Geoscience Reference
In-Depth Information
Environment stress
Biotic
Abiotic
Stress response
Resistance
Susceptibility
Avoidance
Acclimation
Senescence
Survival
Growth
Death
Survival
FIGURe 14.3
The effect of environmental stress on plant survival. (Adapted from
Hopkins, W. G., Hüner, N. P. A. 2009.
Introduction to Plant Physiology
, 4th ed.,
John Wiley Sons, Inc., Hoboken, USA.)
prevent flowering, seed formation and induce senescence that
leads to plant death. Such plants are considered to be suscep-
tible. Some plants escape the stress altogether, such as ephem-
eral, or short-lived, desert plants.
Ephemeral plants germinate, grow and flower very quickly
following seasonal rains. Thus, they complete their life cycle
during a period of adequate moisture and form dormant seeds
before the onset of the dry season. In a similar manner, many
arctic annuals rapidly complete their life cycle during the short
arctic summer and survive over winter in the form of seeds.
Because ephemeral plants never really experience the stress
of drought or low temperature, these plants survive the envi-
ronmental stress by stress avoidance. Avoidance mechanisms
reduce the impact of a stress, even though the stress is present
in the environment. Many plants have the capacity to tolerate
a particular stress and, hence, are considered to be stress resis-
tant. Stress resistance requires that the organism exhibit the
capacity to adjust or to acclimate to the stress.
Short-term
acclimation
The
short-term processes
involved in acclimation can be initi-
ated within seconds or minutes upon exposure to a stress, but
may be transient in nature. That means that although these
