Aspects of the Physiology of Seed Dormancy in Relation to its Implications for Agriculture

BENECH-ARNOLD R.L.; RODRÍGUEZ, M.V.; BATTLA, D.

Encyclopedia of Sustainability Science and Technology

SPRINGER

Año: 2012;

I) Introduction A seed can be declared to be dormant when it fails to germinate despite it is given all the ?proper? conditions (that is, enough water and appropiate temperature) for germination to happen. Assuming that we are talking of a living seed (a dead seed would not germinate either), then why does it not germinate? Will it ever germinate? These type of questions were probably first asked in despair by farmers about 10,000 years ago, while staring at their useless recently harvested grains that would not give way to a new crop or allow malting for beer (a process that also relies on germination). Despite historical human concerns with dormancy, this ?internal block to germination? has been positively selected throughout millions of years of evolution in most temperate species, and has obvious ecological benefits in the wild. The main apparent role of seed dormancy is to delay germination until a proper environment is encountered, for example, by keeping track with seasonal changes in temperature to avoid unfavorable conditions for plant establishment (Baskin and Baskin 1998). Within the life of most plants, the only chance to travel is as a seed.  After separating from the mother plant, the seed is moved by different means (wind, gravity, water, animals) until it is randomly located in a new microenvironment that may prove adequate or not for completing its life cycle. Once germination happens, the small plant will most probably remain attached to that spot until it is death. As a consequence of plants being sessile organisms, seeds have developed sophisticated mechanisms to collect information from the environment, and the resulting output is a vital decision: to germinate right away, or not (at least not this time, this place) until new environmental conditions that are good enough are finally met with.