Choosing a plant for the proposed bolting experiment

In my previous post I speculated about devising an experiment to test whether the "bolting" of plants, i.e. the tendency of plants to shoot up vertically and set seed early rather than developing leaves and roots as desired for harvesting, can be hindered or prevented by some natural means. The plant that would be best for conducting such an experiment would be one that remained small throughout its life cycle, so that a large number of the plants could be grown in one flat. It would have a short life cycle, preferably less than a month, so that the experiment could be performed quickly. It would have an obvious difference in growth habit between its "unbolted" and "bolted" state, as seen (for example) with brassicaceous crops such as cabbages and turnips. It would have to grow essentially self-contained and compact, not sending out runners or suckers that pop up some distance from the plant. And it have to be a plant that's easy to get hold of.

Shot-weed photo from MulchMaid blog

I discussed the matter with a friend of mine, a professional gardener, and he suggested that "shot-weed" would be a good choice. Shot-weed is one of several common names for Cardamine hirsuta, a brassicaceous plant somewhat related to watercress, a small and highly invasive plant that produces long, thin seed pods after only a few weeks of growth at most. When the pods are fully developed, even a slight touch causes them to pop open, sending their seeds flying in all directions, hence the name "shot-weed". I've seen this for myself when pulling weeds in various gardens. Before setting seed, however, shot-weed forms a compact rosette of small leaves (see photograph above).

The difficulty is that shot-weed is one of those things that's easy to find when you're not looking for it. I've probably pulled up hundreds of these plants without thinking about it, yet when I'd actually like to collect some seeds from it, I can't find any. And it's not like you can buy shot-weed seed at the hardware store.

Of plant seeds easy to purchase off the shelf, I thought that radishes, Raphanus sativus, would be a good choice. They germinate quickly and also set seed quickly but would take up more room to grow than shot-weed. My gardener friend thought it was a logical choice.

Now I need to figure out where I can get room to conduct this experiment, if at all possible, and how much room I'll need.

The prevention of bolting, an introduction

Two years ago I took advantage of a friend's generous donation of planter-box space to try growing a number of vegetables, mostly in the brassicaceous family--turnips, kale, mustard greens, and so forth. The results were poor. As I recall it was a poor summer that year, with many cold days and more rain than usual, exactly the conditions that encourage "bolting".

When a vegetable crop "bolts", it puts all its energy into growing vertically, producing flowers and setting seed. If it's a root crop, as with turnips, the root never grows to any useful size; if it's a leaf crop, as with kale, the leaves are few and small. As I learned two years ago, clipping off the apical buds in a plant that has started to bolt does little good: basically (if you'll forgive a bit of anthropomorphism) the plant has decided because of poor growing conditions--insufficient light, inconstant temperature, &c.--it had better produce seed as quickly as possible before conditions get even worse.

Partly because of the failure of my gardening attempts in 2011 I did not attempt to grow any vegetables the next year. Now that it's 2013 and spring is approaching, however, my interest in planting some greens has returned, only this time I'm interested to know: is there any possibility of preventing, or at least hindering, the tendency of vegetables to bolt in poor growing conditions?

This is a thorny matter I wish to approach in a systematic fashion. The questions to be answered are:

1. What is the physiological mechanism in plants that causes bolting?

2. Have there been any successful attempts in (say) commercial agriculture to hinder bolting?

3. If the mechanism of bolting is known and if there have been successful attempts to control bolting, can one derive any conclusions about mechanisms for preventing bolting? If, for example, bolting should happen to be caused by a particular plant hormone, would it be possible to hinder bolting by interfering either with the hormone's production or its action?

4. If some such mechanism for preventing bolting can be determined, are there any biological or chemical agents within the reach of the ordinary gardener that can exploit this mechanism?

5. Can an experiment be devised to test this?

Ontogeny...

...recapitulates phylogeny.
(Actually it doesn't.)