Methods for the Selection of Low‐Temperature Tolerant Mutants of Chrysanthemum morifolium Ramat. by Using Irradiated Cell Suspension Cultures

In order to improve mutant selection procedures, 5000 plantlets were regenerated in three different harvests (flush A, B and C) from X‐irradiated (15 and 20 Gy) and non‐irradiated cell suspensions of Chrysanthemum morifolium cv. ‘Parliament’. After screening under suboptimal energy condition (12°C greenhouse temperature, winter low‐light), a total of 95 early flowering plants were selected. These plants flowered at least as early as a low‐temperature tolerant (LTT) mutant E 2 , used as a reference. The percentage of early flowering variants was highest among plants obtained from calli, X‐irradiated with 15 Gy and regenerating relatively late (flush B). It appeared that the applied selection method (e.q. harvest) had a large impact on the number of early plants obtained.