The prevalence of itchmite, Psorergates ovis, among sheep flocks with a history of fleece derangement     

PW JOHNSON  JW PLANT  JC BORAY  SC BLUNT  PJ NICHOLLS 《Australian veterinary journal》1990,67(4):117-120

An investigation of sheep flocks in the main sheep raising areas of New South Wales showed that the itchmite Psorergates ovis was frequently associated with fleece derangement. In 26 of the 41 flocks examined, P. ovis was the only ectoparasite detected. P. ovis and the sheep body louse Damalinia ovis, were found in 5 flocks. No external parasites were found on sheep examined from the 10 remaining flocks. The type of fleece derangement most frequently recorded was rubbing which in some cases was combined with areas of chewed fleece. Among flocks, there were positive relations between the prevalence of fleece derangement and prevalence of itchmite or scurf and between itchmite count and mean scurf score. Within flocks, itchmite infested sheep or sheep with scurf had higher prevalences of fleece derangement than sheep on which no mites or no scurf were found. Itchmite infested sheep had a higher prevalence of scurf than those with no detectable mite infestation. There were no significant differences in itchmite populations or fleece derangement between untreated flocks and flocks treated with synthetic pyrethroids, organophosphates or arsenic and rotenone.  相似文献   

Meiotic behavior of passion fruit somatic hybrids, Passiflora edulis f. flavicarpa Degener + P. amethystina Mikan   总被引：1，自引：0，他引：1  

L.V. Barbosa  M.L.C. Vieira 《Euphytica》1997,98(1-2):121-127

Somatic hybrids (SH) obtained by protoplast fusion were investigated for meiotic behavior in order to determine their possible use in breeding programs. Flower buds from four genotypes of SH between P. edulis f. flavicarpa (E) and the wild species P. amethystina (Am) denoted SH (E + Am) # 12, # 13, # 28 and # 35 were collected and the microsporocytes analysed. Meiotic phases showed the presence of abnormalities such as univalents, bivalents and quadrivalents, laggard chromosomes and anaphase bridges. At least 14 bivalents were observed in most of the cells of the hybrid plants. The percentage of cells with quadrivalents ranged from 73.3 in (E + Am) # 13 to 93.3 in (E + Am) # 28 and # 35. Analysis of pollen viability (V) indicated V = 88.23% for # 12, V = 83.86% for # 13, V = 84.20% for # 28, and V = 72.90% for # 35, and fruit development was observed. The high pollen viability, together with the multivalent pairing observed in the four somatic hybrids indicates that these materials can be used for the genetic improvement of yellow passion fruits aiming at introgressions of genes for resistance to diseases and pests. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Selection strategy in families of energy cane based on biomass production and quality traits     

Luís Cláudio Inácio da Silveira  Bruno Portela Brasileiro  Volmir Kist  Heroldo Weber  Edelclaiton Daros  Luiz Alexandre Peternelli  Márcio Henrique Pereira Barbosa 《Euphytica》2015,204(2):443-455

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Implications of early selection for grain colour on iron and zinc content and productivity of common bean          下载免费PDF全文

Rita de Kássia Siqueira Teixeira  Dayane Cristina Lima  Ângela de Fátima Barbosa Abreu  Magno Antonio Patto Ramalho 《Plant Breeding》2015,134(2):193-196

Brazilian consumers prefer beans of the beige grain colour. Common beans help supply dietary requirements for iron and zinc. The objectives of this study were (i) to determine whether early selection for grain colour affects the iron and zinc content and the grain yield in common beans and (ii) if an association between these characteristics was found, to obtain lines of carioca‐type grains with a high iron and zinc content and good grain yield. We evaluated 96 F_3:4, F_3:5 and F_3:6 progeny at two locations for iron and zinc content and grain yield. We selected 48 progeny for grain colour and chose 48 others at random. We found that early selection for grain colour does not affect the zinc content and grain yield. A positive and high association was found between iron and zinc content, and both iron and zinc content were slightly negatively correlated with grain yield. It is possible to obtain common bean lines combining a high iron and zinc content with good grain yield as long as a selection index is used.  相似文献   

Implications of the number of years assessment on recommendation of common bean cultivars          下载免费PDF全文

Ricardo Augusto Diniz Cabral Ferreira  Magno Antonio Patto Ramalho  Fernando Henrique Ribeiro Barrozo Toledo  Angela de Fátima Barbosa Abreu 《Plant Breeding》2015,134(5):599-604

In the common bean crop in Brazil, the requirement of the value for cultivation and use trials is that these experiments must be conducted over two years in three locations per region. Information in regard to the necessary number of years to ensure precision in cultivar recommendation and the influence of evaluated years in the estimation of the GE interaction are still scarce. Using grain yield of five check varieties assessed over 11 years in three sowing seasons per year, the aims of this study are as follows: to measure the relative contribution of the GE interaction, evaluating the implication of the number of years in the estimates of the GE interaction, and infer how many years are needed to ensure precision in cultivar recommendation. For instances, analysis of variance was carried out involving all environments and also combinations of years. The results showed that the GE interaction was greater than all other cross‐effects involving lines. The use of at least two years allows good coincidence in cultivar recommendation compared to the whole period. Increasing the evaluation time is a good strategy, especially when it is difficult to grow three different sowing seasons.  相似文献   

Herbage utilisation efficiency of continuously stocked pastures during periods of restricted pasture growth     

Tiago Miqueloto  Cauby de Medeiros Neto  Clovis David Medeiros Martins  Rodrigo Amorim Barbosa  Sila Carneiro Da Silva  André Fischer Sbrissia 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2020,70(3):208-214

ABSTRACT

The aim of this study was to evaluate the defoliation patterns of individual tillers, efficiency of herbage utilisation, and forage production in continuously stocked Brachiaria humidicola cv. Comum swards during periods of the year of restricted pasture growth. The experiment was conducted at the Embrapa, Campo Grande-MS, Brazil, from April to October 2012. Treatments consisted of two grazing management strategies, defined by two ranges of sward height (10–15 and 20–25 cm) managed under continuous and variable stocking rates. The experiment was conducted as a completely randomised block design with three replications. During periods of resource constraints, grazing management strategies based on ‘steady state’ sward heights did not alter defoliation patterns, herbage utilisation efficiency (HUE), and forage production in Brachiaria humidicola swards under a continuous stocking method. A direct implication of our results is that grazing management strategies during the driest and coldest periods of the year in the tropics should be developed based on the conditions most suitable for better promoting faster pasture recovery and a return to production in the following spring; it is unlikely that any grazing management strategy would be successful in increasing herbage production and/or HUE in periods of restricted pasture growth.  相似文献   

Endosperm protein synthesis in maize mutants with increased lysine content     

Misra PS  Jambunathan R  Mertz ET  Glover DV  Barbosa HM  McWhirter KS 《Science (New York, N.Y.)》1972,176(4042):1425-1427

The endosperm proteins of the maize mutants, opaque-2, opaque-7, floury-2, brittle-2, and the double mutant of opaque-2 and brittle-2, were separated into five soluble fractions by the Landry-Moureaux method. As compared to their isogenic normal counterparts, the mutant endosperms had higher concentrations of albumins, globulins, and glutelin-3, and lower concentrations of prolamines. The combination of the opaque-2 and brittle-2 genes enhanced this difference. Although the four mutant genes are located on three different chromosomes, they exert a similar effect on endosperm protein composition. Five other starchmodifying mutants with high lysine content resemble the brittle-2 mutant in endosperm protein composition, when the gene is present either singly or combined with opaque-2. Therefore, the pattern of protein synthesis in all maize mutants with high lysine concentrations may be either identical or very similar. Because no synergistic effect on lysine concentration is obtained when floury-2 is combined with opaque-2, different pathways leading to reduced zein synthesis may exist in the floury and starch-modifying mutants with high lysine concentrations.  相似文献   

Response: mediation of interactions among insect herbivores     

Raupp MJ  Barbosa P  Leonhardt BA 《Science (New York, N.Y.)》1986,234(4783):1588-1589

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Direct measurement of the current-phase relation of a superfluid 3He-B weak link     

S Backhaus  SV Pereverzev  A Loshak  JC Davis  RE Packard 《Science (New York, N.Y.)》1997,278(5342):1435-1438

Direct measurements of the current-phase relation, I versus Deltaphi, for a weak link coupling two reservoirs of B-phase superfluid helium-3 (3He-B) were made over a wide range of temperatures. The weak link consists of a square array of 100-nanometer-diameter apertures. For temperatures T such that T/Tc >/= 0.6 (where Tc is the superfluid transition temperature), I approximately sin(Deltaphi). At lower temperatures, I(Deltaphi) approaches a straight line. Several remarkable phenomena heretofore inaccessible to superconducting Josephson junctions, including direct observation of quantum oscillations and continuous knowledge of Deltaphi, were also observed.  相似文献   

Methylcyclopentanoid monoterpenes mediate interactions among insect herbivores     

Raupp MJ  Milan FR  Barbosa P  Leonhardt BA 《Science (New York, N.Y.)》1986,232(4756):1408-1410

Beetles secrete an array of chemicals generally believed to mitigate attack by predators. Methylcyclopentanoid monoterpenes secreted by larvae of the willow leaf beetle, Plagiodera versicolora, deter feeding by conspecific adults. Furthermore, the secretion elicits a strong repugnancy response in larvae of another willow herbivore, Nymphalis antiopa. Leaves bearing beetle larvae are less likely than leaves not bearing beetles to be frequented and consumed by Nymphalis larvae. Predator defense may not be the sole function of glandular secretions produced by herbivorous insects; secretions may also mediate interactions among herbivores that use a common resource.  相似文献