Estabelecimento de protocolo para análise de germinação de sementes de Zizyphus joazeiro Mart

Abstract

Zizyphus joazeiro Mart. (Rhamnaceae) is a native forest species of the Caatinga Biome. It has a potential commercial value, with industrial, medicinal, ornamental and timber application. Thus, this research aims to establish protocols for germination analysis,methodologies for overcoming seed dormancy, as well as the avaluate effect of different substrates, light and temperature on the germination of seeds. The following pre-germination treatments were used to break the dormancy of Zizyphus joazeiro: immersion in concentrated sulfuric acid 98% for 30, 60, 90, 120 and 150 minutes; immersion in potassium nitrate (KN03) solution at a concentration of 0.2% for 120 minutes and 24 hours; immersion in solutions of gibberellic acid (GA3) at concentrations of 500 and 1000 mg/L, for 120 minutes and 24 hours; exposure to -15°C for 24, 48 and 72 hours; mechanical scarification of endocarps with sandpaper; removal of endocarp and immersion in potassium nitrate (KNO3) at a concentration of 0.2% for 120; removal of endocarp with immersion in gibberellic acid at a concentration of 500 mg L-1 for 120 minutes with damping of the substrate; immersion of seeds with endocarp in water at room temperature (25°C) for 72 hours; immersion of seeds with endocarp in water at 100°C for 1, 3 and 5 minutes; and endocarp crunching. The best results for overcoming dormancy were obtained when the endocarp was removed and the seeds put in a solution of potassium nitrate (KN03) 0.2% for 120 minutes and there was a damping of the substrate. The seed were subjected to different substrate(coconut fiber, on washed sand, through washed sand, on vermiculite and roll of paper), different temperatures (25°C, 30°C and 20-25°C), and in different light conditions (presence and absence). According to the results, can be recommend for the methods washed sand of 25ºC and 30ºC, in the absence of light, through washed of 30ºC, in the absence of light, vermiculite of 25º and 20-25°C, in the presence of light, roll of paper of 25º and 20-25°C, in the presence of light provide good germination performance of seeds of Zizyphus joazeiro.