A quantitative relationship is shown to exist between the chlorophyll content of soybean and Valencia orange leaves and their percentage reflectance of light of wavelength 625 mmicro as measured by a colorimeter with reflectance attachment.
IntroductionTwo types of experimental method have been employed by investigators in the field of photoperiodism. In the one case the experiments have been conducted during the long days of summer and the natural daylength used for the long day treatment, with the short days produced by moving the plants into dark chambers after a certain number of light hours. In the second type of experiments the investigations have been carried on during the short days of winter and the natural daylength used for the short day period, the long days being produced by the addition of artificial radiation.It might be questioned as to whether the results of the two experimental methods are comparable and whether both involve the same group of physiological processes, since the conditions of radiation for the two differ so widely. That those conditions used in the greenhouse during the winter do not simulate the conditions under which the plant would respond during its natural growing season must be recognized. This is especially true in regard to light intensity and spectral energy distribution.In the first paper published by GARNER and ALLARD (1) on the effect of the photoperiod on the flowering of plants, it was shown that typically long day plants became reproductive and short day plants assumed the vegetative state when they were subjected to naturally short winter days artificially lengthened with relatively low intensity incandescent lamp radiation. TINCKER (14) obtained similar results with several long and short day plants when he used 5 foot candles of visible radiation to supplement the natural daylight period. TINCKER (15) conducted experiments
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.