Fig. 3 Estimated marginal means of minimal adequate GLMs on
germination of Musa seeds buried in Simulated-NHs in Belgium (a)
Binomial germination outcome; (b) mean germination time; (c)
synchronization index.
Effects of microclimate variables on seed germination
The effect of each microclimate variable on final germination percentage
was visualized (Fig. S3). These were then used to estimate breakpoints
on GLMs produced from binomial germination outcomes (Fig. 4). Results of
this show temperatures (at seed burial level) operate a threshold
mechanism, above which germination increases linearly (on the logit
scale), within the limits of temperatures achieved in simulated-NHs.
Therefore, for germination to occur mean soil temperature needs to be
above 19°C, maximum temperature above 23°C, minimum temperature has much
less of an effect. At the soil surface, the effect of mean temperature
is positively linear to an optimal 24°C after which germination is
reduced. The effect of maximum temperature is positive above a threshold
of 28°C. Germination increases with soil surface minimum temperature to
15°C, then the positive slope is less steep. Soil warming relates to
light intensity asymptotically (as described above); germination
increased above 1076 lux (mean). In relation to maximum light intensity,
germination increased to a breakpoint at 54000 lux, after which the
effect on germination is negative. Comparisons of AICs of these models
(Table S1) show at seed burial level the maximum temperature is the best
fit; at soil surface level mean temperature is the best fit, and mean
light intensity is a better fit than the maximum value during cue
periods.