Liana and vine germination requirements in a subtropical forest zone

Abstract

Climbing plants may be classified as lianas (woody) or vines (herbaceous). This grouping is not taxonomic but is useful for functional ecology. We evaluated seed germination of three liana and four vine species from the Chinese subtropical forest zone. Seeds were collected from different environments (abandoned agricultural land, broadleaf forest, coniferous mixed forest) and seed traits characterized (seed fresh mass, seed shape index, water gain). Germination tests were conducted under different temperature regimes: 5/10, 10/20, 20/30, 25/35, 35/40 °C under light and dark conditions. Additionally, we tested the relationships of germination responses (germination percentage, mean germination times, and relative light-germination index) with seed traits. The two species from abandoned agricultural land (Glycine max subsp. soja and Ipomoea triloba) had impermeable seed coats and reached only intermediate values of germination percentage, from 20 to 40% in the tested temperatures, with little effect from light regimes. In the broadleaf forest, Ipomoea nil also had impermeable seeds, but reached 91% of germination under 25/35 °C. Seeds of I. nil were the largest ones (4.8 g per 100 seeds), and there was a positive relationship of seed mass with G%. Seeds of Kadsura longipedunculata (liana) had low G% under all tested temperatures, probably related to some dormancy type, which requires further investigation. Species from coniferous mixed forest were greatly affected by temperature regimes, and Coptosapelta diffusa (the smallest seeds) had also the most light-dependent germination. Light-germination index had thus a significant/negative relationship with seeds mass. Environmental factors may help to explain the distribution of seed traits in our study, but further research should examine a larger set of species to better understand regeneration ecology of climbing plants in contrasting ecosystems.