Abstract
1. Ecologically meaningful seed germination experiments are constrained
by access to seeds and relevant environments for testing at the same
time. This is particularly the case when research is carried out far
from the native area of the studied species. 2. Here, we demonstrate an
alternative - the use of glass houses in botanic gardens as
simulated-natural habitats to extend the ecological interpretation of
germination studies. Our focal taxa were banana crop wild relatives
(Musa acuminata subsp. burmannica, M. acuminata subsp. siamea and M.
balbisiana), native to tropical and subtropical Southeast Asia. Tests
were carried out in Belgium, where we performed germination tests in
relation to exposure to sun and foliage-shading, seed burial-depth in
different heated glass house compartments, as well as seed survival and
dormancy release in the soil. We anchored the interpretation of these
studies by also conducting an experiment in a semi-natural habitat in
the species native range (M. balbisiana - Los Baños, the Philippines),
where we tested germination responses to exposure to the sun and shade.
Using temperature data loggers, we determined temperature dynamics
suitable for germination in both these settings. 3. In semi-natural and
simulated-natural habitats, seeds germinated in response to exposure to
direct solar radiation. Seed burial-depth had a significant but marginal
effect by comparison, even when seeds were buried to 7cm in the soil.
Temperatures at sun-exposed compared to shaded environments differed by
only a few degrees Celsius. Maximum temperature of the period prior to
germination was the most significant contributor to germination
responses and germination increased linearly above a threshold of 23°C
to the maximum temperature in the soil (in simulated natural habitats)
of 35°C. 4. Glass houses can provide useful environments to aid
interpretation of seed germination responses to environmental niches.