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Garden with Insight v1.0 Help: floral induction

In most plants flowering is triggered by either photoperiod (the length of daylight), by temperature, or by both. In this simulation, the amount to which temperature affects floral induction is determined by parameters for optimal floral induction temperature. The amount to which photoperiod determines floral induction is as follows.

Short-day plants such as corn require long night lengths to flower. The longest nights fall in the fall and winter, so these plants flower in the fall.
Long-day plants such as lettuce require short night lengths to flower. The shortest nights fall in the summer, so these plants flower in the summer. (But lettuce also has quantitative vernalization so it usually flowers in its second year.)
Day-neutral plants such at tomatoes do not depend on photoperiod to flower, but high or low temperatures can retard flowering.

The choice between short-day, long-day and day-neutral is not clear-cut for many plants, so the simulation uses an S curve of hours of darkness vs. floral induction days to calculate the contribution of each day's dark period to floral induction.

This simulation simulates the triggering of flowering by accumulating photothermal units. The photoperiod units (from the day length S curve) and the thermal units (from a sine curve around the optimal temperature) are multiplied each day to calculate the day's accumulation of photothermal units. This means that on a day in which the optimal temperature and photoperiod for floral induction occur, one photothermal unit is accumulated. When the threshold (a parameter) is reached, flowering is triggered and the plant moves into the floral initiation stage.

How it works:
floral induction

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Updated: May 4, 1998. Questions/comments on site to
Copyright © 1998 Paul D. Fernhout & Cynthia F. Kurtz.