Effect of Gibberellic Acid on the Growth Rate and Physiological Age of Tubers Cultivated from True Potato Seed

Abstract

The time of application of gibberellic acid on potato tuber growth and physiological ageing was studied. Potato plants derived from botanical seed were sprayed at five stages during their growth cycle, and tubers were harvested at 10-day intervals after treatment. It was found that hybrid Chacasina F1 forms tubers until approximately 50 days after transplantation irrespective of the season (spring or autumn). Foliar sprays with gibberellic acid 30–50 days after transplantation suppressed the growth of pre-formed tubers for about 10 days after application and promoted the induction of new tubers, leading to a higher number of tubers per plant in comparison with the untreated control. This temporary effect of gibberellic acid resulted in a reduction in mean tuber weight, but generally without affecting the total weight (yield) of tubers per plant. In addition, gibberellic acid affected the physiological age of the tubers by inducing the breakage of bud dormancy at all stages of tuber growth. Overall, at all harvest times except 90DAT, earlier sprouting and/or a higher number of sprouted buds per tuber were observed for the treatments in which GA was applied within 20 days of harvest.