Effects of chemical treatments on dormancy breaking and some sprouting characteristics of two potato cultivars in different tuber sizes

Seed potato dormancy has been considered in breedin g programs, virus-free seed producing and ware pota to production. Seed dormancy is different between pota to 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 replicatio ns to investigating the effect chemical treatments, cultivars and seed size on seed dormancy breaking of potato in 20 11-2012 at Seed and Plant Certification and Registr ation Institute. The results showed that the chemical mat erials was significant at (p<0.01) on number of day s to sprouting, number of days to dormancy breaking and the total n umber of sprouting. Number of sprouting per tuber a number of days to sprouting and dormancy breaking btwo 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 effe ct on decreasing the days to emergence in average of 25.1 days and also increased number of sprout from 1.41 to 2.03. The result of this project showed that with increas ing the mini-tuber size, the days to dormancy break ing decreased and also the number of sprout. Therefore applicatio n of GA3 is advisable for decreasing days to sprout ing, accelerating sprout length and consequently resulte d in breaking mini-tuber dormancy of potato for sho rt time.