侧孢短芽胞杆菌在农业中的应用潜力

侧孢短芽胞杆菌Brevibacillus laterosporus具有广泛的生物活性,在农业中具有重要应用价值。本文主要从侧孢短芽胞杆菌在植物病虫害生物防治、促生抗逆、提升土壤肥力及环境微生物修复等方面对侧孢短芽胞杆菌的农用生物活性进行了总结,并对其在农业中大规模应用所存在问题进行了分析,进一步展望了其在农业中的开发动向及应用潜力。     

Herbicides and the Regulation of Pesticide Usage in Brazil

Abstract

Groundnut rust (Puccinia arachidis Speg.) is widely spread in Zambia and is a new threat to groundnut crops in Africa. Fungicides tested for Cercospora control were also effective when both rust and leafspot occurred and yield increases up to 102% were obtained. The most effective chemicals were chlorothalonil, mancozeb plus benomyl and a mixture of mancozeb, benomyl and fentin.     

The Design and Synthesis of Inhibitors of Imidazoleglycerol Phosphate Dehydratase as Potential Herbicides

The discovery and exploration of a new class of broad-spectrum post-emergent herbicides with a novel mode of action, namely the disruption of histidine biosynthesis via inhibition of imidazoleglycerol phosphate dehydratase (IGPD; E.C. 4.2.1.19), are described. Clear structural similarities between the first member, produced during an attempt to produce analogues of glyphosate, and intermediates in histidine biosynthesis were noted. Several series of targets were designed, to mimic both the enzyme substrate and a putative reaction intermediate, and synthesised. Some examples were found to be both extremely potent inhibitors of the enzyme, having K_i values as low as 0·3 nM , and phloem-mobile herbicides with levels of weed control similar to those shown by glyphosate. Further logical progress awaits a high-resolution X-ray structure determination of an enzyme-inhibitor complex. © 1997 SCI     

太行山山前平原作物系数与降水年型关系探讨

利用中国科学院栾城农业生态系统试验站1995~2001气象数据和同期大型称重式蒸渗仪监测的小麦、玉米蒸散量,采用参考作物法探讨分析了小麦、玉米生长期作物系数与降水年型的关系。结果表明,不同降水年型下小麦生长期作物系数差异不明显,统计时段内小麦生育期作物系数平均值为0.90,丰水年玉米生长期作物系数偏高,平均值为1.2,而平水年与枯水年玉米生长期作物系数差异不明显,平均值为0.94。为准确估算作物需水量,实现精确灌溉,建议尽量采用长系列观测数据确定的不同降水年型的作物系数,尤其是在玉米生长期。     

近45年气候变化对哲盟作物生产潜力的影响

分析哲盟近４５年气候变化对作物生产潜力的影响,结果表明：光合物产潜力有减少的趋势;温度升高使得光温生产潜力变幅减少;受降水变率大的影响,气候生产潜力变幅最大。并从生产潜力的角度,说明了解决农业灌溉问题和充分利用热量的增加是适应气候变化,提高作物现实生产力的关键。     

干旱半干旱地区灌溉农业中的遥感应用

灌溉农业是我国干旱半干旱地区农业发展的主要组成部分.目前,我国灌区的灌溉管理和信息化程度总体上处于较低水平,限制了灌区农业发展,遥感技术的应用将促进灌区灌溉管理水平的提高.以宁夏青铜峡灌区为例,对灌区耕地资源及其主要变化类型、灌区土地盐渍化现象及调整力度较大的作物种植结构进行遥感监测与分析,有效地补充了传统获取手段的不足,为灌区管理与合理规划提供了基础资料.     

The Potential Benefits of Weeds with Reference to Small Holder Agriculture in Africa

Weed control is one of the most important crop protection activities undertaken in both intensive and low-input farming systems. However, even under intensive systems, crop protection which is less dependent on pesticides may require that weeds be managed to obtain a balance between crop and non-crop vegetation to encourage an increase in natural enemies of crop pests. In the low-input farming systems which sustain much of the rural population of Africa, weed control is usually done by hand and clean weeding is often beyond the labour resources of the farming family. The vegetational diversity of peasant agriculture in Africa to which weeds make their contribution, helps to decrease the risk of disease and pest epidemics. In addition to the pest control benefits of a diverse agroecosystem, weeds contribute to the resource base of the rural community, providing a source of secondary foods, medicines and insecticides. Weed control within an integrated crop protection system appropriate to the needs of the resource-poor farmer, requires that weeds are managed in such a way that their biodiversity is maintained and the more useful species retained within the field or field margin. Those weeds with high food potential or which have pesticidal or medicinal properties might be deliberately encouraged within the crop or field margins. Certain weed species may harbour important pests or diseases of local crops and therefore should be selectively removed. The paper reviews and discusses the literature on the beneficial and deleterious effects of weeds and argues for a weed management strategy which balances the effects of weed competition on crop production with the ethnobotanical and pest control attributes of individual weed species and weed communities.     

河南省不同生态区CERES-Maize模型参数确定及精度验证

本研究将河南夏玉米主产区划分为4个生态区,利用全省18个站近十余年农气观测资料对CERESMaize模型进行参数调试和验证,其中2003—2005年为模型调参年份,2006—2010年为模型验证年份。根据各生态区的多站点调参验证的平均状态,获得4套模型区域品种参数。由各生态区夏玉米品种遗传参数可知,I区全生育期所需积温最多,其次是Ⅲ区和Ⅳ区;单穗潜在最大籽粒数Ⅰ区最高,Ⅲ区次之,Ⅳ区最低;灌浆速率参数Ⅲ区略小,其他地区较相近。各生态区生物量和产量的模拟和验证结果表明,归一化均方根误差NRMSE均小于20%,模型对各生态区生物量和产量模拟能力较强。但各生态区模拟效果有一定差异,其中生物量调试结果中观测值与模拟值均值较接近,验证结果中实测值较模拟值普遍偏大,尤其是Ⅰ区和Ⅱ区。在产量验证中,Ⅰ区和Ⅱ区模拟值略低于观测值,而Ⅲ区和Ⅳ区模拟值略高于观测值。Ⅰ-Ⅲ区生物量和产量的观测值和模拟值相关系数r均通过显著检验,模型对于这些地区生物量及产量增减的变化趋势模拟较好。对生物量和叶面积指数的动态模拟及验证结果表明,地上部总生物量动态增长的拟合效果较好。叶面积指数观测值略滞后于模拟值,但总体趋势吻合度较好。     

地膜覆盖和除草剂对夏玉米田杂草及玉米生长发育的影响

研究了地膜覆盖和除草剂对夏玉米田杂草和玉米生长发育的影响.结果表明,在玉米3～5叶期施药,药后33 d,杂草数量降至最低,56％2甲4氯钠可湿性粉剂处理的杂草减退率和相对株防效分别比40 g/L烟嘧磺隆油分散制剂提高了11.71百分点和12.65百分点.揭膜后,白色地膜覆盖下杂草的平均鲜重显著低于对照,比对照减少73.25％,相对鲜重防效分别是黑色地膜覆盖、56％2甲4氯钠可湿性粉剂、40 g/L烟嘧磺隆油分散制剂处理的1.12、1.15、1.73倍.地膜覆盖出苗率高且整齐一致,平均株高和叶数比对照高,对玉米的穗粒重、百粒重及其产量有明显的增效作用,以白色地膜覆盖下玉米产量最高,增产率比黑色地膜覆盖的高1.23百分点,比40g/L烟嘧磺隆油分散制剂处理高16.09百分点;而施用56％2甲4氯钠可湿性粉剂严重影响了玉米产量的形成,其产量比对照降低3.09％.     

Assessment of leaf cover and crop soil cover in weed harrowing research using digital images

Objective assessment of crop soil cover, defined as the percentage of leaf cover that has been buried in soil because of weed harrowing, is crucial to further progress in post‐emergence weed harrowing research. Up to now, crop soil cover has been assessed by visual scores, which are biased and context‐dependent. The aim of this study was to investigate whether digital image analysis is a feasible method to estimate crop soil cover in the early growth stages of cereals. Two main questions were examined: (i) how to capture suitable digital images under field conditions with a standard high‐resolution digital camera and (ii) how to analyse the images with an automated digital image analysis procedure. The importance of light conditions, camera angle, size of recorded area, growth stage and direction of harrowing were investigated, in order to establish a standard for image capture and an automated image analysis procedure based on the excess green colour index was developed. The study shows that the automated digital image analysis procedure provided reliable estimations of leaf cover, defined as the proportion of pixels in digital images determined to be green, which were used to estimate crop soil cover. A standard for image capture is suggested and it is recommended that digital image analysis be used to estimate crop soil cover in future research. The prospects of using digital image analysis in future weed harrowing research are discussed.     

Some Proposed Changes in the Legislation Governing the use of Toxic Chemicals in Agriculture in Britain

Abstract

The climate, soil types, vegetation, land use and crops of The Gambia are briefly introduced. The most important weeds are commented on and a checklist of 219 species is appended. Methods of weed control in current use and which are undergoing research and development are described. They include hand cultivations, animal-drawn equipment, herbicides and fallow management. Current training of farmers and agricultural staff is mentioned.     

2019年我国草地贪夜蛾扩散为害规律观测

草地贪夜蛾Spodoptera frugiperda(J.E.Smith)侵入我国后呈现快速蔓延为害态势,对我国玉米安全生产造成较大威胁。本文通过全国范围的系统监测,总结了2019年我国草地贪夜蛾侵入扩散区域、为害作物种类、发生面积、发生时间、虫口密度和为害情况。监测结果显示,玉米是我国草地贪夜蛾为害最重的作物。草地贪夜蛾在长江以南地区普遍发生,发生区域由南至北逐步扩散,虫口密度由南至北逐步递减,发生时间西部早于东部,虫口密度西部大于东部。缅甸是我国2019年重要的虫源地,未来应加强对缅甸、泰国和越南等东南亚国家虫源的监测;我国热带和南亚热带存在冬繁区,应尽快摸清其区域和面积;分析了草地贪夜蛾在我国可能发生的代次,提出南方春玉米的种植对草地贪夜蛾起到诱集作用,可延缓或减轻其北迁的时间和虫量,因此,应重视我国玉米品种和种植方式的合理布局,实现对草地贪夜蛾的长期有效治理。     

夏玉米茎流速率变化规律及其影响因子研究

采用FLOW32-1K包裹式茎流计测量茎流速率,分析2018年夏玉米(郑单958)蒸腾量(本研究采用茎流)与气象因子,包括净辐射、温度、饱和水汽压差(VPD)、风速的相关性,并以Pearson相关性系数进行评价。结果显示:试验期间土壤含水率保持在田间持水率的70%～80%,得出在玉米不受水分胁迫条件下,茎流速率与净辐射、温度、VPD、风速均呈线性相关,相关系数分别为0.754、0.622、0.674、0.443,表明太阳辐射与茎流速率关系最密切,与风速关系最小。在夏玉米生长吐丝期、灌浆期和成熟期,晴天时茎流速率日变化为单峰曲线,早上5∶00茎流开始启动,随后茎流速率逐渐上升,在11∶00茎流速率达到峰值74.5 g·h~(-1),随后又降低,一般在21∶00降低为0.0。雨天时由于大气辐射不稳定,表现为多峰曲线,且茎流速率波动较大(0～37.7 g·h~(-1))。经计算夏玉米在灌浆生长期叶面积指数稳定在4.4,这时基础作物系数K_(cb)为1.0,9月10日后显著下降,至收获时(10月1日)降低至0.55。     

Weed seedling emergence in contrasting fodder crop systems following 30 years of cultivation in the lowlands of Northern Italy

Five fodder crop systems of different intensity (ranging from a double annual crop of Italian ryegrass + silage maize to a permanent meadow) were adopted for 30 years in the lowlands of Northern Italy under two input levels, differing mainly in their provision of organic fertiliser (manure). Herbicides were used in the maize crops included in all systems, except the meadow. After 30 years, the weed seedbank of all systems and input levels were assessed by the seedling emergence technique on soil samples from each plot. The cropping systems determined the abundance and composition of the weed assembly. Relatively few, frequent species made up the majority of the emerged seedlings in all systems, and there was no relationship between the total number of emerged seedlings and the mean number of species recorded in the different systems. Arabidopsis thaliana and Oxalis corniculata were abundant in the annual double crop and in the 3- and 6-year rotations that also comprised the annual double crop. These weeds, however, were unlikely to represent a major threat to the crops, due to their vigour and growth period. The permanent meadow tended to greater weed biodiversity than the other systems. The application of manure favoured the seedbank of species such as Lolium multiflorum, Digitaria sanguinalis and A. thaliana. Weed communities in the different systems were mainly determined by herbicide application, (through the ability of weeds to avoid its effects, determined by the weed life history and emergence period) and manure application (with its possible dual effect of spreading weed seeds and favouring nitrogen-responsive weeds).     

2019年江苏省草地贪夜蛾发生及为害情况调查

为掌握草地贪夜蛾在江苏省的发生及为害情况,在开展系统监测和田间调查的基础上,对2019年草地贪夜蛾在江苏省的发生动态及玉米受害情况进行了总结.结果表明,2019年5月入侵江苏苏南地区后,逐步向北扩散,6-7月是其主要扩散期.2019年江苏省玉米受草地贪夜蛾为害面积约3 440.3 hm2.其中,夏玉米发生面积最大、占7...     

The importance of light quality in crop–weed competition

Plant competition is thought to be driven by limiting resources. We propose that plant competition is triggered initially by the red to far-red light ratio (R:FR) originating from neighbouring plants, followed by a series of complex physiological processes, which exclude direct resource competition. Field experiments were conducted in 2005 and 2006 in which maize ( Zea mays ) was grown hydroponically. The effect of R:FR signal being reflected from the leaf surface of Amaranthus retroflexus was isolated by avoiding direct competition for light, water and nutrients. Results showed that the low R:FR reflected from the leaf surface of A. retroflexus did alter the carbon allocation pattern of maize when compared with maize growing free of weeds. Prior to silking, maize grown under low R:FR experienced temporal changes in plant height, persistent changes throughout the sampling period in root and shoot dry weights and rate of leaf appearance, but no changes in leaf area. At silking, low R:FR reduced ear and total plant dry weight. These results support the hypothesis that changes in R:FR acts as an early signal of pending competition by initiating a shade avoidance response. Data from this experiment suggest that once a plant is physiologically triggered into a shade avoidance response, these plants do so at a physiological cost, which may constrain plant development and possibly reduce reproductive fitness.     

黄土区夏玉米叶面积指数变化规律的研究

通过对连续4a夏玉米叶面积指数的研究,建立了夏玉米叶面积指数与积温之间的归一化模型,提出了精确的且唯一确定的归一化方法。多年的叶面积动态变化用同一方程式表达,提高了方程的可信度,可用于作物生长模拟和作物生长监测和遥感估产。     

钙对低温胁迫下玉米幼苗氧化损伤的保护作用

采用室内盆栽试验,利用不同浓度的CaCl₂（0、5、10、15、20 mmol·L^-1）处理低温胁迫下的玉米幼苗,研究了钙对玉米幼苗抗冷性的作用。结果表明：与对照相比,低温处理明显抑制了玉米幼苗的生长,减缓了可溶性蛋白和可溶性糖含量的积累,抗氧化酶活性下降,脯氨酸含量减少,丙二醛（MDA）含量增加,质膜透性增大。适宜浓度的钙（5～10 mmol·L^-1）能减缓低温胁迫下玉米幼苗质膜相对透性和丙二醛（MDA）含量的增加,促进脯氨酸(Pro)、可溶性糖和可溶性蛋白的积累,提高超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）活性,其中10 mmol·L^-1 Ca²⁺处理的效果最为明显。