Effect of Nitrogen and Trinexapac-Ethyl Rates on the SPAD Index of Wheat Leaves     

Marcelo Curitiba Espindula  Valterley Soares Rocha  Paulo Cezar Rezende Fontes  Raul Carvalho Corrêa da Silva  Leandro Torres de Souza 《Journal of plant nutrition》2013,36(11):1956-1964

ABSTRACT

The objective of this study was to evaluate the effect of nitrogen (N) and trinexapac-ethyl (TE) rates on the SPAD index in wheat flag leaf. The treatments were five N rates (30, 60, 90, 120, 150 kg ha^?1) combined with four TE rates (0, 63, 125, 188 g ha^?1). The experiment was carried out in a randomized block design with four repetitions. SPAD index, leaf N content and grain yield showed quadratic response to the increase in N rates, whereas area, wet and dry weight of flag leaf presented linear increase. TE caused linear increase in SPAD index, linear decrease in leaf area, reduction in grain yield with smaller N rates and increase with larger N rates. The N content, and the wet and dry weight of flag leaf were not affected by TE. SPAD calibration to estimate N status in wheat should be specific for each TE rate.  相似文献   

Genetic diversity and path analysis for nitrogen use efficiency in popcorn inbred lines     

Gabriel Borges Mundim  José Marcelo Soriano Viana  Ciro Maia  Geísa Pinheiro Paes  Rodrigo Oliveira DeLima 《Euphytica》2013,191(2):291-299

Popcorn inbred lines with more efficient nitrogen use are better able to uptake nitrogen from the soil and convert it into higher grain yield, resulting in lower environmental and economic impacts caused by nitrogen fertilization. The objectives of this study were to (i) identify inbred lines superior in nitrogen use (ii) assess the genetic diversity between popcorn inbred lines under high and low N conditions and (iii) investigate the causal effects of several traits in nitrogen use efficiency (NUE). We evaluated 25 popcorn inbred lines under high and low N, and several traits related to NUE and its components were measured. Efficient and inefficient inbred lines under both N levels were identified and can be useful for generating a segregating population for quantitative trait loci mapping. The genetic diversity assessment based on phenotypic traits grouped the inbred lines into four clusters under both N levels, and the efficient inbred lines were grouped together, as were the inefficient lines. The most divergent inbred lines under high N were classified as efficient and intermediate and can be useful to generate a divergent breeding population with a high frequency of favorable genes for NUE. Nitrogen uptake efficiency (NUpE) was considered the most important trait for NUE. To improve the accuracy of selection for NUE, a selection index involving the total root length (TRL), daily growth and NUpE traits under both N levels is recommended, as these traits had high correlations with and direct effects on NUE.  相似文献   

Flaxseed (Linum usitatissimum L.) and Its Total Non-digestible Fraction Influence the Expression of Genes Involved in Azoxymethane-induced Colon Cancer in Rats     

Marcelo Hernández-Salazar  Ramón G. Guevara-González  Andrés Cruz-Hernández  Lorenzo Guevara-Olvera  Luis Arturo Bello-Pérez  Eduardo Castaño-Tostado  Guadalupe Loarca-Piña 《Plant foods for human nutrition (Dordrecht, Netherlands)》2013,68(3):259-267

The influence of flaxseed (Linum usitatissimum L.) and its total non-digestible fraction (TNDF) on the expression of genes involved in azoxymethane (AOM)-induced colon cancer in Sprague Dawley rats was analyzed. The dose used in the animal model was two tablespoons of flaxseed per day, which is the dose recommended for humans. Flaxseed significantly decreased the crypt multiplicity (10.50?±?3.5) compared with the AOM treatment (34.00?±?11.0), which suggests that flaxseed exhibits a preventive effect against colon cancer. Both treatments (flaxseed and TNDF) influence the overexpression of genes involved in cell cycle arrest and mitochondrial apoptosis: p53, p21, bcl-2, bax and caspase-3. Flaxseed induced the expression of p53 and p21, whereas TNDF triggered the p21-independent expression of p53. This finding suggests that both of these treatments induced cell cycle arrest. In addition, TNDF induced mitochondrial apoptosis because the TNDF + AOM group exhibited the expression of caspase-3, decreased bcl-2 expression and increased bax expression. These results suggest that the expression of the analyzed genes is associated with the presence of dietary antioxidants linked to the cell wall of flaxseed.  相似文献   

Relationship Between Height Growth and Foliar Nutrient N and P Concentration in a Eucalyptus grandis Plantation in Northeastern Argentina     

Sarah L. Burns  Carolina A. Pérez  Marcelo F. Arturi  Juan F. Goya  Corina Graciano 《Journal of Sustainable Forestry》2013,32(4):313-320

The relationship between the height growth, foliar concentrations of nitrogen (N) and phosphorus (P), and the N:P ratio was analyzed in a fourth rotation plantation that did not respond to fertilization with these nutrients. Spearman's nonparametric correlation analysis was used to evaluate the association between growth in height—calculated as the difference between heights measured at 1 yr and 2 yr after planting—and foliar N and P concentrations, as well as N:P ratio, determined in the 1-yr-old plantation. Only a weak positive correlation between height growth and foliar P concentration in planted seedlings was found. A significant negative relation was observed between the growth and N:P ratio in seedlings. Foliar concentrations suggest that there were neither P nor N limitations for growth in the analyzed period. This may be due to the management of harvest residues, which were abandoned on-site without burning.  相似文献   

Identification of origin and analysis of population structure of field-selected imidazolinone-herbicide resistant red rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>)     

Ives Clayton Gomes dos Reis Goulart  Marcelo Teixeira Pacheco  Anderson Luis Nunes  Aldo MerottoJr 《Euphytica》2012,187(3):437-447

Several red rice biotypes have evolved resistance to imidazolinone herbicides. The origin of resistance has been attributed to gene flow from the herbicide-resistant rice cultivars, but independent evolution of spontaneous mutation can also contribute to the herbicide resistance. The objective of this study was to quantify the occurrence of gene flow and independent selection as the mechanisms of origin of imidazolinone-resistance in red rice to correctly define the management practices for red rice control. Three single nucleotide polymorphism markers were used to identify acetolactate synthase (ALS) gene mutations, and four simple sequence repeat markers were used to identify hybrids of imidazolinone-resistant rice cultivars and red rice. In addition, genetic diversity and population structure analyses were performed. Artificial hybrids were used as controls. Gene flow was the main origin of imidazolinone herbicide resistance, but independent selection occurred in 1.1 % of the evaluated red rice plants. Two red rice plants that independently evolved herbicide resistance had the ALS gene mutation, Gly₆₅₄Glu. Population structure analysis also indicated intense gene flow from rice cultivars to red rice, but some populations maintained a high genetic identity based on a small amount of gene introgression from the rice cultivars. These results indicate the importance of adopting controls of red rice escapees to avoid gene flow from the imidazolinone-resistant rice, and the necessity of biotechnological approaches to mitigating gene flow in the development of new herbicide-resistant rice cultivars.  相似文献   

Using binary and probabilistic habitat availability indices derived from graph theory to model bird occurrence in fragmented forests     

Marcelo Awade  Danilo Boscolo  Jean Paul Metzger 《Landscape Ecology》2012,27(2):185-198

Loss of connectivity is one of the main causes of decreases in habitat availability and, thus, in species abundance and occurrence in fragmented landscapes. It is therefore important to measure habitat connectivity for conservation purposes, but there are several difficulties in quantifying connectivity, including the need for species movement behavioral data and the existence of few consistent indices to describe such data. In the present study, we used a graph theoretical framework to measure habitat availability, and we evaluate whether this variable is adequate to explain the occurrence pattern of an Atlantic rainforest bird (Pyriglena leucoptera, Thamnophilidae). The playback technique was used to parameterize the connectivity component of habitat availability indices and to determine the presence or absence of the study species in forest patches. Patch- and landscape-level habitat availability indices were considered as explanatory variables. Two of these were landscape-level indices, which varied in terms of how inter-patch connections are defined, using either a binary or probabilistic approach. This study produced four striking results. First, even short open gaps may disrupt habitat continuity for P. leucoptera. Second, the occurrence of P. leucoptera was positively affected by habitat availability. Third, proper measures of this explanatory variable should account for the landscape context around the focal patch, emphasizing the importance of habitat connectivity. Finally, habitat availability indices should consider probabilistic and not binary inter-patch connections when intending to explain the occurrence of bird species in fragmented landscapes. We discuss some conservation implications of our results, stressing the advantages of an ecologically scaled graph theoretical framework.  相似文献   

Optimized protocol for multiplex nested polymerase chain reaction to detect and differentiate Haemophilus parasuis,Streptococcus suis,and Mycoplasma hyorhinis in formalin-fixed,paraffin-embedded tissues from pigs with polyserositis     

Ikjae Kang  Duyeol Kim  Kiwon Han  Hwi Won Seo  Yeonsu Oh  Changhoon Park  Jeehoon Lee  Marcelo Gottschalk  Chanhee Chae 《Canadian journal of veterinary research》2012,76(3):195-200

An optimized protocol was developed for the simultaneous detection and differentiation of Haemophilus parasuis, Streptococcus suis, and Mycoplasma hyorhinis in formalin-fixed, paraffin-embedded (FFPE) tissues with multiplex nested polymerase chain reaction (PCR). This method also determines the prevalence of these bacteria in pigs with polyserositis. DNA extraction with a combination of a commercial reagent and proteinase K resulted in more frequent detection of the pathogens than DNA extraction with proteinase K alone. Among FFPE tissue samples from 312 cases of polyserositis in which at least 1 bacterial species was detected, multiplex nested PCR detected H. parasuis in 239 (77%), S. suis in 124 (40%), and M. hyorhinis in 40 (13%). The disease was caused by a single pathogen in 224 (72%) of the cases and multiple pathogens in 88 (28%). Among the pigs positive for H. parasuis, S. suis, and M. hyorhinis by multiplex nested PCR, the pathogen was isolated from only 11%, 35%, and 28%, respectively. Therefore, the PCR protocol developed in this study is a useful diagnostic method when samples are negative after isolation methods and even for samples in which only 1 pathogen was isolated.  相似文献   

Geostatistical analysis of fruit yield and detachment force in coffee     

Gabriel Araújo e Silva Ferraz  Fábio Moreira da Silva  Marcelo de Carvalho Alves  Rafael de Lima Bueno  Pedro Augusto Negrini da Costa 《Precision Agriculture》2012,13(1):76-89

The aim of this study was to use geostatistical analysis to evaluate the spatial variation in the detachment force of coffee fruit and coffee yield by variograms and kriging for precision agriculture. This study was conducted at Brej?o farm, Três Pontas, Minas Gerais, Brazil. The detachment force of green and mature coffee fruit was measured with a prototype dynamometer and georeferenced. The yield data were obtained from manual harvesting and were georeferenced. The data were evaluated by variograms estimated by residual maximum likelihood (REML), which provided a satisfactory approach for modeling all the variables with a small sample size. Spherical and exponential models were fitted, the first provided the better fit to mature fruit detachment force and the latter provided the better fit to coffee yield and green fruit detachment force. They were used to describe the structure and magnitude of spatial variation in the variables studied. Kriged estimates were obtained with the best fitting variogram models and mapped. The statistical and geostatistical analyses enabled us to characterize the spatial variation of the detachment force of green and mature coffee fruit and coffee yield and to visualize the spatial relations among these variables. The precision agriculture techniques used in this paper to collect, map and analyze the variables studied will help coffee farmers to manage their fields. Maps of coffee yield will enable farmers to apply nutrients site-specifically and manage harvesting either manually or mechanically. In addition, maps of detachment force of coffee fruit can enable farmers to harvest coffee selectively by choosing the appropriate places and the right time to start. This will improve the quality of the final product and also increase profits.  相似文献   

Axial forces and bending moments in the loaded rabbit tibia in vivo     

Janin Reifenrath  Daniel Gottschalk  Nina Angrisani  Silke Besdo  Andrea Meyer-Lindenberg 《Acta veterinaria Scandinavica》2012,54(1):21

Background

Different animal models are used as fracture models in orthopaedic research prior to implant use in humans, although biomechanical forces can differ to a great extend between species due to variable anatomic conditions, particularly with regard to the gait. The rabbit is an often used fracture model, but biomechanical data are very rare. The objective of the present study was to measure axial forces, bending moments, and bending axis directly in the rabbit tibia in vivo. The following hypothesis was tested: Axial forces and bending moments in the mid-diaphysis of rabbit tibia differ from other experimental animals or indirectly calculated data.

Methods

A minifixateur system with 4 force sensors was developed and attached to rabbit tibia (n = 4), which were subsequently ostectomised. Axial forces, bending moments and bending angles were calculated telemetrically during weight bearing in motion between 6 and 42 days post operation.

Results

Highest single values were 201% body weight [% bw] for axial forces and 409% bw cm for bending moments. Whereas there was a continous decrease in axial forces over time after day 10 (P = 0.03 on day 15), a decrease in bending moments was inconsistent (P = 0.03 on day 27). High values for bending moments were frequently, but not consistently, associated with high values for axial forces.

Conclusion

Axial forces in rabbit tibia exceeded axial forces in sheep, and differed from indirectly calculated data. The rabbit is an appropriate fracture model because axial loads and bending moments in rabbit tibia were more closely to human conditions than in sheep tibia as an animal model.  相似文献   

Analysis of longitudinal data of beef cattle raised on pasture from northern Brazil using nonlinear models     

Fernando B. Lopes  Marcelo C. da Silva  Ednira G. Marques  Concepta M. McManus 《Tropical animal health and production》2012,44(8):1945-1951

This study was undertaken to aim of estimating the genetic parameters and trends for asymptotic weight (A) and maturity rate (k) of Nellore cattle from northern Brazil. The data set was made available by the Brazilian Association of Zebu Breeders and collected between the years of 1997 and 2007. The Von Bertalanffy, Brody, Gompertz, and logistic nonlinear models were fitted by the Gauss?CNewton method to weight?Cage data of 45,895 animals collected quarterly of the birth to 750?days old. The curve parameters were analyzed using the procedures GLM and CORR. The estimation of (co)variance components and genetic parameters was obtained using the MTDFREML software. The estimated heritability coefficients were 0.21?±?0.013 and 0.25?±?0.014 for asymptotic weight and maturity rate, respectively. This indicates that selection for any trait shall results in genetic progress in the herd. The genetic correlation between A and k was negative (?0.57?±?0.03) and indicated that animals selected for high maturity rate shall result in low asymptotic weight. The Von Bertalanffy function is adequate to establish the mean growth patterns and to predict the adult weight of Nellore cattle. This model is more accurate in predicting the birth weight of these animals and has better overall fit. The prediction of adult weight using nonlinear functions can be accurate when growth curve parameters and their (co)variance components are estimated jointly. The model used in this study can be applied to the prediction of mature weight in herds where a portion of the animals are culled before they reach the adult age.  相似文献