B‐VITAMIN CHANGES DURING GROWTH OF CUCURBIT AND TOMATO FRUITS

Abstract

IN AN EARLIER paper (Withner, 1949) the changes in concentration of B-vitamins during the growth of cucurbit and tomato leaves were described. This paper continues that study by presenting data on the B-vitamin changes during the growth of the fruits from the same plants. As noted previously, the general purpose of this investigation has been a biochemical approach to the problem of the control of growth in plants. Past studies (Sinnott, 1945) of growth rates of cucurbit fruits have shown that during early development growth occurs at approximately equal exponential rates for both large and small-fruited varieties. The rate falls off markedly several days before the maturity of the fruit. Size difference results from the fact that the large-fruited strains continue exponential growth for a few days longer than the smaller varieties. An explanation of the processes which allow the exponential rate to continue longer in the large fruits, or to cease earlier in the small fruits, is a problem of primary significance. In more general terms, what are the biochemical factors that actually control growth, which enable some cells to go on dividing while others of a similar nature no longer do so, which determine how much building material will enter a growing organ? By determining the part played by the vitamins in the physiological ontogeny of fruits and the possible relationship of the vitamin concentrations to the problem of fruit size a start toward the understanding of these questions has been made. At this laboratory Mrs. Wilson (1947) made the first investigations of changes in vitamin concentrations in the fruits of several lines of cucurbits which differed genetically in fruit size. She analyzed them for riboflavin, niacin, and thiamin. The present study extends her work on two of the cucurbit lines by including ten B-vitamins and bv including tomato varieties as another fruit type for comparison.