Seed Coat Treatments Influence Germination of Taxodium mucronatum

Abstract

The range of Taxodium mucronatum Ten. (Mexican bald cypress) is declining rapidly, yet relatively little is known about the propagation of this valuable ornamental tree. The objective of this study was to determine whether seed coat treatments could enhance the germination of Mexican bald cypress. Seeds of Mexican bald cypress were collected from Las Cruces and the Gila National Forest, New Mexico. In one experiment, seed coats were knicked or left intact, then germinated on moist filter paper or flooded with water. In another experiment, seed coats from the Las Cruces provenance were treated with sulfuric acid, knicked, left intact, or removed (excised embryos) and germinated on moist filter paper. Knicked and moist seeds had a greater mean cumulative germination percentage (13.5 %) than intact and flooded seeds (4.2 %). Final germination percentage of the Las Cruces source was similar among knicked seeds, intact seeds, and excised embryos, but intact seeds took a longer time (15 days) to reach 50% of final germination percentage than did excised embryos (10 days) and knicked seeds (8 days). Seeds treated with sulfuric did not germinate. Results indicate seed coat pretreatments are needed to release physical dormancy and promote efficient germination of Mexican bald cypress.