Germination ecology of Trachycarpus fortunei (Arecaceae), a species with morphophysiological and shoot dormancy

Abstract

Beyond strong inference that most of the 2600 known species of Arecaceae produce diaspores with an underdeveloped embryo and therefore have morphological dormancy (MD) or morphophysiological dormancy (MPD), little is known about the specific dormancy class or sub-class and how dormancy-break occurs under ecological conditions. Here, we found that mature seeds of Trachycarpus fortunei (Hook.) H.Wendl. collected at the time of natural dispersal had an underdeveloped embryo that was 10% of total seed length. No diaspores germinated over a wide range of temperatures in either light or darkness. Cold stratification at 4 °C for one, two, and three months or treatment with 100, 500, and 1000 ppm gibberellic acid (GA3) improved germination percentages, with three months cold stratification or 1000 ppm GA3 resulting in highest germination. The embryo grew inside the seeds during cold stratification; however, warm stratification did not improve germination. Therefore, seeds of T. fortunei have intermediate complex MPD. Cold-stratified seeds that were moved to spring conditions (night and day temperatures of 15 and 20 °C, respectively) had cotyledonary petiole (CP) elongated, but leaves developed only when the CP elongated seeds were moved to summer temperatures (night and day temperatures of 25 and 30 °C, respectively), suggesting the presence of shoot dormancy. The seedlings are remote-tubular type. This is the first report for Arecaceae indicating the presence of complex MPD.