Métodos de superação de dormência em sementes de croada (Mouriri elliptica Mart)

Abstract

Croada seeds (Mouriri elliptica Mart.) Melastomataceae, a fruit-bearing species native of the cerrado (savannah-like vegetation), were submitted to the following dormancy breaking methods: pre-cooling at 5° C for 7 days; pre-heating in a oven air circualtion at 40º C for 7 days; chemical escarification in concentrated sulfuric acid for 5 and 15 min; soaking in boiling water for 5 and 15 min; soaking in gibbereli acid at 100 and 200 mg L-1 for 48 hours; soaking into distilled water for 24 and 48 hours; mechanical escarification with a sandpaper number 80 at teh upper aprt and opposed to the embryonary axis and control (seeds without any previous treatment). The seeds were put to germinate on a "germitest" type paper moistened with destilled water or 0.2% potassiun nitrate. Daily counts between the 2nd day after the establishment of the experiment till the stabilization, which took place on the 60th day, were performed. Seeds germinated faster when they were pre-soaked in gibberelic acid, independent of if placed to germinate on a water-moistened substrate or with a soultion of 0.2% potassiun nitrate, pre-soaked into water for 24 hours, on a water-moistened substrate, or independent of the substrate, and, pre-soaked into water for 48 hours or mechanical escarification and put to germinate on a water-containing substrate. Higher germination rates occurred in seeds pre-soaked into 100 or 200 mg L-1 gibberelic acid, on a substrate moistend with a 0.2% potassiun nitrate containing solution.