Morfometria de frutos e sementes e germinação de carobinha (Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença), após o armazenamento

Abstract

This study aimed to evaluate the morphometry of fruits and seeds of Jacaranda decurrens subsp. symmetrifoliolata ("carobinha") and the effect of temperature on the germination of seeds that were stored in environment without controlled temperature and relative humidity. The study was carried out at Seed Laboratory of Federal University of Grande Dourados, Mato Grosso do Sul, Brazil. For a sample of 120 fruits and 550 seeds, the following variables were determined: length, width and thickness, besides the number of seeds per fruit and fruit biomass. Germination was studied after three seed storage periods (120, 480 and 720 days) at environment temperature and four germination temperatures: three constant temperatures (18, 25 and 30°C) with continuous light, and one alternating temperature, 20-30°C, with 12-hour photoperiod. Experimental design was completely randomized, in 3 × 4 factorial schemes, with four replicates. The variations in the measures of fruits and seeds evidence a high genetic variability in the population. The seeds stored for 120 days and subjected to germination test at 25°C resulted in 69.4% germination and germination velocity index - GVI of 0.983. At 30°C, constant temperature, and 20-30°C, alternating temperature, germination was 63.9% and 63.8% while GVI was 0.486 and 0.413, respectively. At 18°C, germination was slow and lower, 27.7%, and GVI was 0.119. Seeds stored for 480 and 720 days did not germinate. Based on the physiological behavior of seeds, it is possible to classify Jacaranda decurrens subsp. symmetrifoliolata as an intermediate species (between orthodox and recalcitrant).