Effects of hematite and ferrihydrite nanoparticles on germination and growth of maize seedlings

Engineered iron oxide nanoparticles (IO-NPs) have been used extensively for environmental remediation. It may cause the release IO-NPs to the environment affecting the functions of ecosystems. Plants are an important component of ecosystems and can be used for the evaluation of overall fate, transport and exposure pathways of IO-NPs in the environment. In this work, the effects of engineered ferrihydrite and hematite NPs on the germination and growth of maize are studied. The germination and growth of maize were done with treatments at different concentrations of hematite and ferrihydrite NPs, namely 1, 2, 4, and 6 g/L. Biological indicators of toxicity or stress in maize seedlings were not observed in treatments with engineered hematite and ferrihydrite NPs. In contrast, the NPs treatments increased the growth of maize and the chlorophyll content, except for hematite NPs at 6 g/L, where non-significant effects were found. The translocation of engineered ferrihydrite and hematite NPs in maize stems was demonstrated using confocal laser scanning microscopy.     

The impact of hybrids between genetically modified crop plants and their related species: introgression and weediness

Assessing the impact of hybrids between transgenic plants and nontarget wild species involves answering several questions such as: (i) what are the hybridization and introgression rates; (ii) what is the behaviour of a transgene in a wild population; and (iii) what will be the consequences of the expression of a transgene in a wild population? These issues are discussed using results from experiments on oilseed rape and wild related Brassiceae. Evidence is given of large variations in the estimates of cross-fertilization probabilities. The first stage of introgression into wild populations is demonstrated to occur spontaneously through back-crossing. Population analysis may also be valuable to detect traces of past introgression. Data from the literature on weed biology, and especially herbicide resistance, are used to illustrate the behaviour of a new gene in weed populations. The need for computer models simulating the introgression process is stressed.     

Sugar meal sources for the phlebotomine sandfly Lutzomyia longipalpis in Ceará State, Brazil

Abstract. In the Brazilian village of BoqueiraTo do Renato Parente, Ceará State, where visceral leishmaniasis is endemic, significant variation in the abundance of phlebotomine sandflies between different types of vegetation was demonstrated by castor oil sticky trap collections. Population densities of Lutzomyia longipalpis (Lutz & Neiva) sandflies were higher in beans and maize crops than in the surrounding open and tree scrub. Significant relationships were detected between the abundances of sandflies and aphids, suggesting aphid honey dew as a potential food source. Sugar meal analysis, using high-performance anion exchange (HPAE) chromatography with pulsed amperometric detection (PAD) and the cold anthrone test, was used to demonstrate that significantly more sandflies fed on bean plants contaminated with aphids and honeydew than on uncontaminated beans. Furthermore, higher concentrations of sugars were detected in flies which fed on aphid/honeydew-contaminated beans, suggesting that sugar was more easily available and/or that honeydew/aphids act as phagostimulants for sandflies. Amongst wild sandflies collected from a bean field, significantly more female sandflies were 'sugar-positive' than males, though the sugar concentrations in positive sandflies were similar for both sexes. The concentrations of di- and trisaccharides in sandfly homogenates, honeydew extracts and phloem exudates were very low.     

Light interception by grain legume row crops

Abstract. Four contrasting grain legume species ( Glycine max, Vigna radiata. Vigna mungo and Vigna angularis ) were grown as row crops with both 0.5 m and 1.0 m spacings between row centres. Light transmission profiles, at ground level, across rows of plants, were obtained for each crop on a number of occasions during growth. The proportion of the incident downward light flux density intercepted by each crop at solar noon was found to be simply and directly related to the product of the proportion of the ground area covered by the crop's leaf canopy and the proportion of the downward light flux density incident at the row centre that was intercepted by the crop. The average proportion of the incident light energy intercepted over the whole day could be related to the proportion intercepted at solar noon.     

国内外转基因作物产业化的比较

当前，全球转基因作物研发和产业化迅猛发展, 创造了巨大的经济、社会和生态效益。转基因作物产业化发展的快慢, 是关系到我国农业可持续发展和提高农产品国际竞争力的重大问题。就国内外转基因作物的产业化进行了优劣势比较, 并从影响转基因作物产业化的技术瓶颈和安全性监管两方面进行了探讨。     

Biology of the stem sawflies Trachelus tabidus and Cephus pygmaeus in the Negev of southern Israel

Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) stems in the Negev Desert of southern Israel are subject to mass infestations by stem sawflies larvae, primarily Trachelus tabidus F. (Cephidae, Hymenoptera). Infestations up to 55% and 50% in wheat and barley, respectively, were found in 1982/83. In addition, up to 8.6% of wild oat (Avena sp.) stems were cut by sawfly larvae in June 1983.The phenology of the insects was studied in 1981 to 1983 using yellow watertraps to catch adults and by dissecting infested stems to establish the pre-imaginal stages. Adults emerged at the end of February at magen and at the beginning of March at Gilat. Eggs and newly emerged larvae appeared in April. Larvae in diapause were found in cut stubs at the end of April and beginning of May. Pupae were found at the end of January and February.Of the sawfly specimens trapped in 1982 and 1983, the great majority was identified as T. tabidus and less than 5% as Cephus pygmaeus (Cephidae, Hymenoptera). The males of the sawflies appeared 4–6 days before the females, and were less numerous than them.About 12% of the larvae were parasitised by Tetrastichus sp. (Chalcidoidea, Eulophidae) in wheat, barley and wild oat, and about 4% by Collyria sp. (Ichneumoidea, Ichneumonidae) in wheat and barley stubs.

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Résumé Les tiges de blé et d'orge subissent des attaques massives de tenthrèdes dans le désert du Négev au Sud d'Israël. Des attaques atteignant 55 et 50,4% ont été observée respectivement sur blé et orge en 1982/83.De plus, jusqu'à 8,6% de tiges d'avoine sauvage ont été coupées par les larves de tenthrèdes en juin 1983.La phénologie des insectes a été étudiée de 1981 à 83 en utilisant des pièges jaunes pleins d'eau pour capturer les adultes et en disséquant les tiges attaquées pour déterminer les stades préimaginaux.Les adultes ont émergé à fin de février et au début mars. Les oeufs et les larves sont apparus en avril. Les larves en diapause ont été trouvées dans les souches coupées à la fin de janvier et en février.La grande majorité de Cephidae adultes piégés en 1982 et 1983 a été identifiée Trachelus tabidus F., Cephus pygmaeus L. correspondait à moins de 5%. Les mâles de tenthrèdes sont apparus 4 à 6 jours avant les femelles qui étaient plus nombreuses.Environ 12% des larves étaient parasitées par un eulophide (Tetrastichus sp.) sur blé, orge et avoine sauvage, tandis que 3,6% l'étainent par un ichneumonide (Collyria sp.) dans les souches de blé et d'orge.

     

Modeling spatial dependence and economic hotspots in landowners’ willingness to supply bioenergy crops in the northeastern United States

This paper investigates the spatial heterogeneity of landowners’ willingness to supply three bioenergy crops: switchgrass, Miscanthus, and willow, in the northeastern United States. Spatial heterogeneity might arise for several reasons. For example, landowners closer to bioenergy processing plants might be more likely to be willing to supply bioenergy crops, and landowners who are more willing to supply bioenergy crops may be spatially clustered because they share similar land attributes, demographics, experiences, and/or values. Using high‐resolution GIS data related to the location of pellet plants utilizing bioenergy crops and survey data related to landowners’ characteristics including spatial location, we estimate a spatial probit model to explain the variation in individual‐specific reservation prices (RPs)—the feedstock price at which landowners become willing to supply a bioenergy crop. We find that respondents’ RP is lower the closer they live to their nearest pellet plant and spatial dependency is only present for switchgrass supply. We also identify three economic hotspots (areas with high potential supply and low RPs) for each bioenergy crop. We believe that bioenergy supply chains could be developed around these hotspots.     

Assessing lignocellulosic biomass production from crop residues in the European Union: Modelling,analysis of the current scenario and drivers of interannual variability

This study assesses crop residues in the EU from major crops using empirical models to predict crop residues from yield statistics; furthermore it analyses the inter‐annual variability of those estimates over the period 1998‐2015, identifying its main drivers across Europe. The models were constructed based on an exhaustive collection of experimental data from scientific papers for the crops: wheat, barley, rye, oats, triticale, rice, maize, sorghum, rapeseed, sunflower, soybean, potato and sugarbeet. We discuss the assumptions on the relationship between yield and the harvest index, adopted by previous studies, to interpret the experimental data, quantify the uncertainties of these models, and establish the premises to implement them at regional scale –i.e., NUTS level 3– within the EU. To cope this, we created a consolidated sub‐national statistical data along with an algorithm able to aggregate (figures are provided at country level) and disaggregate (production at 25 km grid is provided assupplementary material) estimates. The total lignocellulosic biomass production in the EU28 over the review period, according to our models, is 419 Mt, from which wheat is the major contributor (155 Mt). Our results show that maize and rapeseed are the two crops with the highest residue yield, respectively 8.9 and 8.6 t ha‐1. The spatial analysis revealed that these three crops, which, according to our results, are feedstocks highly suitable a priori for second generation biofuels in the EU and are unevenly distributed across Europe. Weather fluctuation was identified as the major driver in residue production from cereals, while, in the case of starch crops and oilseeds – which are predominant in northern Europe – corresponded to the marked production trend likely influenced by the agricultural policies and agro‐management over the review period. Our results, among others, could help to understand and quantify the ecological boundaries of the bioeconomy from agriculture.     

转mCry1Ac基因玉米BT799对斑马鱼的生态毒理学效应

转基因作物的饲用安全性问题一直是人们关注的焦点之一.为评估转mCry1Ac基因玉米BT799对鱼类的生态毒理效应,本研究以斑马鱼为受试动物,设置5个处理:含20%转基因玉米膨化饲料组(GMF)、含20%亲本玉米膨化饲料组(PF)、转基因玉米粉(GMM)、亲本玉米粉(PMM)以及商业饲料对照组(CF),通过98 d的喂养试验,调查斑马鱼的生长表现、组织病理、繁殖、肝脏中抗氧化酶活性及敏感蛋白mRNA的表达水平.结果表明:转mCry1Ac基因玉米对斑马鱼的各项生长指标、肝脏、脑和肠道的组织病理、产卵量、受精卵孵化率、肝脏中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,以及SOD、CAT、热激蛋白70(HSP70)和卵黄蛋白原(VTG)mRNA表达量均无显著影响.但在试验后期,饲料组(GMF和PF)和玉米粉组(GMM和PMM)斑马鱼的体重、体长和特定生长率显著低于商业饲料组;饲料组斑马鱼的孵化率显著低于玉米粉组和商业饲料组;饲料组(3.85±0.76)雄鱼肝脏中的VTG mRNA表达量显著高于玉米粉组(1.60±0.56).研究表明,转mCry1Ac基因玉米对斑马鱼没有明显生态毒理效应,但由于配制的膨化饲料与商业饲料在营养成分和适口性上的差异,可能导致个别指标与商业饲料组相比有显著差异.