AN APPRAISAL OF THE USE OF RECIPROCAL TRANSFER EXPERIMENTS - ASSESSING THE STAGES OF PHOTOPERIOD SENSITIVITY IN CHRYSANTHEMUM CV SNOWDON (CHRYSANTHEMUM-MORIFOLIUM RAMAT)

Reciprocal transfer experiments can be used to describe the stages of photoperiod sensitivity in daylength-sensitive plants. However, there are inconsistencies in the literature concerning the techniques used a nd, more importantly, the assumptions made when analysing such data se ts. This paper appraises the use of reciprocal transfer experiments, w ith chrysanthemum as a model (short day) plant. Experiments showed lit tle evidence to suggest that axillary meristems were incapable of resp onding to a floral stimulus when released from apical dominance by pin ching (even though the apex appeared vegetative). Five short days give n after pinching resulted in sufficient induction to initiate an inflo rescence, although seven short days were required to commit a plant to flower with a leaf number similar to plants grown in continuous short days. Floral initiation was then visible at the apex after nine short days, Once the inflorescence had been initiated, long days delayed th e early stages of flower development. The results are discussed with r eference to reciprocal transfer experiments in general, and specifical ly in relation to problems that arise when the length of a 'juvenile' phase is confounded with the number of inductive cycles for flower com mitment.