Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1920-04-06

WASHINGTON, April 3.-Govern-
ment agricultural experts have dis
covered that plant life seems to de-
pend on light rather than temper
allure for nourishment and may be
controlled by regulating the hours
of light and darkness.
The principle is revolutionary, but
it rests on actual experiments, in
plants subjected to alternate periods
of light and darkness in carefully
determined proportions could be
brought to maturity at any time Of
year.
Greenhouse experiments" says
an announcement by the department
of agriculture, prove that the flower
ing and fruiting period Of practi-
cally any plant can be MADE to take
place at any time of year by dark
ening the greenhouses in the morn
ing and evening if the day is too
long, or by frightening the day By
artificial light if the day is too
short.
Spring flowers and spring crops
happen to be spring flowers and
spring crops because the days at the
season of their Towering and fruit
ing have the proper number of hours
of daylight"
The discovery may be of the high
est Importance in the future plan
ming of cropping systems for DIFF
ferent regions. Eventually it may
be found, according to. w. w. Gar
ner and H. A. Allard, scientists in
the bureau of plant industry, who
conducted exhaustive experiments,
that the animal organism also is
capable of responding to the stimu-
lus Of certain day lengths. They be-
lieve that the migration of birds
may be an illustration on the ground
that direct response to such slim
illus would be more in line with
modern biological teachings than
theories which assume that birds go
south as matter Of instinct
Experiments were conducted with
a large variety of plants. 1t was
shown conclusively that too little
sleep" or in other words, too many
hours of daylight, would prevent
many plants from reaching the flow
ering and fruiting stage.
Too Much Daylight i
It was also found that plants
would not reproduce except when ex-
posed to a favorable length of day.
although too much daylight for
Towering and fruiting might stimu-
late profuse vegetative growth. \
length of day favorable both to re-
production and growth \resu1ts in
the "ever-bearing' type of fruits.
By employing dark chambers, the
scientists shortened Or heightened
the life cycle of plants and forced
some of them to compete two
cycles in one season. Violets, which
L urally bloom only during the
comparatively short days of spring,
when covered with light proof boxes
for time were made to bloom again
ing the summer. Biloxi soy
beans exposed to the light for only
five hours a day lowered nearly
three months earlier than plants left
in the light all day, but attained only
about one-eighth the height.
Temperature appeared to exert no
influence in the tests. A striking il
lustration of the relative unimport-
ance of temperature was given in
the fact that plants kept in the dark
for a part of the day, underwent in
midsummer the changes that in
nature come in the fall and that
heretofore have been attributed to
lower temperatures. This was true
even when the dark hours registered
a higher temperature than the out
side atmosphere.
Iris kept in artificial light for 10
hours day bloomed in two months,