Influência da temperatura e regime de luz na germinação de sementes de janaguba (Himatanthus drasticus (Mart.) Plumel.)

Abstract

This study aimed to evaluate the influence of the temperature and light on the germinative behaviour of janaguba (Himatanthus drasticus)seeds, with the experiments being conducted at the Laboratory of Seed Analysis of the Federal University of Ceará. To analyse percentage, velocity and average time of germination, the treatments consisted of four different temperatures (20ºC, 25ºC, 30ºC e 20–35ºC) and three different light expositions (constant dark; 8 h of light plus 16 h of dark; and constant light). The treatments consisted of 200 seeds, with four repetitions of 50 seeds each, sown on a Germitest towel paper, displayed inside Petri dishes, and maintained for 20 days in germination chamber. A completely randomized 3x4 factorial design (three light expositions x four treatments) was used. The Tukey's Test at 5% of probability was used to compare the obtained averages. The janaguba seeds were shown to have neuter photoblastism. The better conditions for janaguma seed germination are temperatures of 20 and 25ºC combined with constant dark and light/dark, constant temperature of 30ºC and alternated temperature from 20 to 35ºC combined with intermittent light/dark. The constant temperatures of 25 and 30ºC plus constant dark led to the greatest indexes of velocity of germination and caused the reduction of the germination average time.