Initiation and Development of Flower Truss in ‘Momotaro’ Tomato Plants Associated with Night Temperature, and Decrease in the Number of Leaves under the First Truss by Raising Plug Seedlings at a Cool Highland

Initiation and developmental responses of the flower truss in ‘Momotaro’ tomato plants exposed to low night temperature ranging from 7.5°C to 25.0°C for 20 days from germination were investigated in growth chambers, and then the effects were evaluated by raising plug seedlings at a cool highland. Between 12.5°C and 22.5°C, the cooler treatment reduced the number of leaves under the first truss (NL1) from 10.1 to 7.1. The days from germination to anthesis of the first truss (DA1) was shortest at 17.5°C. Night temperatures had little effect on the number of flowers in the first truss. Raising seedlings at a cool highland made the growth of tomato plants compact, i.e., short internode without significant effect on the total number of leaves. When plants raised at the highland were transplanted at a lower elevation, the NL1 decreased by 2.6 leaves, stem length under the first truss was shortened by 15 cm, and DA1 was reduced by 5.4 days as compared to ones sown and raised in the lowland.