Maria Teresa Gomes Lopes

Repetibilidade de características do fruto de aceroleira

The objective of this paper was to estimate the repeatability coefficient (RC) of the fruit traits such as height (FH), diameter (FD), weight (FW), C vitamin (VitC), total soluble solids (TSS), pulp weight/fruit weight relation (PFR) and the titrable acidity (TA), while the number of measures that should be performed for an efficient selection of the genotypes under evaluation were determined. Analysis were made using the ANOVA, principal components and structural analysis methodology. The estimates of the RC for FH, FD, FW, VitC and TA demonstrated high regularity at the superiority of the individuals from one cycle to another, so the evaluation of two cycles was enough to predict the individuals real value with R2 above 90%. To TSS, in average, eight evaluation cycles were necessary to reach a R2 above 90%. PFR showed to be highly irregular, so the evaluation of at least 26 cycles turned to be necessary in order to reach a R2 above 90%. Such an irregularity was attributed to the method used in analyzing the characteristic, then the search for a more accurate and stable method was necessary.

Repetibilidade da produção de cachos de híbridos interespecíficos entre o caiaué e o dendezeiro

RESUMO A hibridacao interespecifica entre o caiaue ( Elaeis oleifera (Kunth) Cortes) e o dendezeiro (E. guineensis Jacq.) tem sido explorada com o objetivo de desenvolver cultivares tao produtivas quanto as de dendezeiro, aliada a resistencia a pragas e doencas, principalmente o amarelecimento fatal, elevada taxa de acidos graxos insaturados e reducao de porte caracteristicas do caiaue. Por ser uma cultura perene com longo ciclo de producao, alem dos altos custos para manutencao e avaliacao dos experimentos de melhoramento genetico, e necessario definir o periodo minimo de avaliacao para que a selecao dos hibridos seja realizada com eficiencia e minimo dispendio de tempo e recursos. Este estudo teve como objetivo estimar os coeficientes de repetibilidade dos caracteres numero de cachos, peso total de cachos e peso medio de cachos de hibridos interespecificos e definir o numero de anos consecutivos de avaliacao necessario para selecao eficiente dos melhores cruzamentos e individuos. Os coeficientes de repetibilidade foram estimados pelos metodos da analise de variância, componentes principais com base na matriz de covariância (CPCV) e de correlacoes, e analise estrutural com base na matriz de correlacoes. O metodo dos CPCV demonstrou ser o mais adequado para o estudo da repetibilidade da producao de cachos, indicando quatro anos consecutivos de avaliacao para selecionar progenies, representadas por dez plantas, com coeficientes de determinacao (R 2 ) superiores a 85%, e que para selecao individual de plantas sao necessarios pelo menos seis anos consecutivos de avaliacao para atingir R 2 superior a 80%. PalavRaS-chavE: Elaeis guineensis, Elaeis oleifera, hibridacao, melhoramento genetico.

Resistência ao acamamento de plantas e ao quebramento do colmo em milho tropical

The objective of this work was to evaluate corn genotypes for resistance to lodging and to culm breakage and to describe a new method for evaluating these traits. Assays were carried out in randomized blocks, with 85 tropical genotypes of corn and four replicates in five localities. The force required to pull out the plant and to break the culm and the breaking angle of momentum were evaluated. The measurements were made with equipment developed specifically for this purpose. Variance analyses and the Scott‑Knott test were carried out for the traits. The forces required to pull out the plant and break the culm, and the breaking angle for the culms were significantly interactive with the locality. The means varied from 49.43 to 76.03 kgf for the force required to pull out the plants, from 1.07 to 2.76 kgf for the force required to break the culm, and from 16.15 to 41.18o for the angle at the breakage of the culm. There is genetic variability for selection for resistance to lodging and culm breakage in tropical corn. The method described is efficient for evaluating and differentiating the genotypes.

Controle genético da resistência à mancha-de-Phaeosphaeria em milho

The Phaeosphaeria leaf spot, of ample occurrence in Brazil, has been causing an expressive reduction in the corn yield in the country. Thus, the development of resistant hybrids to this disease is one of the main objectives of corn breeding programs. Information about the genetic control of resistance to the disease is necessary so that the programs can be efficient. The main goal of this study was to determine the genetic control of resistance to the Phaeosphaeria leaf spot in maize through the assessment of the generation means from two crossing between a resistant inbred line (DAS95 or DAS72) with a susceptible line (DAS21) under natural infection conditions of the disease. The experiment was carried out in Indianopolis (MG) in two sowen dates, October and November, 2000. The randomized blocks design with three repetitions was utilized. The evaluation to resistance was performed thirty days after the flowering using a diagrammatic scale of percentage of the total foliar tissue of the plant affected by the disease. Disease severity means of parental lines and generations F1, F2, RCP1 and RCP2 were analysed according to the model by MATHER & JINKS (1971). Genetic variation due to additive effects varied from 73% to 84% whilst dominant effects ranged from 13% to 23%. In both studied population, the predominance of gene additive over dominant effects was evidented. The inheritance values were high, varying from 61% to 88%. These results indicate favourable conditions to develop new resistance lines to Phaeosphaeria leaf spot with the studied populations.

Microsatellite loci for tucumã of Amazonas (Astrocaryum aculeatum) and amplification in other Arecaceae

UNLABELLED PREMISE OF THE STUDY Microsatellite loci were developed for tucumã of Amazonas (Astrocaryum aculeatum), and cross-species amplification was performed in six other Arecaceae, to investigate genetic diversity and population structure and to provide support for natural populations management. • METHODS AND RESULTS Fourteen microsatellite loci were isolated from a microsatellite-enriched genomic library and used to characterize two wild populations of tucumã of Amazonas (Manaus and Manicoré cities). The investigated loci displayed high polymorphism for both A. aculeatum populations, with a mean observed heterozygosity of 0.498. Amplification rates ranging from 50% to 93% were found for four Astrocaryum species and two additional species of Arecaceae. • CONCLUSIONS The information derived from the microsatellite markers developed here provides significant gains in conserved allelic richness and supports the implementation of several molecular breeding strategies for the Amazonian tucumã.

Genetic diversity in natural populations of Buriti (Mauritia flexuosa L. f.)

This study aimed to characterize the genetic diversity of buriti populations by AFLP (Amplified Fragment Length Polymorphism) markers. The analysis was performed in four populations used by traditional communities in the state of Amazonia (Bom Jesus do Anama, Lauro Sodre, Santa Luzia do Buicuzinho, and Esperanca II). From each population 30 plants were randomly selected. To obtain the markers four primer combinations were used. The percentage of polymorphic loci was estimated, the molecular variance among and within populations analyzed and a dendrogram constructed. The primers detected 339 polymorphic loci ranging from 81.1 % to 91.1 % among populations. Analysis of molecular variance attributed 77.18 % to variation within and 22.8 % to variation between populations. The dendrogram indicated the formation of two groups, showing that the populations of Bom Jesus do Anama and Lauro Sodre are genetically most similar and thet the genetic and geographical distances are not correlated.

Desempenho de cultivares de alface na região de Manaus

In the evaluation of vegetable cultivars, the high average yield in the competition assays associated to quality factors are utilized as criteria to recommend cultivars. In the present work we evaluated the lettuce cultivars Frisella, Deisy, Tender Green, Lollo Bionda, Itapua 401, Marisa, Veronica, Banchu New Red Fire and Hortencia under the climatic conditions of the region of Manaus, under protected and conventional cultivation. The evaluated characteristics were: total and commercial weight, plant diameter and height. The lettuce cultivars Marisa, Itapua 401 and Hortencia presented higher production in both environments adding Veronica with best production under conventional cultivation.

Inheritance of resistance to anthracnose stalk rot (Colletotrichum graminicola) in tropical maize inbred lines

applied into the stalk. Internal lesion length was directly measured by opening the stalk thirty days after inoculation. Results indicated contrasting modes of inheritance. In one population, dominant gene effects predominated. Besides, additive x dominant and additive x additive interactions were also found. Intermediate values of heritability indicated a complex resistance inheritance probably conditioned by several genes of small effects. An additive-dominant genetic model sufficed to explain the varia tion in the second population, where additive gene effects predominated. Few genes of major effects control disease resistance in this cross. Heterosis widely differed between populations, which can be attributed to the genetic background of the parental resistant lines.

Contribution of the institutions in the Northern region of Brazil to the development of plant cultivars and their impact on agriculture

This paper describes the development of breeding programs in northern Brazil and their main impacts on agriculture. Their contribution to the breeding of the species palm oil, acai fruit, cacao, cupuacu, guarana, tomato, camu-camu, cocona, peach palm, and rubber was laid out in detail. Advances in breeding programs of institutions such as Embrapa, Ceplac, Inpa, and Universities require investments in infrastructure and in human and financial resources to ensure continuity and efficiency in economic, social and environmental gains. The improvement of native species, the main focus of the breeding programs of the institutions in the Northern region of Brazil, is a form of exploiting the Amazonian biodiversity for the benefit of society. Therefore, policies to foster research institutions should be a subject of deliberation and action of the scientific and technological community in Brazil.

Produção e qualidade de frutos de híbridos de pimentão (Capsicum annuum) em ambiente protegido em Manaus-AM

In the evaluation of vegetable varieties, the highest average yield in the competition assays combined with quality factors are used as criteria recommended for planting. The object of the present work was to evaluate five commercial sweet pepper hybrids protectively cultivated in climatic conditions of Manaus. The experiment was carried out in an arc type vegetation house, measuring 50.4m in length and 7m in width and covered with 100 microns of plastic. The experimental design consisted of randomized blocks with four replications and plots of 20 plants. The following characteristics were evaluated: weight (FW) and number (FN) of fruits produced by each plant, average weight (FAW), length (FL), diameter (FD) of fruits, and FL/ FD (RLD) relation. The data were submitted to analysis of variance and average comparison (Tukey). Although a significant effect of the total fruit weight was not verified, statistically significant differences occurred in the fruit traits. The Magali R and Nathalie hybrids, traditionally cultivated in protected environments in the Amazon, presented more elongated shaped fruits, which are preferred by consumers. The fruits of Safari R hybrids, though less elongated than the Magali R and Nathalie, presented a major weight average that satisfies the local market exigency, making it a good alternative to the diversification of cultivated hybrids.