| Show Sun Not Not- Needed by the Flowers ei Scientists Find They Grow as Well Under the Electric Light Washington The The affection of plants for tor the kindly sun so long proclaimed by iy observing poets appears to be a trifle exaggerated A rose can be made to grow and bloom under a yellow electric light or an artificial light of ot blue red or any other color and It will still be a rose and look just lust about tho the same as If It It had hud been kissed b by the gentle sunbeam Experiments In raising plants under colored light have been conducted Inthe In Inthe inthe the past and the experimenters have emerged from their weirdly colored greenhouse laboratories to report that under blue green or purple light plants failed tailed to develop normally But as ns Dr W. W W W. Garner of the Department of Agriculture and his associates associates as as- H. H A. A Allard and Dr R. R A. A Steinberg continued this remarkable work with the effect of light on plants they got around to the question of colored colored colored col col- col- col ored light with the Interesting results already mentioned Dr Garner and Mr Allard have already al- al already al ai- ready proved a revolutionary theory I w to account for the fact that chrysan- chrysan bloom In November No and common common common com com- mon Irises bloom In May and poinsettias poinsettias poin- poin bloom In December Temperature Tempera Tempera- ture had always alwa's been regarded as the controlling factor In this question of ot seasonal blooming And yet florists had tried to make cosmos bloom In off oft seasons In greenhouses by keeping the i temperature at a September level level level- with Ith no luck Length of Day Important The Tho Important factor which has liar been overlooked says Dr Garner Is the he length of ot the day When cosmos are exposed to light for tor the Ule number of ot hours that a September day would give them hem they make haste to bloom Plants may be Injured or benefited by changes In temperature and In the Intensity of light Some are very sensitive sensitive sensitive sen sen- to these factors But Dut In general general general gen gen- eral life habits of or plants do not depend depend depend de de- de- de pend on such uncertain conditions Every Svery first day of ot September Is the same length allowing for slight calendar calendar calendar calen calen- dar variations and plants have been under the Influence of or the unchanging cycles of ot light for tor thousands of years so 50 It Is not surprising that the plant world Is governed by them This theory has been tested by government government government gov gov- experiments on nearly varieties of plant life lire Including trees I wild and und cultivated flowers farm crops and weeds Varieties that bloom when the days da s 's are short are called by the experimenters e. short-day short plants and those that bloom under long light exposure exposure exposure ex ex- ex- ex are called long-day long plants By rolling trucks laden with specimens Into dark houses the day can be shortened shortened shortened short short- ened In some experiments and by lighting greenhouses at nt night the days can be lengthened for other tests At the government experiment farm tarm right now the scientists have among other exhibits poinsettias and chrysanthemums chrysanthemums chrysanthemums chrysan chrysan- In bloom In December they have such plants as Iris and coreopsis In full bloom The blossoms are normal normal normal nor nor- mal In all respects and some Borne are su- su su su- May Be Kept From Blooming Keeping a flower from blooming Is easy enough by the new light theory Some cosmos grew up from seed during durIng during dur dur- durI I ing the spring In a long-day long greenhouse greenhouse greenhouse green green- house that was Illuminated from sunset sunset sunset sun sun- set to midnight In June the plants were moved out of doors where they received only normal summer sunlight Not until October came and ond the days were the right length for cosmos to bloom did these specimens produce any blossoms The plants were then 15 feet teet high This Is the freakish sort of ot thing that sometimes happens when plants are arc brought to the United States from the tropics Often these specimens grow to ridiculous heights and never produce flowers or seed because the sunlight ration mUon Is 18 never just right for tor those processes One of ot the most striking proofs of the light theory theory- Is a specimen which has a cluster of or blossoms on one branch and no flow flowers ra on another One branch rach of ot the t e plant was Induced to o flower by y giving It the exact lIghtn light- light day n necessary whereas the other other branch was covered from the light during a a apart part of f each each day Both Doth branches got food and water from the same soil through the same stalk but tho the light rays ras affected only the spray I that was uncovered The other spray continued to grow normally but without without without with with- out producing buds From lengthening and shortening thedas theda's the days das for tor pl plants It s seems ems only a step stepto to eJ experimenting with ar artificial daylight daylight day day- light but Dr Garner found that this was quite a different proposition When the plants were exposed to light a afew afew afew few ho hours rs overtime each day very Tery weak electric light was adequate MIdday Midday Midday Mid MId- day sunlight may be equal to 10 I foot candles the foot the Intensity of standard candles at n a distance of one foot toot But nut for the tho lengthening of a aday aday aday day electric light equaling five or ten foot candles s was for foor most specimens sp r When hc no n sunlight ht at al all was given to specimens however It became n necessary necessary essary to use very bright electric lights With this stimulation plants behaved just as If It they had been out ont of doors If there are an any mysterious qualities peculiar to sunlight they do donot donot donot not seem to be necessary to plant growth |
