Morfologia de sementes e plântulas, temperaturas na germinação e armazenamento de Eriotheca gracilipes (K. Schum.) A. Robyns

Abstract

Eriotheca gracilipes is a Cerrado native tree with potential for landscaping and recovery of degraded areas. The objectives of the study were to characterize and describe morphologically the seeds and seedlings of E. gracilipes, verify the germination at different temperatures and the storage of seeds in different types of packages and time. For the description of the biometry, a sample of 50 seeds was randomly removed from a batch of 1500 seeds and the length, width and thickness of the seeds were evaluated. In the characterization of the germination and the morphological description were used 100 seeds of the same batch, in four replicates of 25 seeds, placed on a roll of paper. The variables observed were: seed form, tegument color, color, position and length of cotyledons, length and color of roots and shoot, diameter and length of epicotyl and protophyll during 34 days . To evaluate the effect of different temperatures on germination of E. gracilipes seeds, the experimental design was completely randomized with treatments of eight temperatures (5, 10, 15, 20, 25, 30, 35 and 40 oC) and four replications. The variables analyzed were percentage of germination and seedling formation, and average time of germination and seedling formation, fresh and dry mass of the aerial part and roots. In the storage of seeds the treatments consisted of two types of packaging, waterproof (aluminum) and one permeable (paper), six storage times (60, 120, 180, 240, 300 and 360 days) and four replications, totaling 48 experimental plots. The experimental design was completely randomized in a double factorial scheme. The variables analyzed were percentage and mean germination time. Data were submitted to analysis of variance at 5% probability by the F test, polynomial regression analysis and tukey test. The description of the morphological seeds characteristics of E. gracilipes allows to classify them as spherical, striated, brownish-brown in color with a fine tegument. The E. gracilipes have fast germination, hypogean phanerocotonar and with cotyledon not symmetrical and different functions with reserve cotyledon larger than the cotyledon foliaceus. Seedlings can be used to identify the species and have heterofilia. In the Cerrado of the southern region of Mato Grosso (Rondonópolis), the recommended temperature for the germination and seedlings formation of E. gracilipes is 30 ° C. Extreme temperatures, below 10 ° C and above 40 ° C, are unfavorable for the species of the region. The seeds of E. gracilipes stored in paper or aluminum packaging, during the period of 12 months, maintain high percentages of germination. The permeable paper package is superior in vigor than the aluminum package. The present study supports future research on species recognition, germination and storage of E. gracilipes.