Research by Wageningen UR Greenhouse Horticulture showed that not all Phalaenopsis cultivars remain vegetative when propagated at a lower night temperature. These results are different from the results found in experiments in the United States.
In the United States two Phalaenopsis cultivars remained fully vegetative at a day temperature of 29°C and a night temperature of 23 or 17°C. This would offer perspectives for energy saving. Wageningen Greenhouse Horticulture therefore investigated the temperature reaction of eight cultivars raised at day/night temperature regimes of 28/28, 29/23 and 29/17°C.
The study revealed large differences in pre-spikes between the eight tested cultivars. Some cultivars remained vegetative for a long time but pre-spikes were already formed at an early stage in a number of other cultivars, After spacing in week 39 and removal of the earlier formed pre-spikes in week 40 all cultivars had produced a higher number of pre-spikes at the end of the propagation period.
After propagation, plants were cooled and finished under identical conditions to investigate the effects on flowering. Despite the smaller number of leaves that had split off and the pre-spikes that had been cut off in case of propagation at a lower night temperature, the final measurements showed no great differences in percentage multiple spikes. When discarding heart spikes and too small branches, the average percentage multiple spikes after raising at a day/night temperature of 29/23°C was 8% lower, and after a day/night temperature of 29/17°C during propagation the percentage multiple spikes was 5% lower than the control propagated at 28/28°C.
Some cultivars showed a slightly lower percentage multiple spikes whereas this was slightly less for other cultivars. After propagation at low night temperatures some cultivars yielded slightly more small spikes and some more heart spikes than the control treatment.