Estimativa de parâmetros genéticos em caracteres de sementes e crescimento inicial de mudas de Ormosia excelsa Benth

Abstract

Omosia excelsa Benth is a native forest species, endemic to Brazil, popularly known as yellow tento, has pharmacological, ornamental and its wood potential is highly appreciated by the extractive community. It has rapid germination and emergence of seedlings. It is found in igapó environments, being a promising species for recovery of riparian forests. The present work had as objective to study the genetic variability in O. excelsa progenies and to estimate genetic parameters for seed germination traits and initial seedling growth. For the study of germination, we evaluated 26 progenies of a population of the municipality of Autazes, Amazonas. The germination of the seeds was carried out in two concomitant experiments, in the laboratory of the Native Seeds Center of Amazonas, in a germination chamber, where the progenies in experiment 1 were submitted to a constant temperature of 30 ºC and in experiment 2 at a constant temperature of 35 °C. The experimental design was the completely randomized, consisting of 26 progenies, 4 replicates and 25 seeds per plot. The evaluated characters were Percentage of germination (PG), Germination speed index (IVG), Mean germination time (TMG) and Germination synchronization index (ISG). Genetic and phenotypic variances and correlations, coefficient of genetic variation, heritability in the broad sense and gain by direct selection were estimated. Progenies submitted to a temperature of 35 ºC were taken to the Center for Environmental Studies and Research (CEPEAM) to monitor growth. In the area of seedling production, the height of the shoot (cm), collection diameter (mm) and number of leaves of the seedlings were measured. The experiment was carried out in a completely randomized design, with 22 progenies, in 5 replicates, 10 plants per plot, totaling 1,100 seedlings. Progenies of O. excelsa showed significant genetic variability for TG, IVG, ISG and TMG traits. In the direct selection considering the germination and the lower TMG, the progenies 9, 1, 7, 8, 18 and 22, 20, 10, 24, and 17 respectively presented higher in the environment at 30 ºC. Progenies 15, 10, 12, 7, 1 and 5, 12, 6, 13 and 9, respectively, were higher in the environment at 35ºC, for TG and TMG, and indicated For the production of seedlings. Fifteen seeds are sufficient to perform the biometric analyzes of O. excelsa seeds with a minimum accuracy of 85%, reducing the effort to analyze many seeds.