Melhoramento genético em abelhas. II. Teoria e avaliação de alguns métodos de seleção.

Apresentaram-se quatro metodos para se proceder a selecao, visando mais alta producao de mel em abelhas (tanto Apis mellifera como meliponideos, calcula-se o progresso esperado em cada um, analisam-se os componentes de variancia e definem-se os coeficientes de herdabilidade. Os metodos propostos sao os seguintes, exemplificandos supondo-se coeficientes de herdabilidade. h 2/1 = 0,40 e h 2/2 = 0,60: 1). Em populacoes de meliponideos - substituir as rainhas das piores colonias pelas melhores rainhas; as rainhas virgens das melhores colmeias voarao, se acasalarao e iniciarao postura. Supondo-se substituicao das 25% piores pelas 25% melhores, obtem-se um aumento de 15% por geracao; 2) Em populacao de Apis - substituir 25% das rainhas das piores colmeias por rainhas virgens provenientes das 25% melhores. O aumento esperado, nas condicoes expostas, e de 20% por geracao; 3) E igual ao numero 2, porem colocando-se quadro de zangoes em 25% das melhores colmeias. Se a substituicao, por esses machos selecionados, na nuvem de machos que fecundam as rainhas do apiario for 50%, entao o progresso esperado sera de 30%; 4) Quando 25% das melhores colonias recebem quadros de zangoes, e se estes alcancaram 50% da populacao de zangoes o progresso sera de 10% por geracao

Seleção de descritores na caracterização de germoplasma de Paspalum sp. por meio de componentes principais.

Foram avaliados 15 descritores reprodutivos, 22 vegetativos e 21 agronômicos, em que os agronômicos compreenderam sete descritores para a avaliação de inverno e sete descritores para a avaliação de verão, com o objetivo de selecionar os melhores descritores botânicos-agronômicos para caracterizar acessos das espécies Paspalum guenoarum e Paspalum plicatulum. Utilizou-se a análise de componentes principais para descartar os descritores reprodutivos, vegetativos e agronômicos, respectivamente, do conjunto inicialmente considerado. Foi possível selecionar, por intermédio desta técnica, oito descritores, considerados mais importantes na descrição da variabilidade presente na coleção de acesso do germoplasma estudado

Depressão endogâmica em uma população de melancia.

Este trabalho teve como objetivo estimar a depressão endogâmica em uma população segregante de melancia

Progresso genético em melancia.

Edição dos resumos expandidos do 45. Congresso Brasileiro de Olericultura; 15. Congresso Brasileiro de Floricultura e Plantas Ornamentais; 2. Congresso Brasileiro de Cultura de Tecidos de Plantas, Fortaleza, ago. 2005. 1 CD-ROM

The relation of the concentration of macronutrients in the substrate and in the foliage to cell wall thickness and cellulose concentration in the xylem of slash pine (Pinus elliotti)

Sand culture experiments, using a sub-irrigation technique, were installed in order to find out the effects of the macronutrients N, P, K, Ca, Mg and S on growth, aspect, mineral composition, length of fibers, thickness of cell wall and cellulose concentration in slash pine. The aim was to obtain, under controlled conditions, basic information which could eventually lead to practical means designed to increase the rate of growth and to make of slash pine a richer source of cellulose. Nitrogen, Phosphorus, Potassium Experiment A 3 x 3 x 3 factorial design with two replicates was used. Nitrogen was supplied initially at the levels of 25, 50 and 100 ppm; phosphorus was given at the rates of 5, 10 and 20 ppm; potassium was supplied at the rates of 25, 50 and 100 ppm; six months after the experiment was started the first level for each element was dropped to zero. Others macro and all micronutrients were supplied at uniform rates. Fifteen hours of illumination per day were provided. The experimental technique for growing the slash pine seedlings proved quite satisfactory. Symptoms of deficiency of nitrogen, phosphorus and potassium were observed, described and recorded in photographs and water colors. These informations will help to identify abnormalities which may appear under field conditions. Chemical analysis of the several plant parts, on the other hand, give a valuable means to assess the nutritional status of slash pine, thus confirming when needed, the visual diagnosis. The correctness of manurial pratices, on the other hand, can be judged with the help of the analytical data tabulated. Under the experimental conditions nitrogen caused the highest increases on growth, as measured by increments in height and dry weights, whereas the effects of phosphorus and potassium were less marked. Cellulose concentration was not significantly affected by the treatments used. Higher levels of N seemed to decrease both length of fiber elements and the thickness of cell wall. The effects of P and K were not well defined. Calcium, Magnesium, Sulfur Experiment A 3 x 3 x 3 factorial design with two replicates was used. Calcium was supplied initially at the levels of 12.5, 25 and 50 ppm; magnesium and sulfur were given at the rates of 6, 12.5 and 25 ppm. Other macro and micronutrients were supplied at uniform rates, common to all treatments. Three months after starting the experiment the first level for each element was dropped to zero. Symptoms of deficiency of calcium, magnesium and sulfur were observed, described and recorded as in the case of the previous experiment. Chemical analysis were made, both for mineral content and cellulose concentration. Length of fibers and thickness of cell wall were measured. Both calcium and magnesium increase height, sulfur failing to give significant response. Dry weight was beneficially affected by calcium and sulfur. The levels of calcium, magnesium and sulfur in the needles associated with deficiency and maximum growth are comparable with those found in the literature. Cellulose concentration increased when the level of sulfur in the substrate was raised. The thickness of cell wall was negatively affected by the treatments; no effect was observed with regards to length of fibers.Foram conduzidos experimentos fatoriais cultivando P. elliottii em solução nutritiva destinados a estudar o efeito de macronutrientes na composição mineral, grossura da parede celular e concentração da celulose no xilema. Os sintomas de deficiencia dos elementos foram descri tos e registrados. O crescimento foi estimulado por N, P, K, Ca e Mg, sendo a maior resposta devida ao N. Somente o enxofre aumentou significativamente o teor de celulose. A grossura da parede celular diminuiu com altos níveis de N, Ca, Mg e S; os primeiros diminuiram o comprimento das fibras

Population structures of Brazilian tall coconut ( Cocos nuciferaL.) by microsatellite markers.

In this study we investigated the genetic diversity of 10 populations of Brazilian Tall coconut trees, employing 13 SSR loci to characterize their genetic variability, population structure, and reproductive system

Sistema reprodutivo e suas implicações no melhoramento genético de uma população de melancia.

Este trabalho objetivou estimar a taxa de fecundação cruzada natural em uma população segregante para expressão sexual e discutir as implicações do sistema reprodutivo sobre o melhoramento genético e a estimação de parâmetros quantitativos em melancia

Genetic variability of garlic accessions as revealed by agro-morphological traits evaluated under different environments.

The cultivated garlic (Allium sativum L.) displays a wide phenotypic diversity, which is derived from natural mutations and phenotypic plasticity, due to dependence on soil type, moisture, latitude, altitude and cultural practices, leading to a large number of cultivars. This study aimed to evaluate the genetic variability shown by 63 garlic accessions belonging to Instituto Agronômico de Campinas and the Escola Superior de Agricultura ?Luiz de Queiroz? germplasm collections. We evaluated ten quantitative characters in experimental trials conducted under two localities of the State of São Paulo: Monte Alegre do Sul and Piracicaba, during the agricultural year of 2007, in a randomized blocks design with five replications. The Mahalanobis distance was used to measure genetic dissimilarities. The UPGMA method and Tocher?s method were used as clustering procedures. Results indicated significant variation among accessions (P < 0.01) for all evaluated characters, except for the percentage of secondary bulb growth in MAS, indicating the existence of genetic variation for bulb production, and germplasm evaluation considering different environments is more reliable for the characterization of the genotypic variability among garlic accessions, since it diminishes the environmental effects in the clustering of genotypes