EFFECTS OF GIBBERELLIC ACID ON GROWTH, TUBER FORMATION AND CARBOHYDRATE DISTRIBUTION IN SOLANUM TUBEROSUM

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Abstract
Summary: Two series of experiments have been described. In the first, plants treated with gibberellic acid (GA), together with untreated controls, were harvested at intervals from the time of planting and the growth of shoots, stolons and tubers measured and the dry weight and sugar and starch values determined. Treatment with GA enhanced both shoot and stolon growth and dry weight, but delayed tuber initiation. The appearance of starch correlated closely with tuber Initiation in both treated and untreated plants, but there was no correlation between sugar level in the stolons and their tuberization. In the second, 14CO2 was fed to single leaves of plants in which tuber initiation had just commenced. In untreated plants, almost all the translocated 14C accumulated in the tubers, in plants pre‐treated with GA a few days earlier, practically no 14C was detected in the stolons or tubers, but accumulated in the shoot, particularly at the apices. There were significant differences in the relative amounts of 14C in the ethanol‐soluble and ethanol‐insoluble fractions in the two treatments. The pattern of translocation shown is held to reflect the activity of the various metabolic sinks, the activity of these sinks being hormonally controlled.