2017 Volume 16 Issue 2 Pages 155-161
The effects of daily air temperature control in greenhouses on forced cultivar cucumber fruit growth and yield were investigated. Two methods of control were compared in two greenhouses. One has been applied practically in Saga Prefecture, Japan: the air temperature in the morning is maintained higher than that in the afternoon. The other has been applied in advanced countries for greenhouse horticulture: the air temperature is maintained higher in the afternoon than in the morning (PMHT) and decreased quickly (quick drop: QD) in the early evening. The latter method shortened the growing period from anthesis to harvest and promoted fruit growth. On the other hand, the growth of vegetative parts was restricted, and the number of harvested fruits decreased, because of the priority given to fruit growth. Thus, there was no difference in the total yield between the two methods. The temperature differences between leaves and fruits in the early evening were observed under PMHT·QD and the conventional method. The temperature differences were greater in PMHT·QD. These suggested that a higher temperature of fruit than leaves after sunset by PMHT·QD is one of the reasons for the promotion of fruit growth rather than the growth of vegetative parts.
