THE SPIRIT
OF PLANTS - BALANCE
I found the
following article on a very interesting French blog, which I will have occasion
to quote other times, "Graines de Mane" (Seeds of Mane), devoted, as
its subtitle says, to popularization and debate about agriculture (https://www.grainesdemane.fr/2017/02/08/plantes-nont-tete-tourne/).
In this
case, it's a curious subject, insofar as this question is not usually asked.
Yet, as you
will be able to verify, this is an important question, and the similarities
with animal world are surprising.
"Plants don't feel dizzy
Often agitated by the wind, plants
remain standing. How do they do it? Researchers at INRA [French National
Institute for Agronomic Research] have identified mechanisms that allow plants
to maintain the balance.
The wind is one of the (many)
natural enemies of the farmer. In the event of too strong storms, plants can
overturn, that's to say lie down, to become non-harvestable in the end. Global
cereal yield losses are estimated at 10% due to storms. Despite this, plants
have a remarkable ability to stand, much more than us!
Shaked by the wind, the reed bends
but does not break. Charles and Francis Darwin had already highlighted in their
time the ability of plants to grow in a given direction. Thus, a plant always
grows towards light (phototropism) or gravity (gravitropism), causing its roots
to grow downwards and germinate upwards. Forcing a plant to grow horizontally
and it will always end going upward.
Plants also
have an inner ear
To understand the functioning of
the mechanisms of plants balance, let's stop for a moment on ours, governed by
the inner ear. In this, our balance is made by a so-called otolitic system,
which is a set of small pebbles caught in a sensitive gel. The deformation of
the eyelashes, due to the action of gravity on the pebbles, allows our inner
ear to locate the vertical. However, when we are in a merry-go-round, for
example, we lose the sense of gravity. Our inner ear is then incapable of
distinguishing the acceleration due to gravity, of other forces, such as
centrifugal force, for example.
Plants also have an equivalent of
the inner ear: the statocytes. The statocytes are cells arranged throughout the
stem of the plant, which contain small grains of starch called statoliths.
Until now, research has demonstrated a similar function of the statocytes to
that of the inner ear: the sedimentation of statoliths exerts pressure on the
statocyte wall and allows the plant to detect gravity. This idea suggests that
plants have a sense of balance comparable to that of humans and therefore they
are not able to distinguish the gravity of another force, the wind for example.
The pressure exerted on the statoliths would be the result of all the forces in
an undifferentiated way.
A more acute
sense of balance than humans?
Another hypothesis suggests that
it's not the pressure exerted by statoliths that allows plants to
"feel" gravity, but a sensor systems that detect the position of
small starch grains. This idea stems from recent research carried out jointly
by INRA, CNRS [French
National Center for Scientific Research]
and Blaise Pascal University. The researchers formed a carousel for plants,
consisting of centrifuges with two axes of rotation, as they exist for astronauts
training. They then subjected to centrifugal forces hundreds of plants, many of
them cultivated like wheat, lentil or sunflower. They studied, for long
periods, the growth of plants under these conditions, with a different angle
compared to the actual gravity.
The story does not say whether the
plants had fun in the carousel, but it shows on the other hand that they have
managed to grow by straightening independently to the intensity of the
centrifugal force they suffered. Plants thus can feel the verticality
independently of the other forces to which they are subjected, and this
permanently. The positioning of the statoliths, and not just the pressure they
exert, would allow the plants to detect their verticality. Even shaken by the
wind, plants would be able to keep their verticality.
Unlike us, they would not feel
dizzy.
These recent discoveries of balance
of plants mechanisms, can have very important applications in the decades to
come, especially in varietal improvement, to conceive crops less sensitive to
overturning. If this track should not make us forget that the overturning of
plants can also be due to other agricultural factors (too much nitrogen for
example), this is perhaps one of the many ways forward for securing yields
against the vagaries of the climate.
If you want to
learn more :
The perceptual feat of plants to
stay vertical (INRA) http://presse.inra.fr/Communiques-de-presse/Le-tour-de-force-perceptif-des-plantes-pour-se-maintenir-a-la-verticale
How plants stay straight, (Pour la
science) http://www.pourlascience.fr/ewb_pages/a/actu-comment-les-plantes-restent-droites-37804.php
»
Here is
another surprising characteristic which shows that the more one studies the plants, the less one finds a profound
difference between the vegetable and the animal world.
A sign to
call the vegans to more reason?
In
the end, science shows us that most animal characteristics are also present in
plants, although in a different way, since adapted to their particular
condition.
Picture: https://s-media-cache-ak0.pinimg.com/originals/54/6a/a5/546aa54c590add3d9ff95fd2ca663d14.jpg
Aucun commentaire:
Enregistrer un commentaire