Relation of Carotinoid Pigments to Sexual Reproduction in Plants.

WHEN certain typical plants, such as Cosmos (Cosmos bipinnatus), Salvia (Salvia splendens) and soybeans (Soja max) are exposed to a short photoperiod (7to 8-hour day) and a relatively long one (14to 15-hour day) they exhibit conspicuous differences in rate of growth, time of sexual reproduction and greenness of foliage. The short-day soybean plants, for instance, are lighter in color early in their development, but soon match with the long-day plants and, during the period of reproduction, become intensely green. Since the color of the foliage is due primarily to ehloroplast pigments, a survey has been made during 'the past 3 years of the concentration of chlorophyll (a and i), carotin and xanthophyll in various parts, but mainly leaves, of these plants.3 The results of a large number of determinations show that in the leaves of both shortand long-day group of Cosmos, Salvia and Soja approximately the same concentration of chlorophyll is present, but plants that have changed from vegetative development to the reproductive state have an increased carotin and xanthophyll content, as the following records show: