EFFECT OF ENVIRONMENTAL FACTORS UPON THE COLOR OF THE TOMATO AND THE WATERMELON

Abstract

A contribution to the knowledge of the physiological mechanism involved in the production of color in fruits of commercial value is of considerable advantage and usefulness at the present time. A premium is always paid for desirably colored products, both in the canning and in the fruit and market gardening industries. The natural color of ripe fruits may be due to pigments of very diverse nature, produced by the protoplast either in the living plastid, in the cell sap, or deposited in the cell wall. The plant physiologist is particularly interested in the biochemical changes which are responsible for the development of these varied pigments, the conditions under which they are produced, and their ultimate fate in the animal body. At the present time the layman is fast becoming familiar with the fact that certain of these yellow plant pigments are precursors of vitamin A and play, an important role in human nutrition. The of higher plants is produced in special organs of the living cell called chloroplasts. According to Zirkle (63) first mention of these granules'' was made by Comparetti (13) in 1791. The living nature of these bodies, however, was not established until almost a century later when Schimper (51) proved that they arise by division of preexisting structures and gave them the name plastids. The pigments of the green leaf were first extracted and given the name chlorophyll by Pelletier and Caventou (50) in 1818, but it was not until 1864 that the first separation of the complex into green and yellow components was made by Stokes (55). In a paper before the Royal Society he stated: I find the of land plants to be a mixture of four substances, two green and two yellow, all possessing highly distinctive optical properties. The green substances yield solutions exhibiting a strong red fluorescence; the yellow substances do not. It is to this man that science owes the discovery of the still widely used method of partition between two immiscible solvents. He stated definitely, For convenience and rapidity of manipulation, especially in the examination of very minute quantities, there is no method of separation equal to that of partition between solvents which separate after agitation. Unfortunately, this discovery was overlooked by i Published as Paper no. 1462, Journal Series, Minnesota Agricultural Experiment Station.