Abstract
We investigated the effects of end-of-day (EOD)-heating treatment on the growth and flowering of spray-type Chrysanthemum in a low growth-temperature environment. With a controlled 12-hour day length at 16/8°C (light/dark period), we found in the spray-type chrysanthemum ‘Sei-Roza’ that the EOD-heating treatment accelerated flower initiation and early flower bud development. With the objective of reducing energy use in greenhouses in winter, we investigated the effects of short-term heating when the lowest night temperature was lower than 18°C. As a result, when the night temperature was 13°C, the effects of 3-hour 20°C EOD-heating treatment led to about the same timing of flowering as a night temperature of 18°C for the three cultivars we examined (‘Sei-Roza’, ‘Monalisa’, and ‘Wodka Sunny’). We investigated the effects of EOD-heating treatment when the lowest night temperature was 13°C on the characters of flower clusters, which can be a problem for marketing. As a result, deformation of the flower cluster by a low growth-temperature was improved by EOD-heating treatment when we examined four cultivars (‘Sei-Roza’, ‘Sei-Elza’, ‘Monalisa’, and ‘Wodka Sunny’). In this case, heat consumption is reduced by about 15% according to our calculation. From these results, we have successfully shown that EOD-heating treatment is an effective temperature control technique.
