Optimization of Seed Potato (Solanum tuberosum L.) Tuber Dormancy and Sprouting Capacity through Integrated Gibberellic Acid and Benzylaminopurine Application

Lack of sprouted seed potato tubers at planting is a major drawbacks for potato production in Kenya as most potato varieties remain dormant longer than three weeks while the window of planting is two weeks. To develop strategies that can enhance earlier sprouting a study was done to determine the effects of application of gibberellic acid (GA) and benzylaminopurine (BA) either singly or in combination sequenced in a time dependent manner on potato tubers genotypes Asante, Dutch Robjn and Kenya Sifa dormancy breaking. The tubers were stored in diffuse light conditions at Kenya Agriculture and Livestock Research Organization (formally Kenya Agricultural Research Institute), National Potato Research Centre Tigoni. The treatments included three potato varieties, Gibberellic acid (GA) applied at 0, 50, 100, 300 ppm and cytokinins (Benzylaminopurine) (BA) applied at 0, 50, 75, 100 ppm. The experiment was laid in a factorial arrangement. Tubers treated with GA alone or with a combination of GA and BA (GA+BA) showed faster dormancy termination and sprout growth than the control and those treated with BA alone. Tubers treated with GA or GA+BA had longer sprouts and number of sprouts per tuber than the control and BA treated tubers in all genotypes. Application of BA compared to GA alone decreased the number of sprouts by 1.46 and 0.89, 1.0 and 0.94, and 0.86 and 1.15 in Asante, Dutch robyjn and Kenya Sifa both in Trial I and II respectively. The highest sprout vigour score of 5.0 and 4.0, 4.33 and 3.67, and 3.67 and 3.33 and the greatest number of sprouts of 5.52 and 4.27, 4.07 and 3.74, and 2.13 and 2.43 was observed when BA was applied just before sprouts emergence at 9 weeks where 15 ppm gibberellic acid and then 15ppm BA after 9 days (GA.9BA) with Asante, Dutch robyjn and Kenya Sifa both in Trial I and II respectively. Both GA and BA may have been involved in initiating dormancy termination and sprout growth probably by synergistically enhancing both cell division and enlargement. Therefore GA or a combination of GA and BA can be adopted for potato dormancy termination and sprout growth. However, BA is more effective when applied toward the end of dormancy breakage.