%);后代主要性状的遗传力大小顺序为株高>有效茎>锤度>糖产量>蔗产量>茎径;24个引进亲本中,CP80-1827、L75-20、P indar、POJ2878和CP57-614等作为母本,CP84-1198、HOCP93-750、CP86-1633、CP72-359和CP57-614等作为父本后代糖产量、蔗产量或锤度的一般配合力大,可分别作为高产或高糖母本和父本加以利用;桂糖92-66×HOCP93-750、CP80-1827×梁河78-85、L75-20×ROC22、CP57-614×云蔗89-7、崖城93-26×HOCP95-988和云蔗94-343×CP72-1210等组合后代蔗、糖产量及锤度表现佳,特殊配合力(SCA)强。     

防除甜菜田禾本科杂草试验

杂草和甜菜争夺营养、水分和阳光,影响甜菜生长。在杂草发生严重的地块,可造成甜菜严重减产。为了探讨化学除草剂对甜菜田禾本科杂草的防效,以掌握其适宜的用量、防除效果及对甜菜的安全性。通过对比试验,结果表明：大庆地区防除甜菜田禾本科杂草,施用10.8%盖草能乳油效果最好。