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PlantStudio Kurtz-Fernhout Software
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A common suite of parameters for growth

We separate out these parameters dealing with growth of plant parts because they occur repeatedly in several of the parameter sections (Internodes, Leaves, Male/Female Flowers, Male/Female Inflorescences, Fruit).

Optimal final biomass (as percent of maximum biomass)

This parameter determines how much plant biomass is
allocated to each plant part as the plant grows. You can figure out how much biomass should be placed in each plant part by considering how many plant parts of each type you will have on a mature plant, and what portion of the mature plant biomass will be taken up by vegetative and reproductive parts. Or you can just move each slider around, watch the plant, and check the Parts panel to see how the biomass has been distributed. Make sure you consider the plant's entire life cycle, because a plant that looks good at maturity doesn't always look realistic the rest of its life.

Minimum days for meristem to create

These are speed-limit parameters that simulate physiological limits on the speed of plant growth even when conditions (nutrients, energy, etc) are right for growth. These limits are mainly in terms of the movement of substances through the plant (mass-flow rates) and the rate of chemical reactions that take place during growth. For most plant parts a minimum number of days set at three is a reasonable lower limit.

Minimum fraction of optimal biomass needed to create/open/set fruit

This is what we call the "starting-out" biomass -- enough to get the plant part started so it can start growing on its own. You specify it as a fraction of the optimal final biomass for the plant part. Usually a reasonable minimum fraction to create is about 0.1 or 0.2; to open the flower bud is about 0.5, and to set fruit is about 0.8.

Maximum days for meristem to create

When a meristem is working on creating an internode (and one or two leaves) or an inflorescence, eventually it will have to give up and go on to the next structure even if there is not enough biomass available to make a complete structure. This upper speed limit simulates the plant's preferential allocation of resources to newer plant parts. For most plant parts except fruits, ten or twelve days is usually fine. For fruits the upper limit should be longer, usually 20 days or so.

Minimum days to grow

This is another speed-limit parameter. The internode, leaf, inflorescence, flower or fruit cannot reach full size in any less days than this because it just takes this long to build the plant structure. Usually a minimum of three days is good enough to keep the plant looking correct.

Maximum days to grow

This upper speed limit stops the plant from investing new growth in plant parts that are old enough to have little efficiency (photosynthetic or otherwise). For internodes, leaves and flowers this number might be ten or twelve days. For inflorescences and fruits it should be longer, probably 20-30 days.

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Updated: March 10, 1999. Questions/comments on site to
Copyright © 1998, 1999 Paul D. Fernhout & Cynthia F. Kurtz.