Aspectos ecofisiológicos da germinação de sementes de três espécies arbóreas medicinais da caatinga

Abstract

Despite the intense use of medicinal plants in Brazil, and this knowledge be restricted to know people, the scientific community has gradually interesting to recognize in and incorporate these practices. However, despite the importance of medicinal species, few studies have been conducted on the ecophysiology of germination or methods of propagation of these species. Due to lack of information in The Rules for Analysis of Seeds (Brazil, 1992) about the methodology for assessing the quality of seeds of medicinal tree species such as red angico (Anadenanthera colubrina (Vell.) Brenan var. colubrina, imburana de cheiro smell (Amburana cearensis (Allemão) A.C. Smith A.C. Smith) and Quixabeira (Sideroxylon obtusifolium (Roem.& Schult.) T.D.Penn.), this study aimed to establish procedures and methodology for safe evaluation of physiological quality of seeds of these species and initial growth of seedlings. The pre-germinative treatments were used (chemical, mechanical and thermal scarification) to break dormancy of seeds of S. obtusifolium. The seeds of A. colubrina (Vell.) Brenan var. Colubrina and Amburana cearensis (Allemão) A.C. Smith were submitted to different constant (25ºC and 30ºC) and alternate temperatures (20-30ºC and 20-35ºC) using different substrates (vermiculite, coconut powder, sand, sugar cane bagasse, waste of sisal and peat).After determining the best substrate and temperature for seed germination and initial growth of seedlings of these species, were tested different systems of light (light and dark continuous and photoperiods of 8-16h and 12-12h) to determine the best time of exposure for the germination and initial development of the species. The sulfuric acid for 30 minutes was effective to overcome the mechanical resistance of the skin, providing the best results for germination and early growth of seeds of S. obtusifolium. In the study of the germination and initial development of A. cearensis, because of the high performance achieved in most parameters measured, it is recommended the use of the constant temperature of 30ºC and alternated of 20-30ºC into peat and vermiculite. The constant temperature of 30 ° C combined with vermiculite and coconut powder, and alternated temperature of 20-30ºC in interaction with the vermiculite can be shown as optimal for the germination of A. colubrina (Vell.) Brenan var. colubrina, because they offer better germination performance. The seeds of A. cearensis and A. colubrina (Vell.) Brenan var. Colubrina showed quantitative positive photoblastism. The exposure to continuous light and to the photoperiod of 8-16h and 12-12h favored the seed germination and initial growth of seedlings of both species.