Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1920-08-24
L;oht Effects OF, Plant Life


IsCovERIEs recently made by the ma
tional Bureau of Plant Industry show
49, that light exerts a more peculiarly in
teresting and decisive influence on plant oe-
velopment than hitherto has been supposed.
Too many hours of sunshine, it. appears may
prove as unfavorable as too few, not neces-
sarily as matter of temperature put
through the effect of the light itself. On
the principle thus worked out it is SAID that
the Towering and fruiting of divers plants
can be fastened or retarded, and brought to
pass in any season if the light is properly reg
ulated. Thus violets can be made to bloom IN
midsummer by keeping them in the dark ex-
cept for the number OF hours OF daylight TO
which they are accustomed in early spring;
and in the same way flowers and vegetables
which ordinarily must bide autumns COM
ing can be induced to much speedier matur-
ity. That it is light, not temperature, which
controls in these cases is proved by expert
ments in which special care was taken to
keep the temperature for the plants In the
dark enclosures as high as for those outside.
DR.. W. w. Garner and DR.. W. A. Allard,
to whom the country is indebted for these
interesting and potentially valuable findings,
point out. that "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 proper num-
Der of hours of light" Likewise the flow
ers and crops of summer require longer
light period, and those OF autumn shorter
one. 1t appears, moreover, that "a length
of day which is unfavorable to reproduction
may be favorable to growth" under which
condition the plant will vegetate luxuriant-
ly but bring forth no fruit Where the
length of day is favorable both to vegetative
growth and to reproduction we have the
lever bearing types. An experiment with
soy beans is thus reported "For the test
plants the day shortened by several
hours; that is, they were exposed to the
light only from ten o'clock in the morning
to three o'clock in the afternoon. They were
| first placed in the dark house on May 20.
Control plants, otherwise treated exactly
like the test plants were, were left exposed
to the light from dawn till dark. The first
blossoms appeared on the dark-house plants
on June 16. No blossoms have as yet ap-
peared on the plants that were left in the
light all day. These plants require short
day and long night for Towering and seed
bearing. In tests with other plants just the
opposite was found to be true. The plants
| that were left in the light all day did not
grow luxuriantly, but produced flowers and
| seed, while those that were kept in the dark
| a part of the day made abundant growth, but
made no seed, or else were greatly retard-
! ed in producing seed Here again the scien-
| lists observed that, except for extremes Of
! heat or cold temperature seemed to exert
relatively little influence. plants kept in
| the dark for part of the day underwent,
| in midsummer, the changes that in nature
come in the fall and that always have been
attributed to lower temperatures''-this be-
ing the case even when the temperature for
the darkened plants was higher than that out
! of DOOR.
! Delvings and discoveries like these seem
to fix thu mind of man as sovereign over
nature, youngest of her children though he
is. He rises superior to her seasons man
dates, frightening or shortening the life
cycle of her plants and bringing them by a
thousand wondrous ways to the will of his
royal art Yet, after all, it is as the old
king said to Shakespeare's Perdita when they
talked of grating flowers:
"This is an art
Which does mend nature,-change it
! rather; ...
| But the art itself is natures"