The aim of this study was to estimate the genetic parameters of Ormosia excelsa seeds based on germination traits, at different temperatures, in order to facilitate the selection of superior varieties of seeds for producing seedlings. Twenty six progenies collected in the municipality of Autazes (state of Amazonas, Brazil) were evaluated. The experiment was completely randomized, with four replications and 25 seeds per plot, totaling 100 seeds per progeny. The germination rate, mean germination time and the synchronization and speed germination indexes were determined at the temperatures of 30 and 35 °C. Seedling development was also evaluated under nursery conditions. The progenies of O. excelsa showed significant genetic variability for all traits. Both temperatures proved to be effective in producing germination close to 87%. Germination began between 1 and 4 days after sowing. However, for greater efficiency in the selection of superior progenies, each environment should be considered individually. The high heritability values obtained (> 65%) and the high genetic correlation favorable for selection, among all traits, resulted in significant gains according to the selection process used. Our results indicated that determining superior progenies for height and number of leaves was possible based on a single evaluation. The fact that 100% of seedlings planted in the field survived promotes a promising outlook to set up commercial nurseries for the species.
Additional keywords: pau-pretinho, plant disease
________________________________________________________________________________The forest species popularly known as "pau-pretinho" (Cenostigma tocantinum Ducke) is one of the most used in urban arborization of the municipality of Manaus, Amazonas (Brazil). It is a native species to the Amazon and has low susceptibility to attack by pests and pathogens (GARCIA; MORAES; LIMA 2009). Throughout the year 2018, symptoms were observed on the leaves positioned in the lower third of the crown of C. tocantinum trees. The symptoms were characterized by areas of light brown color in the center and dark brown edges observed on leaves. The symptomatic trees were located on campus of Federal University of Amazonas (UFAM), in Manaus, where the temperature and rainfall ranged from 24°C to 33°C, and 113 mm to 335 mm in this period. Small fragments (2 to 3 mm) of symptomatic leaf tissues were surface disinfested, plated on potato dextrose agar (PDA) amended with 0,25 g.L -1 of chloramphenicol, incubated at 25°C and hyphal tips were transferred to fresh PDA plates. The monoculture mycelium was initially white, gradually darkening and becoming dark brown after 14 days (Figure 1). No presence of conidia in PDA culture medium was observed after 20 days. The pathogenicity test was conducted on C. tocantinum seedlings. Leaves were inoculated with mycelial discs. After inoculation the plants were sprinkled with the mixture of water and fungal mycelium and kept in plastic bags to maintain moisture. The plant control was inoculated with agar disc, sprayed with water, and kept in plastic bags. Symptoms similar to those observed in the naturally infected plant were observed in the C. tocantinum seedlings after 15 days (Figure 2). The symptomatic leaves were placed in a humid chamber and after 48 h spores (measures) were observed at the apex of the conidiomas. The pathogen was reisolated from the lesions, and their identity has been performed by molecular methods. The 3 Kbp ribosomal (SSU, ITS and LSU) and beta-tubulin (TUB2) regions (acession number: MK299422, MN067841), were amplified and sequenced using primers NS1-NS8, ITS1, ITS4, Uni-R primers and T1-T2 (FELL, 1993;O'DONNELL; CIGELNIK, 6
/agrariacad Efeito de diferentes volumes e tipos de recipientes no crescimento inicial de mudas de Ormosia excelsa Benth. Effect of different volumes and types of containers in growth seedlings initial Ormosia excelsa Benth.
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