AN IDEOTYPE OF CHRYSANTHEMUM (C. MORIFOLIUM RAMAT.)

An ideotype is presented of a spray chrysanthemum for summer flowering in all-year-round schedules.
It shows the following characteristics:

1. Strong apical dominance whilst growing vegetatively, and rapid and widespread release of axillary meristems from apical dominance after the removal of the vegetative terminal meristem or after the initiation of a terminal flower bud.

2. A low or no minimum leaf number giving initiation of terminal flower buds immediately short days (S.D.) are begun.
   Subsequent rapid flower bud initiation of axillary meristems.

3. A very high maximum leaf number giving marked delay of bud initiation in long days (L.D.). An equally high leaf number in L.D. whether shoots are released from apical dominance by the removal of a vegetative terminal meristem or by the initiation of a terminal flower bud.

4. A very high leaf initiation rate in L.D.

5. Long internodes and rapid internode extension in S.D.

6. Extremely rapid flower development in S.D. and, ideally, in L.D. too.

7. Moderate peduncle extension in S.D. and L.D.

8. A ‘thermozero’ temperature response, showing little or no delay in flowering at temperatures above and below 15. 5 °C.

9. Easily rooted cuttings which, prior to rooting, can withstand cold storage (0 °C) for ten days without adverse effects.

10. Strong peduncles and strong stems which take up water after a period ‘boxed’.

11. Large, horizontally arranged leaves.

12. Pink blooms.

13. Low competitive ability.

The ideotype is discussed in relation to data from a forty cultivar trial, and broad sense heritability values for several of the ideotype characteristics are given.

I International Symposium on Floriculture Plant Breeding and Genetics

F.A. Langton, K.E. Cockshull

https://doi.org/10.17660/ActaHortic.1976.63.21