Farshid Hassani, Abbas Zareian and Enayat Rezvani
Seed potato dormancy has been considered in breeding programs, virus-free seed producing and ware potato production. Seed dormancy is different between potato cultivars. Dormancy in potato mini-tuber buds is one of the limiting factors on planting them after harvesting. This study was undertaken in a factorial based on complete randomized design with arrangement three replications to investigating the effect chemical treatments, cultivars and seed size on seed dormancy breaking of potato in 2011-2012 at Seed and Plant Certification and Registration Institute. The results showed that the chemical materials was significant at (p<0.01) on number of days to sprouting, number of days to dormancy breaking and the total number of sprouting. Number of sprouting per tuber and number of days to sprouting and dormancy breaking between two cultivars were different. Utilization of Gibberellic acid reduced the sprouting time from 25 to 13 days. The lowest number of days to dormancy breaking in average of 28.8 days was obtained in applying GA3 on 20-25 mm mini-tuber. Thio-urea application had the most effect on decreasing the days to emergence in average of 25.1days and also increased number of sprout from 1.41 to 2.03. The result of this project showed that with increasing the mini-tuber size, the days to dormancy breaking decreased and also the number of sprout. Therefore application of GA3 is advisable for decreasing days to sprouting, accelerating sprout length and consequently resulted in breaking mini-tuber dormancy of potato for short time.
