Estimativa de parâmetros tecnológicos e genéticos de sementes de Ormosia discolor Spruce ex Benth.

Abstract

Ormosia discolor Spruce ex Benth. it is a native tree that occurs in the north of the state of Amazonas, known as "Tento Flamenguista", presents rapid growth and nodulation capacity, ideal for reforestation plantations. The objective of this work was to estimate technological and genetic parameters in a native O. discolor population. Twenty progenies were inventoried in the municipality of Autazes, AM, and height, DBH and crown diameter data were estimated. The technological parameters evaluated were determination of water content, biometrics and weight of one thousand seeds. For the estimates of vigor, classification for storage and determination of genetic parameters in germination characters, three experiments were performed in the laboratory of the Center for Native Seeds of Amazonas. Experiment 1 was performed in a germination chamber at a constant temperature of 30 °C. In experiment 2, the seeds were submitted to a constant temperature of 35 °C. In experiment 3, after 5 months of freezing the seeds were subjected to a constant temperature of 30 °C. The experimental design was completely randomized, consisting of 20 progenies, 4 replications and 25 seeds per plot. The germination characteristics evaluated were Germination Percentage (GP), Germination Speed Index (GSI), Average Germination Time (AGT) and Germination Synchronization Index (GIS). Genetic and phenotypic variances and correlations, broad sense heritability and gain by direct selection were estimated. The population presents desirable dendrometric characteristics for selection of seed carriers. O. discolor seeds exhibit orthodox behavior. The weight of one thousand seeds confirmed pattern of seeds classified as very small. The moisture content of the seeds does not exceed 11%. Seed lots presented low vigor due to colonization of endophytic fungi of various genera during the seed germination process. O. discolor progenies showed significant genetic variability for most of the traits evaluated. The matrices 2, 7 and 16 have good germination characteristics for all temperature conditions tested, being indicated for conservation programs, breeding and seedling production. Eighteen O. discolor seeds are sufficient for biometric analysis with a minimum accuracy of 95% in genotype selection.