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Garden with Insight v1.0 Help: Plant drawing next day functions: if have just started reproduction, tell all plant parts to switch over

On the day in which the plant changes to the reproductive allocation stage in its life history, it tells the drawing plant. In the drawing plant all the meristems that should switch over to generating reproductive structures switch over. Which meristems switch over to reproductive growth depends on where the flowers and fruits are found on a plant. In some plants the flowers are all at the ends, or apexes, of their branches, so only apical meristems switch over. For example, in a sunflower only the one meristem at the tip of the main stem switches to reproductive mode. In other plants the flowers come from their axillary (side) buds, so only the axillary meristems switch over. For example, in a tomato plant several of its axillary meristems produce little inflorescences with about four or five flowers.

Actually, the method by which the plant places inflorescences is somewhat crude. A plant might have 20 or 30 axillary meristems but only about five inflorescences. In a real plant the creation of inflorescences by these meristems is controlled by complex hormonal gradients. We simply place a number of inflorescences on the plant according to a parameter of how many are expected. We tried doing this using probabilities, but there really is little variation in the placement and number of flowers on most plants. So this part of the plant drawing algorithm is fairly brute force.

One additional factor affects whether meristems change over to reproductive mode when the model plant begins reproductive allocation: the determinate probability. When determinate plants begin reproduction, they go all out and never grow vegetatively again. Indeterminate plants, on the other hand, still grow vegetatively though most of their resources go to reproduction. You may have seen this distinction among tomato varieties: bush varieties tend to be determinate (they grow, then flower, then die), while vine varieties are usually indeterminate (they grow, then flower and grow, then flower and grow some more, and may be kept alive and growing for a long time in a controlled environment). We simulate that difference here using a determinate probability, which is the probability that any one meristem will switch over to reproduction when the model plant enters its reproductive phase. A determinate probability of one means that the plant makes no more vegetative parts. A determinate probability of zero means the plant will never flower. And a determinate probability of 0.5 means that about half the meristems will switch over and half will keep growing vegetatively. For vine tomatoes the value is probably about 0.8.

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