Review on the Effect of Gibberellic Acid on Potato (Solanum tuberosum L.)Tuber Dormancy Breaking and Sprouting

Abstract

Gibberellins are growth promoters and to date over hundred gibberellins have been isolated and mainly produced in the leaves but may also be synthesized in the root and fruits, but not all are active in plants. Gibberellic acid is a naturally occurring plant growth regulator which may cause a variety of effects including the stimulation of seed germination by breaking seed dormancy. Gibberellins influence the dormancy of seeds, shoots, and other plant parts.  In potato, a condition often physiological rest prevails from the time of tuber initiation until 6 to 12 weeks after harvest depending on varietal characteristics. The rest period has been markedly curtailed by immersing freshly harvested potato tubers in gibberellins. This effect, coupled with the rapid stimulation of growth of various plants by gibberellins, suggested that pre-harvest foliar sprays of this chemical might shorten the rest period of the immature, developing tubers. Gibberellins also initiate the sprouting process of the tubers on the plant when sprouting is least likely. Both pre and post harvest treatments, have effect on breaking dormancy, early emergence of shoots, increased tuber yield and quality of potato Haulm applications of GA3 at 750 and 1000 ppm reduced dormancy period by 24 days and 27days, respectively. It also hastened early physiological maturity, increased average sprout number and sprout length of tubers, respectively. Similarly, dipping treatment of 40 and 50 ppm reduced dormancy period by 18 days and 20 days, respectively, and had more effect over the control than lower concentrations. Haulm application of 750 or 1000 ppm reduced days to emergence by 11 days while dipping of seed tubers in 40 and 50 ppm reduced days to emergence by 6 and 8 days, respectively, haulm applications of GA3 at a rate of 750 ppm or dipping tubers in 40 ppm GA3 solution were found to be optimum