S. Pearson et al., EFFECTS OF TEMPERATURE ON THE FLOWER SIZE OF PANSY (VIOLA X WITTROCKINNA GAMS), Journal of Horticultural Science, 70(2), 1995, pp. 183-190
The effects of temperature on the flower size of pansy were investigat
ed in two experiments under both glasshouse and controlled environment
conditions. Under glasshouse conditions, flower size (mm(2)) decrease
d linearly with increasing temperature between 9 and 31 degrees C (r(2
) = 0.72). A transfer experiment showed that the decrease in flower si
ze was proportional to the magnitude of the increase in temperature an
d to the duration of exposure. Thus, prolonged exposures to higher tem
peratures led to progressively smaller flowers. Temperature prior to v
isible bud stage had little effect on final flower size, but all subse
quent stages were equally sensitive to increased temperatures. Thus, a
period of high temperature had the same affect regardless of the stag
e of floral development. A proportion of the reduction in final flower
size to temperature could be attributed to changes in the duration of
flower development with temperature. A model was developed which show
ed that final flower size could be accurately predicted assuming that
it was a simple function of mean temperature during flower development
and that temperature affected flower size equally throughout developm
ent. Fastest rate of flower development from visible bud was found at
a temperature of 25 degrees C.