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991.
通过一个为期138d的饲养试验来测定日粮中粗甘油对生长猪的生长性能,胴体性状,肉质指标和组织结构的影响。本试验使用的粗甘油包含84.51%甘油、11.95%水、2.91%氯化钠和0.32%甲醇。试验选用断奶8天后的仔猪共96头(48头公猪和48头母猪,平均体重为7.9±0.4kg),按试验开始时的性别和体重分配到24个栏中(4头/栏)。日粮处理为玉米-豆粕型, 相似文献
992.
Mitchell D Stamm Tiffany M Heng‐Moss Frederick P Baxendale Blair D Siegfried Roch E Gaussoin Daniel D Snow David A Cassada 《Pest management science》2013,69(2):285-291
BACKGROUND: Neonicotinoid insecticides are generally efficacious against many turfgrass pests, including several important phloem‐feeding insects. However, inconsistencies in control of western chinch bugs, Blissus occiduus, have been documented in field efficacy studies. This research investigated the efficacy of three neonicotinoid insecticides (clothianidin, imidacloprid and thiamethoxam) against B. occiduus in buffalograss under field conditions and detected statistically significant differences in B. occiduus numbers among treatments. A subsequent study documented the relative quantity and degradation rate of these insecticides in buffalograss systemic leaf tissues, using HPLC. RESULTS: Neonicotinoid insecticides initially provided significant reductions in B. occiduus numbers, but mortality diminished over the course of the field studies. Furthermore, while all three neonicotinoids were present in the assayed buffalograss leaf tissues, imidacloprid concentrations were significantly higher than those of clothianidin and thiamethoxam. Over the course of the 28 day study, thiamethoxam concentrations declined 700‐fold, whereas imidacloprid and clothianidin declined only 70‐fold and 60‐fold respectively. CONCLUSIONS: Field studies continued to verify inconsistencies in B. occiduus control with neonicotinoid insecticides. This is the first study to document the relative concentrations of topically applied neonicotinoid insecticides in buffalograss systemic leaf tissues. Copyright © 2012 Society of Chemical Industry 相似文献
993.
Oded Cohen Ozgur Batuman Yoni Moskowits Alexander Rozov Elisha Gootwine Munir Mawassi Moshe Bar-Joseph 《Phytoparasitica》2005,33(2):141-148
Mechanical inoculations with contaminating tools and propagation of infected budwood were considered the main causes for the
omnipresence of multiple viroid species among citrus and other Middle Eastern and Mediterranean fruit trees and grapevines.
However, neither means could explain viroid infections of wild trees — scattered on terrains inaccessible to humans — nor
the finding of similar viroids among graft-incompatible plants. Northern hybridization of RNA extracts made of scrapings from
the surfaces of goat (Capra hircus) horns that were rubbed against etrog (Citrus medica) stems infected with a citrus viroids complex, revealed accumulation of considerable amounts ofCitrus exocortis viroids (CEVd) andHop stunt viroids (HSVd). Experimental transmission of both CEVd and HSVd was obtained by rubbing healthy citrus plants with goat horns that
had been rubbed 24 h earlier on infected etrog stems. These results implicate goats as possible vectors of viroids. Transmissionvia goats could have facilitated the long-range spread of viroids among cultivated and wild plants andvice versa and also among graft-incompatible plants. 相似文献
994.
C. P. Musoli F. Pinard A. Charrier A. Kangire G. M. ten Hoopen C. Kabole J. Ogwang D. Bieysse C. Cilas 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):451-460
Coffee wilt disease (CWD) caused by Fusarium xylarioides, considered to be a soil-inhabiting fungus, is endemic in several African countries, affecting commercially important coffee
species and causing serious economic losses. Coffee wilt disease development in naturally infected Coffea canephora fields at the Coffee Research Institute in Uganda was assessed from April 2001 to March 2006 to generate information about
temporal and spatial spread of the disease. Maps of diseased trees were also generated from the data. Semi-variance analysis
was performed on the data to show the spatio-temporal structure of disease. Host influence on the spatio-temporal structure
was deduced from the distribution pattern of diseased and healthy trees and analysis of variance. Results show that the temporal
disease epidemic progress was slow. The disease was found to spread from initial infections to healthy neighbouring trees,
resulting in an aggregated pattern. An infected tree could infect up to three healthy trees away, in any direction. Disease
foci formed and expanded with time, coalescing but punctuated in spots planted with resistant hosts. There were varying levels
of susceptibility among host genotypes, affecting the rates and levels of epidemic development. The implications of the findings
to the control of CWD are discussed. 相似文献
995.
996.
The rates at which (E)- and (Z)-mevinphos are hydrolysed in aqueous solutions in the pH range 8.7–11.5, and in the temperature range 30–50°C, have been measured. The overall activation parameters have been calculated, and equations to allow calculation of the rates in any basic conditions are given. The complicated routes by which (E)- and (Z)-mevinphos are hydrolysed to simple molecules have been deduced. The rates for the individual steps in each route have been either measured experimentally, or have been calculated through analogue simulation of all the reactions, by matching the calculated to the observed ultraviolet spectral changes during hydrolysis. It is proposed that (Z)-2-carboxyl-1-methylvinyl dimethyl phosphate is not observed as a hydrolysis product of (Z)-mevinphos because it decomposes by an extremely fast intramolecular reaction. The reasons for the greater lability of (E)-mevinphos are also discussed. 相似文献
997.
Susan L Steinberg Gerard J Kluitenberg Scott B Jones Nihad E Daidzic Lakshmi N Reddi Ming Xiao Markus Tuller Rebecca M Newman Dani Or J Iwan D Alexander 《Journal of the American Society for Horticultural Science》2005,130(5):767-774
Baked ceramic aggregates (fritted clay, arcillite) have been used for plant research both on the ground and in microgravity. Optimal control of water and air within the root zone in any gravity environment depends on physical and hydraulic properties of the aggregate, which were evaluated for 0.25-1-mm and 1-2-mm particle size distributions. The maximum bulk densities obtained by any packing technique were 0.68 and 0.64 g cm-3 for 0.25-1-mm and 1-2-mm particles, respectively. Wettable porosity obtained by infiltration with water was approximately 65%, substantially lower than total porosity of approximately 74%. Aggregate of both particle sizes exhibited a bimodal pore size distribution consisting of inter-aggregate macropores and intra-aggregate micropores, with the transition from macro- to microporosity beginning at volumetric water content of approximately 36% to 39%. For inter-aggregate water contents that support optimal plant growth there is 45% change in water content that occurs over a relatively small matric suction range of 0-20 cm H2O for 0.25-1-mm and 0 to -10 cm H2O for 1-2-mm aggregate. Hysteresis is substantial between draining and wetting aggregate, which results in as much as a approximately 10% to 20% difference in volumetric water content for a given matric potential. Hydraulic conductivity was approximately an order of magnitude higher for 1-2-mm than for 0.25-1-mm aggregate until significant drainage of the inter-aggregate pore space occurred. The large change in water content for a relatively small change in matric potential suggests that significant differences in water retention may be observed in microgravity as compared to earth. 相似文献
998.
Presettlement land survey records (PLSRs) are a valuable and unique source of information for the reconstruction of presettlement
forest patterns. The purpose of this study was to determine whether coarsely resolved PLSRs are adequate to characterize the
spatial patterns of individual tree species over large areas. The General Land Office Survey records of the PLSRs of Minnesota
were used and species selected in the analysis were based on their abundances and degrees of clustering. A geostatistical
procedure was developed to analyze observations of bearing-tree point-locations, at progressively coarser resolutions from
1×1 mile to 24×24 miles, to create spatially continuous probability surfaces of species occurrences across the landscape.
Statistical and visual analyses of the geostatistical predictions indicated that coarsely resolved PLSRs, as coarse as 24×24 miles,
can adequately represent the spatial pattern of individual species over large areas. Mean errors in predictions increased
as more coarsely resolved data were used, primarily in response to the decreased abundance of a species and minorly in response
to the degree of spatial clustering of a species. The results indicate that coarsely resolved township-level data of 6×6 miles
can be used for presettlement vegetation reconstruction of large areas of several counties. 相似文献
999.
S. Mancuso F. Ferrini F. P. Nicese 《The Journal of Horticultural Science and Biotechnology》2013,88(6):777-784
SummaryThe potential use of the artificial neural networks (ANNs) for characterization and identification of seventeen chestnut (Castanea sativa Mill.) accessions, belonging to the ``marrone''-type and ``chestnut''-type, was investigated in genotypes originating from regions of Italy. Different back-propagation neural networks (BPNN) were built on the basis of image analysis parameters of the leaves, for two tasks of chestnut classification. In the first case a BPNN was built and trained to differentiate the 17 accessions of chestnut. In the second case a BPNN was conceived to distinguish between the ``marrone'' and ``chestnut'' types. BPNN produced a clear identification of all the accessions except in the case of `Garrone nero', `Garrone rosso' and `Tempuriva', which showed almost the same output diagram. Cluster analysis separated the 17 chestnut genotypes into four main groups whose differences were related to the original sources of the genotypes and to the type of affiliation (``marrone''-type or ``chestnut''-type). Artificial neural network technique was also able to discriminate between ``marrone''-type and ``chestnut''-type accessions. Qualitative and quantitative rules for the image analysis parameters, useful for classifying chestnut accessions into these two types, were obtained. On the whole the relative importance of the leaf parameters reveals that ``typical'' leaves for ``marrone''-type are more elongated, of a darker colour and with a higher perimeter/area ratio than the leaves of the ``chestnut''-type. 相似文献
1000.
呼和浩特市生态环境脆弱性评价 总被引:1,自引:0,他引:1
生态环境脆弱性评价对认识、保护和改造生态环境,促进人与自然的和谐发展具有重要意义.应用AHP法、"敏感-弹性-压力"模型法,对呼和浩特市五个旗具进行生态脆弱件评价,探讨了呼和浩特市的生态环境脆弱性的主要特征,以及生态环境脆弱度的空间差异和不同区域生态环境脆弱性的主导成因.研究结果表明:各旗县区的生态环境脆弱性排序为武川... 相似文献