The strategies of plants germinating in the optimal time
Our results showed plants that geminated in late spring performed the
best in total mass and reproduction among all treatments, and they had
the highest stem mass and allocation, and the lowest leaf allocation. It
is reported that early emergence can improve the performance and
survival of plants (Abe et al., 2008; Afonso et al., 2014; Bianchi et
al., 2019; Cogoni et al., 2013; Verdu´ & Traveset, 2005), due to the
profits from a long growing season for growth and reproduction (Donohue
et al., 2010; Stratton, 1992). Meanwhile, the climate and soil
conditions in late spring should also be more favorable for rapid
biomass accumulation, making them less likely to expose to environmental
hazards than those germinated in earlier time of spring. Consequently,
they can optimize performance in relatively more favorable environmental
conditions, leading to an extensive vegetative growth and improved
reproduction. In this term, plants that germinate early can have a
strong competitive advantage over those germinate late, especially at
high population densities (Miller et al., 1994; Orrock & Christopher,
2010). The planting density applied in this study was a little high
(plants were sown with an inter-plant distance of 10 cm), which may
cause some extent of competition, inducing additional stem elongation,
especially for those germinated earlier in spring and late spring and
when they grew to larger plant sizes.
The timing of germination determines the environmental cues plants
expose to, such as day length, temperature and water availability, which
influence the responses of life history traits (Huang et al., 2016;
Wilczek et al., 2009). Plants can perceive and transmit the signals of
changing photoperiod and temperature (Zhou et al., 2005), to promote
time emergence, growth and reproduction to coincide with favourable
conditions (Andrés & Coupland, 2012; Blackman, 2017). It suggests they
are able to judge the environmental changes by these signals, and
determine which strategy to use in dealing with the circumstances
indicated by the environmental cues. Consequently, when they did not
germinate within the optimal period, plants may still be able to adjust
their growth strategy in exposure to unfavorable conditions due to
advanced or delayed germination.