The effects of seed mix and management on the abundance of desirable and pernicious unsown species in arable buffer strip communities

Buffer strips are refuges for a variety of plants providing resources, such as pollen, nectar and seeds, for higher trophic levels, including invertebrates, mammals and birds. Margins can also harbour plant species that are potentially injurious to the adjacent arable crop (undesirable species). Sowing perennial species in non‐cropped buffer strips can reduce weed incidence, but limits the abundance of annuals with the potential to support wider biodiversity (desirable species). We investigated the responses of unsown plant species present in buffer strips established with three different seed mixes managed annually with three contrasting management regimes (cutting, sward scarification and selective graminicide). Sward scarification had the strongest influence on the unsown desirable (e.g. Sonchus spp.) and unsown pernicious (e.g. Elytrigia repens) species, and was generally associated with higher cover values of these species. However, abundances of several desirable weed species, in particular Poa annua, were not promoted by scarification. The treatments of cutting and graminicide tended to have negative impacts on the unsown species, except for Cirsium vulgare, which increased with graminicide application. Differences in unsown species cover between seed mixes were minimal, although the grass‐only mix was more susceptible to establishment by C. vulgare and Galium aparine than the two grass and forb mixes. Annual scarification can enable desirable annuals and sown perennials to co‐exist, however, this practice can also promote pernicious species, and so is unlikely to be widely adopted as a management tool in its current form.     

娄底市草坪杂草种类、分布及危害

为探究娄底市草坪杂草种类、分布及危害状况,通过野外调查、查阅植物标本信息和文献资料,应用统计方法分析重要值等指标,确定娄底市草坪常见杂草有68种,隶属28科58属,以菊科、禾本科、伞形科为优势科;一年蓬(Erigeron annuus)、看麦娘(Alopecurus aequalis)、白茅(Imperata cylindrica)等13种杂草为杂草优势种,应列为主要防控对象。本研究为娄底市草坪杂草的防控与综合利用提供了重要资料,也可为其他地区杂草的类似研究参考。     

基于生态位理论的作物—杂草化感作用及其关系探讨

作物－杂草化感作用是作物与杂草之间生态位竞争的重要机理之一。利用作物－杂草化感作用和生态位理论解决实际农业生产中的生态学问题具有重要意义。本研究就作物－杂草化感作用与其生态位的内在联系进行初步探讨,从生态位理论入手,对农作物及其杂草化感作用等个体或微观生态学研究在宏观生态学中的应用进行探讨,并据此进行推导在野外生态环境中强化对杂草具有强化感抑制作用的作物品种的人工选择和合理布局,可以实现杂草的整体防控和宏观生态评价,为下一步“基于生态位理论的作物－杂草化感作用研究”提供理论基础。     

新疆伊犁河谷天然草地毒害草种类分布及防治对策

[目的]了解伊犁河谷天然草地毒害草种类分布,为综合防治提供科学依据.[方法]实地调查与资料相结合.[结果]伊犁河谷天然草地约有毒害草104种,隶属12科,占该地区植物种数的8;;毒害草的分布面积约733 300 hm2,占草地总面积的21.44;.[结论]毒害草蔓延已经成为伊犁河谷草原退化的主要原因之一,成为伊犁草原的隐形杀手,严重制约了草原畜牧业的发展.     

Greenhouse and field evaluations of commonly occurring weed species for their host suitability to Meloidogyne species

Since weeds serve as hosts for nematode pests, the host status of 20 weed species (commonly occurring in fields of developing farmers) to Meloidogyne incognita and M. javanica, respectively, were investigated. Greenhouse studies showed that seven weed species had Rf values >1 for both nematode species indicating susceptibility, while 13 had Rf values ≤ 1 indicating resistance. Greenhouse results showed that Hibiscus trionum and Amaranthus tricolor were identified as the most susceptible and Chenopodium carinatum and Datura ferox the poorest hosts for M. incognita and M. javanica. For field experiments at Kuruman, Solanum retroflexum was the most susceptible weed to a M. javanica population, while the same was evident for H. trionum at Nelspruit, where a mixed population of M. incognita and M. javanica occurred and at Potchefstroom, where a population of M. incognita was present. Results from this study indicated that certain weed species are highly susceptible to root-knot nematodes and should be removed timely and effectively to prevent population level increases of root-knot nematode pests in the fields of farmers.     

Weed flora and seed yield in quinoa crop (Chenopodium quinoa Willd.) as affected by tillage systems and fertilization practices

The effects of tillage system and fertilization regimes on weed flora in quinoa (Chenopodium quinoa Willd.) were evaluated by means of two field experiments in 2011 and 2012. The experiments were laid out in a split-plot design with two main plots (conventional and minimum tillage) and four sub-plots (fertilization regimes). The results indicated that weed biomass and density in quinoa were influenced by the different fertilization and tillage treatments. Moreover, seed yield in conventional was 5%–13% higher than that of minimum tillage, probably due to the lower weed density and biomass. Concerning fertilization treatments, total weed density and biomass increased under manure application and inorganic fertilization. Tillage effects on weeds were species specific. The density of perennial weeds such as purple nutsedge (Cyperus rotundus L.) and the density of small-seeded weeds such as redroot pigweed (Amaranthus retroflexus L.) and common purslane (Portulaca oleracea L.) were significantly lower under the conventional tillage than under the minimum tillage system.     

Benefits of a maize–bean–weeds mixed cropping system in Urubamba Valley,Peruvian Andes

Abstract

In the Urubamba Valley, Peruvian Andes, we evaluated the abundance of insect pests and natural enemies in experimental plots where maize was grown either as monoculture, intercropped with beans, or intercropped with beans plus associated weeds. We also assessed the consequences of the cropping system for maize yield. The main insect pests recorded were Diabrotica spp. (Coleoptera: Chrysomelidae), Carpophilus sp. (Coleoptera: Nitidulidae) and Pagiocerus frontalis (Coleoptera: Scolytidae), and their overall abundance did not differ among crop diversity treatments. However, there was a significant adverse effect of crop diversity on the maximum abundance of both Carpophilus and Pagiocerus. The main beneficial arthropods were Paratriphleps sp. (Hemiptera: Anthocoridae), ladybirds and spiders, and their density did not differ among treatments. Maize yield did not decrease with increasing plant diversity. The reported benefits of intercropping, together with the associated efficiency in land use, make this traditional agricultural practice a valuable alternative to the use of pesticides, particularly for resource-poor Andean farmers.     

The increasing importance of herbicides in worldwide crop production

Herbicide use is increasingly being adopted around the world. Many developing countries (India, China, Bangladesh) are facing shortages of workers to hand weed fields as millions of people move from rural to urban areas. In these countries, herbicides are far cheaper and more readily available than labor for hand weeding. History shows that in industrializing countries in the past, including the United States, Germany, Japan and South Korea, the same phenomenon has occurred—as workers have left agriculture, herbicides have been adopted. It is inevitable that herbicide use will increase in sub‐Saharan Africa, not only because millions of people are leaving rural areas, creating shortages of hand weeders, but also because of the need to increase crop yields. Hand weeding has never been a very efficient method of weed control—often performed too late and not frequently enough. Uncontrolled weeds have been a major cause of low crop yields in sub‐Saharan Africa for a long time. In many parts of the world, herbicides are being increasingly used to replace tillage in order to improve environmental conditions. In comparison with tillage, herbicide use reduces erosion, fuel use, greenhouse gas emissions and nutrient run‐off and conserves water. © 2013 Society of Chemical Industry     

河北省沧州市麦田禾本科杂草发生情况调查

采用随机取点和倒置＂W＂型取样相结合的方法,对河北省沧州市麦田禾本科杂草的发生情况进行了调查。结果表明：沧州市麦田主要禾本科杂草为雀麦和节节麦,但不同县（市）发生情况差别较大。其中,泊头市麦田没有发现禾本科杂草;东光县、河间市和吴桥县麦田均有雀麦发生,相对多度分别为14.1%、14.4%和4.0%,发生程度分别处于第3位、第5位和第5位;吴桥县和东光县麦田均有节节麦发生,相对多度分别为4.4%和2.3%,发生程度分别处于第4位和第9位。     

河北省衡水市麦田禾本科杂草发生情况调查

采用随机取点和倒置＂W＂型取样相结合的方法,对河北省衡水市麦田禾本科杂草的发生情况进行了调查。结果表明：衡水市麦田禾本科杂草主要为雀麦和节节麦。其中,雀麦普遍发生,且在多数地区已经上升为主要杂草,在衡水郊区、景县、深州市和饶阳县的相对多度分别为76.5%、11.9%、45.3%和16.2%;节节麦发生不均,在景县的相对多度为40.2%,是仅次于播娘蒿的第2位主要杂草,在饶阳县节节麦的相对多度为2.7%,在衡水郊区和深州市没有发现节节麦为害。