Seed size and cold stratification affect Acer negundo and Acer ginnala seeds germination

Abstract

The aim of this work is to determine how the germination of seeds of the invasive tree Acer negundo depends on the period of cold stratification under the snow and the duration of stratification in the air on the branches of the trees. For comparison with A. negundo, we used seeds of Acer ginnala, introduced but not invasive tree in the Middle Urals. The period of stratification in the air modeled by collecting seeds in October and December. The duration of cold stratification under the snow was 0, 1, 2, 3 and 4 months. We hypothesized that the duration of stratification in the air did not affect the germination of A. negundo and A. ginnala seeds. Cold stratification under the snow had a positive effect on seed germination of both species. The best seed germination of A. negundo and A. ginnala was after 4 months of cold stratification under the snow, the germination rate differs: in A. negundo 12 ± 4% (small seeds) and 79 ± 7% (large seeds), in A. ginnala – 1 ± 2% (small seeds) and 18 ± 4% (large seeds). In both species, large seeds germinated at 7 to 18 times more intensively than small ones. In A. ginnala case, even after cold stratification under snow for 4 months, no more than 22% of the seeds germinated. The germination of A. ginnala seeds was 4–5 times lower than that of A. negundo seeds.