Abstract
In a previous report, new methods of producing small tubers derived from TPS in potato (Solanum tuberosum L.) were described. In the new methods, four small tubers were produced per plant and their fresh weight was 6.9g. Small tubers which weighed more than lg accounted for 65.5% of the total and these tubers were lager than the micro-tubers obtained by the tissue culture method. These small tubers were divided into four class according to their weight and cultivated in plastic film greenhouse. As the size of the small tubers increased, the number and fresh weight of the new tubers per plant also increased. There was a considerable difference in the number and fresh weight of the new tubers between the use of small tubers above lg and that of small tubers below lg. Eighty five percent of the new tubers produced from small tubers above lg weighed more than 20g. These tubers could be distributed to farmers. Planting of 1-3g small tubers of different planting densities did not affect the number of new tubers per plant. However, the fresh weight of new tubers in sparse planting was heavier than that in dense planting. The number of new tubers per 1m2 in dense planting was three times higher than that in sparse planting. And the fresh weight of the new tubers per 1m2 in dense planting was two times that in sparse planting. Thus in sparse planting the number of new tubers above 20g increased. Dormancy of the small tubers could be effectively broken by soaking them at higher concentrations of GAs. However, as the period of GA treatment was long, the number of rotted tubers increased. Furthermore, at higher concentration of GA and during a longer period of treatment, succulent growth was observed in the potato plants. Therefore, the optimum treatment for breaking the dormancy of small tubers was to soak the tubers in GA 50ppm solution for one hour.
