Effects of low temperature before or after acclimatization on growth and flowering of viroid-free chrysanthemum plants by leaf-primordia free shoot apical meristem culture and the variation test

On raising of viroid-free seedlings of chrysanthemum var. 'Jinba' and 'Iwanohakusen' by the new meristem culture method which leaf-primordia free shoot apical is transplanted and cultured on in-vitro cabbage root tips, effects of low temperature before or after acclimatization on growth and flowering of raised plants were examined, and turning the effective treatment to good account, variations of their plants were tested. 1 If plants raised by the new culture method did not met with low temperature, the flowering was more delayed and the stem length was more shortened than by custom method. When the plants met with low temperature (4 deg C) for four weeks after acclimatization, the flowering and the growth of stem were hastened, but it was less effective than natural low temperature in winter, in case the plants met with natural low temperature in winter, the flowering and the growth were as same as the plants propagated by custom method. 2 In 'Jinba', fifteen plants raised by the new culture method varied in flowering period, plant height, node-number, the fresh weight of cut-flower, flower size and floret number, but it was confirmed that the variation did not arisen, because there were no significance to the plants propagated by custom method. 3 In 'Iwanohakusen', some variations were confirmed on eight out of twelve plants raised by the new culture method. Especially, marked variations such as dwarfing or disappearance of tubular florets were occurred in two plants. Variations such as flowering period etc., which are of little importance, were confirmed in the others. From these results, on the raising method of viroid-free chrysanthemum seedlings by leaf primordia free shoot apical meristem culture, it is concluded that superior seedlings are able to be raised by variation test of flowering and growth of redifferented plants met with sufficient low temperature after acclimatization.