Methods of Enhancing Germination of Anacua Seeds

Abstract

Seed dormancy hampers establishment of anacua [Ehretia anacua (Teran & Berl.) I.M. Johnst.] in plantings for wildlife. We evaluated methods of enhancing anacua germination and causes of dormancy. Seeds were (1) scarified with 2.9 mol liter-1 H2O2 or 0.71 mol liter-1 NaOCl for 10, 20, or 30 minutes, or concentrated (18.0 mol liter-1) H2SO4 for 15, 30, 60, or 120 minutes; (2) rinsed with water for 12, 24, 36, and 48 hours; (3) treated with 0.1, 1.4, 2.9, and 4.3 mmol liter-1 gibberellic acid (GA); (4) treated with 0.02 mol liter-1 KNO3; (5) treated with dry heat (130 degrees C) for 3, 6, 9, 12, and 15 minutes, (6) mechanically scarified; and (7) moist prechilled at 3 and 7 degrees C for 2 or 4 weeks. Seeds were germinated in controlled environment chambers at 30 degrees C. Germination was not enhanced by chemical scarification or rinsing. GA (1.4 mmol liter-1) increased germination from 35% for controls to 61%. Mechanical scarification and dry heat enhanced germination of highly dormant seeds only. A 2-week moist prechill at 3 degrees C increased germination of intact seeds from 6% for controls to 36%. Percent and rate of germination were similar among seed sources. Apparent afterripening requirements limited germination at 2 months after harvest to 3%. This requirement gradually broke down until at 8 months after harvest, germination had increased to 40%. Our results indicated that treatment with 1.4 mmol liter-1 GA or higher concentrations, moist prechilling for 2 weeks at 3 degrees C, and storage for 8 months will increase germination of dormant anacua seeds.