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Vol. I : Grandes cultures. - 3e ed. revue et corrigée. - ISBN : 2-85794-177-3
Bibliografia : p. 315
Bibliografia : p. 395
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Vol. I : Grandes cultures. - 3e ed. revue et corrigée. - ISBN : 2-85794-177-3
Recursos e gestão da água
Produção de aquicultura
• Introduction
Tree genetic improvement programs usually lack, in general, pedigree information. Since molecular markers can be used to estimate the level of genetic similarity between individuals, we genotyped a sample of a Portuguese Eucalyptus globulus breeding population—a reference population of 125 individuals—with 16 microsatellites (SSR).
• Materials and methods
Using genotypes from the reference population, we developed a simulation approach to recurrently generate (105 replicates) virtual offspring with different relatedness: selfed, half-sib, full-sib and unrelated individuals. Four commonly used pairwise similarity coefficients were tested on these groups of simulated offspring. Significant deficits in heterozygosity were found for some markers in the reference population, likely due to the presence of null alleles. Therefore, the impact of null alleles in the relatedness estimates was also studied. We conservatively assumed that all homozygotes in the reference population were carriers of null alleles.
• Results
All estimators were unbiased, but one of them was better adjusted to our data set, even when null alleles were considered. The estimator’s accuracy and precision were validated with individuals of known pedigree obtained from controlled crosses made with the same reference population’s parents. Additionally, a clustering algorithm based on the estimator of choice was constructed, in order to infer the relatedness among 24 E. globulus elite individuals. We detected four putatively related elite individuals’ pairs (six pairs considering the presence of null alleles).
• Conclusions
This work demonstrates that in the absence of pedigree information, our approach could be useful to identify relatives and minimize consanguinity in breeding populations.
N2O emissions are affected by several factors, including type of fertilizer,
edafo-climatic conditions and mitigation measures applied. A field experiment was
carried out in central Portugal for two consecutive years, to evaluate the effect over soil
N2O emissions originated from the application of cattle slurry (CS) to a double-cropping
system producing maize and oats. The use of a nitrification inhibitor (DCD) was
evaluated as emission mitigation measure. A mineral fertilizer treatment (MIN) and a
Control were included and the DCD effects were tested together with MIN (MIN+DCD)
and CS (CS+DCD). Total N input was equal for all fertilizing treatments (oat 80 kg N ha-
1; maize 170 kg N ha-1). N2O fluxes were measure on 165 sampling dates, using a photoacoustic
spectroscopic infrared gas analyzer. The most important fluxes were observed 8-
10 days after fertilizer incorporation and during the following 20-40 days. Annual N2O-N
losses were higher in the first year, with a wettest autumn and a warmer summer than
usual. The highest values were measured with the use of mineral fertilizers (4.65 and 4.21
kg N ha-1 in MIN+DCD and MIN, respectively), which were 60-70% higher than those
measured with slurry application or without fertilization (1.85, 1.55 and 1.33 kg N ha-1 in
CS+DCD, CS and Control, respectively). Mean annual values of emission factor based
on N application (EF) were 0.76, 0.63, 0.12 and 0.07%, in MIN+DCD, MIN, CS and
CS+DCD, respectively. The DCD use, namely with mineral fertilizer, didn’t produce an
evident effect on total N2O losses.
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Composição dos alimentos
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Documentaçäo e informaçäo
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Documentaçäo e informaçäo
Genética e melhoramento vegetal
Bibliografia : f. 69
