Arizona republican., 1920-04-04
REPORT PLANT LIFE
 CAN BE CONTROLLED
 BY MEANS 0F LIGHT
Department of Agriculture Scientists Make Impor- tant Discovery that Light, Not Temperature, Regu- lateS Life of Plants

WASHINGTON. April s.-Govern. ment agricultural experts have discoy.
 cred that plant life seems to depend
 on light rather than temperature for
 nourishment and may be controlled by regulating the hours of light and dark ness.
 The principle is revolutionary. but it
 rests on actual experiments in which
 1t was demonstrated that plants sub | Jected to alternate periods of light and ! darkness in carefully determined pro- ! portions could be brought to maturity
 at any time of the year.
 he discovery may be of the highest importance in the future planning of cropping systems for different regions, if is declared I- Green house experiments" says the
 announcement by the department of
 agriculture, prove that the Towering
 and fruftfng period of practically any
 plant can be made to take place at any
 time of year by darkening the green house Tn the morning and evening if the day is too long, or by lengthening 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 day is at the season of their Towering and fruitiug have light
 Same Rule May Affect Animals
 Eventually it may be found. accord ing to w. w. Garner and H. A. Allard, scientists in the bureau of plant in- dustry, who conducted exhaustive ex- perlments, that the animal organism also is capable of responding to the 1 stimulus of certain day lengths. They | believe that the migration of bird may be an illustration on the ground that | dlrect response to such a stimulus | would be more in line with modern bi- | ologica1 teachings than theories which | assume that birds ''go south" as mat ter of instinct.
 Experiments were conducted with a large variety of plants. It has shown conclusfvely that too little sleep" or Tn other words too many hours of day lisht, would prevent many plants from reaching the Towering and fruiting stage.
 It was found also that plants would not reproduce except when exposed to favorable length of day, although too much daylight for Towering and fruit ns might stimulate profuse vegetative growth A length of day favorable both to reproduction and growth re- suits in the lever bearing" type of ruits
 No Effect From Temperature
 By employing dark chambers the chemists shortened or 1engthened the fife cycle of plants and caused some f them to complete two cycles in one eason.
 temperature appeared to exert mol in the tests. A striking illtis- ration of the relative unimportance of emperature was given in the fact that iants kept in the dark for a part of | ne day, underwent in midsummer the nanges that in nature come in the | III and that heretofore have been at 'ibuted to lower temperatures This as true even when the dark houses sgistered higher temperature than le outside atmosphere.
 The length of the day." the depart lent's announcement said, sis proved ) be the most potent factor in deter lining the relative proportions be- veen the vegetable and fruiting parts many crop plants. Indeed, fruitine ay be completely suppressed by al " too long or too short. This new 'inciple undoubtedly explains the er- tic behavior which has been observed '