Great Falls daily tribune., 1920-04-05
PLANT LIFE DEPENDS
MOST ON LIGHT, NOT
TEMPERATURE, CLAIM
Government Experts Discover
Revolutionary Principle by
Greenhouse Experiments.

Washington, April 4.-Government
agricultural experts have discovered that
plant life seems to depend on light
rather than temperature for nourish-
ment and may be controlled by regulat-
ing the hours Of light and darkness.
The principle is revolutionary, but it
rests on actual experiments in which
jected to alternate periods Of light and
darkness in carefully determined pro-
portions could be brought to maturity
at any time of the year
The discovery may be Of the highest
Importance in the future planning Of
cropping systems for different regions,
it is declared.
Greenhouse experiments" says the
announcement by the department of ag-
riculture, prove that the Towering and
fruiting period of practically any plant
can be made to take place at any time
of year by darkening the greenhouse
too long, or by lengthenins the day by
artificial light if the day is too short.
Have tho Daylight.
Spring flowers and spring crops
happen to be spring flowers and spring
crops because the days at the season
Of their Towering and fruiting have the
II.
Eventually it may be found, accord
ing to w. w. Garner and II. A. Alard
scientists, in the bureau Of plant indus
try who conducted exhaustive expert
ments, that the animal organism also is
capable of responding to the stimulus of
even day length. They believe that the
migration of birds may be an illustration
on the ground that direct response to
such stimulus would be more in line
with modern biological teachings than
theories which assume that birds .'Ko
south as a matter of instinct
Experiments were conducted with
conclusively that too little 'seep'' or
in other words, too many hours Of day.
light, would prevent many plants from
ever reaching the Towering and fruit
ing stage.
Even Bearing Type.
1t was found also that the plants
would not reproduce except when expos
ed to favorable length of day, although
too much daylight for Towering and
frulting might stimulate profuse vege-
tative growth. A length of day fav-
orable both to reproduction and growth
results in the lever bearing" type of
fruits.
BY employing dark chambers the
scientists shortened or heightened the
life cycle Of plants and caused some of
them to complete two cycles in one
season.
=, Temperature appeared to exert no in
f!ucnce in the tests. A striking illustra-
ton OF relative unimportance of tenn
perature was given in the fact that the
plants kept in the dark for part of
the day, underwent in mid summer. the
changes that in nature come in the fall
and that heretofore have been attrib-
uted to lower temperatures. This was
true even when the dark houses regis
tered higher temperature than the
outside atmosphere.
Is Potent Factor.
Iris kept in artificial light for IS
hours a day bloomed in two months.
while others in the same temperature
but without artificial extension of the
day required months longer.
The length of the day, the depart
ments announcement said, ''is proved
to be a most potent factor in determining
the relative proportions between the
vegetable and fruiting parts Of many
crop plants. Indeed, fruiting may be COM
pletely suppressed by a day too long or
TOO snort. This new principle undoubted-
y explains the erratic behavior Of which
has been observed with many crops
when they shifted to different latitudes''.
The experiments are said to explain
why many plants grow must luxuriantly
near the northern limit Of their range
where the long day permits maximum
growth before the short day
intervenes to start reproduction.