Temperature limitations for flowering in strawberry and raspberry.

Sonsteby A.; Heide O. M.

摘要

The effect of night temperature on short day (SD) floral induction in three June-bearing strawberry cultivars of different geographic origin was studied and compared with yield performance in the cool Nordic environment. At the optimum day temperature of 18 degrees C, the SD flowering response of the cultivars 'Florence' and 'Korona' increased significantly with increasing night temperature from 9 to 18 degrees C, while an optimum was reached at 15 degrees C in 'Frida', a cultivar selected under cool-environment conditions in Norway. Also, while saturated flowering response was obtained with three weeks of SD treatment at all temperatures in 'Frida', several plants of 'Florence' and 'Korona' failed to initiate flowers at 9 degrees C night temperature even with five weeks of SD. The effect of extended SD period was particularly pronounced in 'Florence'. The slow SD floral induction response of 'Florence' was associated with a two-week delay of anthesis in subsequent long day (LD) conditions at 21 degrees C. Performance studies of the same cultivars during two years under field conditions also demonstrated that the yield potential of 'Florence' was not realized under the climatic conditions prevailing at these locations. The yields varied significantly among the cultivars, 'Frida' having the highest yields, followed by 'Korona' and 'Florence' far below. It is concluded that, in the Nordic environment, autumn (September) night temperatures are obviously sub-optimal for yield performance of some June-bearing strawberry cultivars, and that this effect is mediated by autumn temperature effects on flower initiation responses. In the biennial-fruiting raspberry cultivar 'Glen Ample', flowering and dormancy induction are controlled by the interaction of low temperature and short photoperiods. As neither process takes place at temperatures above 15 degrees C regardless of the photoperiodic conditions, low temperature is of crucial regulatory importance. Environmental control of annual-fruiting cultivars is also briefly discussed.

Temperature limitations for flowering in strawberry and raspberry.

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