Resumo -O objetivo deste trabalho foi avaliar genótipos de milho quanto à resistência ao acamamento e ao quebramento do colmo e apresentar metodologia para avaliar essas características. Os ensaios foram realizados em blocos ao acaso, com 85 genótipos tropicais de milho e quatro repetições, em cinco locais. Foram avaliadas: as forças necessárias para o arranquio da planta e para o quebramento do colmo e o ângulo no momento do quebramento. As medições foram realizadas com equipamentos desenvolvidos para essas finalidades. Foram realizadas análises de variância e teste de Scott-Knott quanto às características. As forças de arranquio da planta, de quebramento do colmo e ângulo no momento do quebramento do colmo interagiram significativamente com a localidade. As médias variaram de 49,43 a 76,03 kgf para a força de arranquio da planta, de 1,07 kgf a 2,76 kgf para força de quebramento do colmo, e de 16,15 a 41,18º para o ângulo de quebramento do colmo. Existe variabilidade genética para seleção quanto à resistência ao acamamento e ao quebramento do colmo em genótipos tropicais de milho. A metodologia apresentada é eficiente para a avaliação e discriminação de genótipos.Termos para indexação: Zea mays, avaliação de genótipo, metodologia de avaliação. Resistance to lodging and culm breakage in tropical cornAbstract -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.Index terms: Zea mays, genotypic evaluation, evaluation methodology. IntroduçãoNa produção mundial de milho são estimadas perdas anuais de 5 a 20%, em consequência do acamamento e do quebramento do colmo (Instituto FNP, 2007). Os efeitos desses caracteres sobre o rendimento de grãos dependem principalmente do genótipo, da severidade e da fase de desenvolvimento da cultura em que eles se manifestam (Federizzi et al., 1994).O acamamento pode ser definido como um estado permanente de modificação da posição do colmo em relação à posição original, o que resulta em plantas recurvadas e até mesmo na quebra de colmos. O pr...

BackgroundAstrocaryum aculeatum is a palm tree species native to the tropical regions of South America, exploited commercially by local farmers for the pulp extracted from its fruits. The objective of this research was to compare the genetic diversity between adult plants and seedlings from open-pollinated seeds, quantify the pollen flow and dispersal, the spatial genetic structure, and the effective size of a population that has been continuously harvested for its fruits. The study was carried out in a natural population of A. aculeatum distributed over approximately 8 ha in the State of Amazonas (Brazil), separated by 400 m from the closest neighboring population. In total, 112 potential pollen donors, 12 mother plants and 120 offspring were mapped and genotyped.ResultsGenetic diversity was high for parents and the offspring. The fixation indexes for adults (F = -0.035) and offspring (F = -0.060) were negative and not significant. A significant spatial genetic structure was detected for the adult plants (up to the distance of 45 m) indicating short-distance seed dispersal. Paternity analysis detected 9.2 % of pollen immigration and the average distance of pollination within the population was 81 m. The average effective pollination neighborhood area between plants was 1.51 ha.ConclusionsOur results indicate that substantial introduction of new alleles has occurred in the population through pollen immigration, contributing to the maintenance of genetic diversity. Conservation efforts aimed at maintaining the gene pool of the current population or establishing new populations should utilize offspring from mother plants selected to be spaced by at least 50 m to prevent collecting seeds from relatives.

IIIQuantificação da área foliar e efeito da desfolha em componentes de produção de milho

-This study aimed to characterize the genetic diversity of buriti populations by AFLP (Amplified Fragment Length

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In Brazil, sacha inchi oil is produced by hand from plant materials with no breeding or detailed information about the chemical composition of seeds. In addition, most of the current information on the agronomic traits of this species originates from research carried out in the Peruvian Amazon. In order to promote the research and cultivation of sacha inchi in the Brazilian territory, this study aimed to analyze, in the central Amazon region, different accessions of this oilseed for characteristics of production and quality of fruits and seeds, as well as to estimate genetic parameters, through mixed models, with identification of superior accessions, for breeding purposes. A total of 37 non-domesticated accessions were evaluated in a randomized block design, with five replications and two plants per plot. The average oil content in seeds was 29.07 % and unsaturated fatty acids amounted to 91.5 % of the total fat content. For the yield traits, the estimates of individual broad-sense heritability were moderate (~0.33), while the heritability based on the average of progenies resulted in a selective accuracy of approximately 0.85. The use of the selection index provided simultaneous gains for yield traits (> 40 %) and oil yield. A high genetic variability was observed for the main traits of commercial interest for the species, as well as promising perspectives for the development of superior varieties for agro-industrial use.

Morphological characterization of Amazon pepper accessionsIn Brazil wide variability is found in peppers of Capsicum genus and the Amazon region is an important center of diversity. Information about the diversity in collection is useful, among other aspects, to increase the efficiency of breeding studies of cultivated species. The present study aimed to characterize the morphology and estimate the genetic diversity of 40 Capsicum accessions from Universidade Federal do Amazonas germplasm collection. Morphological descriptors recommended by IPGRI (International Plant Genetic Resources Institute), for the Capsicum and sensory analysis for pungency and flavor were used to characterize the accessions. Seventeen descriptors, identified as essentials, were used to calculate the genetic similarity among accessions, considering the general similarity coefficient of Gower. The hierarchical method of the average of the distances UPGMA (Unweighted Pair-Group Method using an Arithmetic Average) and PCO (Principal Coordinates Analysis) were used to cluster the accessions. Three species were found comprising 35 accessions of C. chinense, one of C. baccatum and four C. frutescens. Phenotypic variation among accessions was observed mainly on fruit characteristics that showed differences in size, shape, color and pungency. Several chilli peppers morphotypes were identified: two accessions of murupi; two lady's finger; four from "malagueta"; seven from fisheye; 13 from smell pepper, and 12 curabiá. Cluster and dispersion graph analysis were concordant in clustering accessions with small genetic distance. The collection presents a wide variation among accessions.

• 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.