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531.
Identification of citrus hybrids through the combination of leaf apex morphology and SSR markers 总被引:5,自引:0,他引:5
Antonio Carlos de Oliveira Aristides Novac Garcia Mariângela Cristofani Marcos Antônio Machado 《Euphytica》2002,128(3):397-403
Citrus breeding programs normally face several biological obstacles such as apomixis and polyembryony that result in a cumbersome
identification of hybrid seedlings. The main purpose of this work is to describe the combined use of visual selection based
on the leaf apex morphology and SSR analysis to differentiate hybrid from nucellar seedlings derived from the cross between
the ‘Murcott’ tangor [Citrus reticulata Blanco × Citrus sinensis (L.) Osb.] and ‘Pêra’ sweet orange [Citrus sinensis(L.) Osb.]. A new morphological variable named leaf apex morphometric index is also described as the quantitative basis of
the visual selection. The efficiency of visual selection of hybrids was tested under two growth conditions, seedlings germinated
in seedbeds and in plastic tubes. Putative hybrid seedlings were also confirmed through the analysis of simple sequence repeats
(SSR). The visual selection of hybrid seedlings resulted in an increase of 87.2% (p < 0.01) and 202.2% (p <0.001) in the number of correctly identified hybrids when compared to the method of random picking of seedlings in seedbeds
and plastic tubes,respectively. The results indicate that the combination of visual selection and SSR analysis for the identification
of hybrids derived from the cross of polyembryonic citrus cultivars will improve the accuracy of the selection,save time,
and reduce the costs involved in the use of molecular markers alone in citrus breeding programs.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
532.
Maria Regina Gmach Klaus Kaiser Maurício Roberto Cherubin Carlos Eduardo Pellegrino Cerri Izaias Pinheiro Lisboa Ana Luisa Soares Vasconcelos Marcos Siqueira‐Neto 《Soil Use and Management》2021,37(1):126-137
Global demand for bioenergy increases interest in biomass‐derived fuels, as ethanol from sugarcane straw. However, straw is the main carbon source to soil and its removal reduces C input, affecting active fractions (dissolved organic carbon, DOC) and C storage. To quantify the effects of straw removal on DOC and C stocks, we built lysimeter system using soil (Rhodic Kandiudox) from sugarcane field. We evaluated four soil depths (1, 20, 50 and 100 cm) and four straw removal rates: no removal NR, medium MR, high HR and total TR, leaving 12, 6, 3 and 0 Mg/ha on the soil surface, respectively. After rainfall, drainage water was collected and analysed for DOC content. Soil C stocks were determined after the 17‐month. Total DOC released at 1‐cm depth amounted to 606, 500, 441 and 157 kg/ha in NR, MR, HR and TR, respectively. Net‐DOC suggests straw as the main source of DOC. Most of DOC in NR (50%) was retained within the 1–20 cm layer, resulting in higher C stock (10 Mg/ha) in the topsoil. In HR and MR, DOC retention was higher within 20–50 cm, suggesting differences in DOC composition. DOC in TR was 40% higher at 20 cm than at 1 cm, indicating C losses from topsoil. Low concentrations of DOC were found at 100‐cm depth, but representing 30% in TR. Straw removal for bioenergy production is sustainable, but we should leave at least 3 Mg/ha of straw to ensure DOC production and soil C storage, taking account the DOC contribution to key soil functions. 相似文献
533.
Ricardo Henrique Ribeiro Marcos Renan Besen Priscila Luzia Simon Cimelio Bayer Jonatas Thiago Piva 《Soil Use and Management》2020,36(3):420-428
Nitrogen (N) gas losses can be reduced by using enhanced-efficiency N (EEN) fertilizers such as urease inhibitors and coating technologies. In this work, we assessed the potential of EEN fertilizers to reduce winter losses of nitrous oxide (N2O-N) and ammonia (NH3-N) from a subtropical field experiment on a clayey Inceptisol under no-till in Southern Brazil. The EEN sources used included urea containing N-(n-butyl) thiophosphoric triamide (UR+NBPT), polymer-coated urea (P-CU) and copper-and-boron-coated urea (CuB-CU) in addition to common urea (UR) and a control treatment without N fertilizer application. N2O-N and NH3-N losses were assessed by using the static chamber method and semi-open static collectors, respectively. Both N2O-N and NH3-N exhibited two large peaks with an intervening period of low soil moisture and air temperature. Although the short-term effect was limited to the first few days after application, UR + NBPT urea decreased soil N2O-N emissions by 38% relative to UR. In contrast, urease inhibitor technology had no effect on NH3-N volatilization. Both coating technologies (CuB-CU and P-CU) were ineffective in reducing N losses via N2O production or NH3 volatilization. The N2O emission factor (% N applied released as N2O) was unaffected by all N sources and amounted to only 0.48% of N applied—roughly one-half the default factor of IPCC Tier 1 (1%). Based on our findings, using NBPT-treated urea in the cold winter season in subtropical agroecosystems provides environmental benefits in the form of reduced soil N2O emissions; however, fertilizer coating technologies provide no agronomic (NH3) or environmental (N2O) advantages. 相似文献
534.
535.
Investigation of co‐infections with pathogens associated with gill disease in Atlantic salmon during an amoebic gill disease outbreak 下载免费PDF全文
J K Downes T Yatabe M Marcos‐Lopez H D Rodger E MacCarthy I O'Connor E Collins N M Ruane 《Journal of fish diseases》2018,41(8):1217-1227
Gill diseases are a complex and multifactorial challenge for marine farmed Atlantic salmon. Co‐infections with putative pathogens are common on farms; however, there is a lack of knowledge in relation to the potential effect co‐infections may have on pathology. The objective of this study was to determine the prevalence and potential effects of Neoparamoeba perurans, Desmozoon lepeophtherii, Candidatus Branchiomonas cysticola, Tenacibaculum maritimum and salmon gill poxvirus (SGPV) during a longitudinal study on a marine Atlantic salmon farm. Real‐time PCR was used to determine the presence and sequential infection patterns of these pathogens on gill samples collected from stocking until harvest. A number of multilevel models were used to determine the effect of these putative pathogens on gill health (measured as gill histopathology score), while adjusting for the effect of water temperature and time since the last freshwater treatment. Results indicate that between 12 and 16 weeks post‐seawater transfer (wpst), colonization of the gills by all pathogens had commenced and by week 16 of marine production each of the pathogens had been detected. D. lepeophtherii and Candidatus B. cysticola were by far the most prevalent of the potential pathogens detected during this study. Detections of T. maritimum were found to be significantly correlated with temperature showing distinct seasonality. Salmon gill poxvirus was found to be highly sporadic and detected in the first sampling point, suggesting a carryover from the freshwater stage of production. Finally, the model results indicated no clear effect between any of the pathogens. Additionally, the models showed that the only variable which had a consistent effect on the histology score was N. perurans. 相似文献
536.
Segura D Monreal L Pérez-Pujol S Pino M Ordinas A Brugués R White JG Escolar G 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(3):581-588
We studied equine platelet function and activation using ultrastructural examination, flow cytometry, and perfusion. The main aim of the study was to evaluate hemostatic mechanisms in horses using these techniques. Ultrastructural observations were done on resting and activated platelets. Flow cytometry was used to evaluate binding of antibodies to major platelet glycoproteins (GPIIb-IIIa, GPIV, and GPIb) and activation-dependent antigens (P-selectin and lysosomal integral membrane protein [LIMP]). Perfusion techniques were used to evaluate the interaction between platelets and damaged subendothelium. Aggregation experiments were done to identify the best agonists for flow cytometry. Ultrastructural observations confirmed that equine platelets lack a developed open canalicular system and that release of granule contents occurs by fusion of adjacent granule membranes that ultimately connect with external membranes. Flow cytometry identified a 2-fold increase in binding of antibodies against GPIIb-IIIa and GPIV after activation. Binding of antibodies against P-selectin and LIMP increased from 2.12 and 1.74% to 15.5 and 11.6%, respectively, in response to thrombin and to 21.86 and 10.50%, respectively, in response to collagen. Annexin V binding increased moderately after activation. Perfusion experiments with citrated blood indicated that equine platelets react more strongly to subendothelium than do human platelets. When blood was anticoagulated with low molecular weight heparin, a marked impairment of platelet interactions was observed. In conclusion, although some differences were observed between human and equine platelet function, some techniques currently used to assess human platelet function may be useful to assess equine platelets. 相似文献
537.
Field‐evolved resistance to Bt maize in sugarcane borer (Diatraea saccharalis) in Argentina 下载免费PDF全文
Damián A Grimi Betiana Parody María Laura Ramos Marcos Machado Federico Ocampo Alan Willse Samuel Martinelli Graham Head 《Pest management science》2018,74(4):905-913