for students who want to
May is said to be the best time to sow seeds. Can I sow successfully after May is over?
Yes, you certainly can. The seed of the morning glory germinates when the air temperature becomes higher than 20KC, assuming sufficient water and ventilation. In the Chubu region, such conditions are found from the beginning of May through summer. In Tohoku and Hokkaido, June is good for seed sowing. Seeds can be sown earliest in the southern regions. You have to wait a little longer in the north. Because there is still a danger of frost in the late spring, it's best for you to consider the weather as you decide when it's safe to sow your seeds.
The table shows flowering periods as they relate to the date the seeds were sown. You can refer to it so that you'll know when to expect flowering. Flowers begin to bloom about 60-70 days after a May sowing. According to the table, you can see that the time needed for a flower to bloom shortens if you sow later. Why is that true? The reason is that the morning glory grows better when the days are longer. On the other hand, its flower bud begins to develop when the night gets longer than a certain critical time. We call a plant having such a characteristic a "short-day plant".
Plants that bloom in autumn, such as Common Dahlia (Dahlia hortensis), Chrysanthemum (Chrysanthemum morifolium) and Cosmos (Cosmos bipinnatus) have the same characteristic.
There is also a "long-day plant" in contrast to a short-day plant.
The leaves and stem of a "long-day plant" flourish in a short-day season, and the flower blooms when the day becomes longer than a certain critical time
The plants blooming in spring, such as common hyacinth (Hyacinthus orientalis), snapdragon (Antirrhinum majus) and tulip (Tulipa) are long-day plants.
There is another category of plants--those that bloom with no relationship to the length of the day. We call this a neutral plant.
Neutral plants include, among others, the white clover (Trifolium repens), the Asiatic dayflower (Commelina communis) and the creeping lady's sorrel (Oxalis corniculata).
We can regulate the time of flowering, either earlier or later, by using such a characteristic.
For example, we might cover a morning glory seedling with a box at 4:00 in the afternoon, depriving it of light, and then remove the box at 8:00 a.m. the next day, exposing it to the sun. Plants raised in this way--that is, an 8-hour "day" for 1 week followed by natural conditions--will produce flowers that open 20-30 days earlier than plants raised under completely natural conditions.
Do you understand why the autumn chrysanthemum, a short-day plant, is sold in flower shops year-round? 's because we can regulate the length of a day by -using artificial lighting, and in that way we change the season of flower blooming for the autumn chrysanthemum. We still do not understand how flower buds differentiate--that is, we don't understand the mechanism underlying the bud differentiation.