The Brattleboro daily reformer. (Brattleboro, Vt.) 1913-1955, 1920-12-04
LIGHT AND PLANT LIFE.
Sunshine Supposed to Be Necessary But
Possible to Have Too Much.

1t has been agreed by all sorts of people
from farmers to scientists that sunlight
is necessary for normal growth of most
kinds of plants. The farmers discovered
| it through the appearance of sprouting
tubes in the cellar and the scientists by
experiments which brought about like
results. but now the scientists have gone
a step further and have learned that it is
possible for plants to have too much day
| light, that is TO say, too many hours of
sunlight in comparison with the number
| of hours of darkness.
That explains. for instance. why some
| flowers blossom early in the spring while
others require a long period of light be-
| fore their efioreScence, but it also appears
! that the intensity of the light has less
significance upon the growth of the plant
/ than has been supposed. Greenhouse eX
perimentS have shown that the Towering
and fruting period of any plant can be
brought at any period Of the year by dark
ening the greenhouse in the morning and
evening if the day is too long or by
/ lengthening the day by artificial light if
the day is too short.
| Violets, for example. bloom during the
| short days of early spring, but if the
plants are put in lightproOf boxes at night
and not uncovered until well after sun
rise the plants can be forced to bloom
again in the summer. Thus spring flow
ers and spring crops are such because the
{ y -
|fruiting, have the proper number of day
| light hours So, too, the early summer
/ flowers and crops IffuSt have a longer Pc
Rod Ofsdaylight.' The plant cannot attain
to reproduction except when-it is exposed
to a favorable length of day, but length
of day which, Is unfavbrable TO reproduc-
ton may be favorable to growth and under
SUCH cppditions the plant continues its
| yeget ative Development but produces no
| fruit, j., . --..s.. ... .... segst
| Tests have been made with soy beans,
( tobacco. wild aster. climbing Mmpweed,
beans, ragweed, Tadish carrot, lettuce
hibiscus, goldenrod. spinach, iris, buck
wheat and various other plants and all
responded to it. Soy beans were exposed
/ to the light from 10 a. III. to 3 p. m. from
/ May 20 to September 4, while other bean
Iplants terminated at the same time were
given the normal amount of daylight. The
/ first blossoms appeared on the darkened
Iplants~ on June 16. but none appeared on
those that We're left in the light until
September f. The dark house plants at
/ the latter date were six to seven inches
/ high. while those having full daylight
were 81 or IS inches, showing that the
plants required a short day and long
night for Towering and seed bearing.
| The length of day. it has been found.
is more important than temperature for
the results were the same when the tenn
pcrature was higher in the dark house
3 man III Niit open anu pants tlldl NGIt
! left in the dark for a part of the day
underwent in midsummer the change that
in nature comes in the fall and have been
attributed to lower temperature.
These scientists are discovering some
thing for the theory which their expert
lments develops shows why many plants
grow best near the northern limit of their
range for the long northern day allows
them to attain their maximum growth be
fore the shorter day checks growth and
starts a reproductive process 1t may
be found. so these scientists think. that
the animal organism responds to the
stimulus of certain day lengths and that
the migration of birds is an effect of it.
These men are increasing knowledge
Hartford COurant.