ABSTRACT
Este trabalho tem por objetivo avaliar a precipitação pluvial e as temperaturas máximas e mínimas previstas pelo Modelo Eta para até 120 dias de previsão em 24 localidades distribuídas na região Centro-Sul do Brasil. A avaliação se baseia na comparação de séries históricas de chuva e temperaturas de 1997 a 2002, com as previsões de 30, 60 e 120 dias de antecedência do Modelo Eta para as 24 localidades. Foram utilizados valores de média, mediana e desvio padrão nesta avaliação. Os resultados indicam que estas previsões geralmente subestimam as chuvas e a amplitude térmica nestas localidades. Os menores erros de precipitação pluvial se localizam mais destacadamente em Itumbiara e Rio Verde, enquanto que os maiores, em Porangatu e Manduri. Por outro lado, os menores erros de temperatura máxima se localizam destacadamente em Brasília, Manduri e Piracicaba, enquanto que os maiores ocorrem em Barreiras e Porangatu. Apesar de o modelo apresentar erros sistemáticos nas previsões de temperaturas, estes erros podem ser removidos para que os valores corrigidos possam ser introduzidos nos modelos de culturas.
The objective of this study was to evaluate the 120-day precipitation and maximum and minimum temperature forecasts by Eta Model over 24 locations around the Mid-Southern of Brazil. The evaluation was based on comparing observed time series of precipitation and temperatures from 1997 to 2002 to 30, 60 and 120-day forecasts of Eta Model over these 24 locations. Mean, median and standard deviation were used in the evaluation. The results show that these forecasts generally underestimate rain and temperature range. The smallest precipitation errors occurred in Itumbiara and Rio Verde, whereas the largest errors occurred in Porangatu and Manduri. The smallest maximum temperature errors occurred in Brasília, Manduri and Piracicaba whereas the largest errors in Barreiras and Porangatu. Despite the systematic errors exhibited by the precipitation and temperature forecasts, these errors can be removed and the corrected values input into the crop models.
ABSTRACT
The study of inbreeding depression is important for breeding strategies such as use of inbred progenies or extraction of inbreed lines. A diallel of 28 maize open-pollinated varieties was evaluated in 10 environments in the early 1990s. At the same time, S1 populations for each of the 28 varieties were evaluated in the same 10 experiments (environments). Yield reductions of the populations from S0 to S1 (mean of the 10 environments), varied from 34.6 percent (CMS-01) to 59.2 percent (CMS-30), with an average of 49.1 percent. Inbreeding depression was greater in populations with a wider genetic base, which had never been exposed to inbreeding (CMS-30, BR-107, PH4, Cunha, Saracura, Nitrodent, and Nitroflint). Inbred lines with greater yield means should be obtained from the BR-105, BR-111, CMS-01, CMS-03, BR-106, CMS-14c, and CMS-28 populations. The use of parameter estimates generated by analysis of inbreeding depression, allow to make inferences about frequencies of deleterious alleles in the population. The frequencies of favorable alleles in the parents can be obtained by diallel analysis. The association of these two types of information, can provide a better interpretation of the genetic parameters and also can improve the process of selection of parents for either an intra- or an inter-populational breeding program