Almost all staple food crops - grains - are annuals. Every year they germinate from seed and briefly but gloriously grow till they set seed and die. The evolutionary strategy of such plants is to put all of their energy into seed and then launch their genome into the future rather than trying to tough it out as individuals. It is the energy dense seed that we eat, so such annuals are more useful to humans than perennials that squander - from our perspective - energy on leaves, stalks, roots and energy stores hidden below ground and unavailable to us as food.

But it's expensive and destructive to gather seed, save it, and then plant it again the next year. It takes energy to do it and wrecks soil structure. It allows weeds to invade fields during fallow times, exposes soil to wind and water erosion, and emits GHGs into the atmosphere. Annual plants avoid all this effort by producing so much seed than only a tiny percentage needs to germinate the next year to assure continuity. But since we want to eat most of the seed we have to be careful to get high gemination rates for the few that we save for species continuity.

If only we could breed plants that produce lots of seed like annuals do, but didn't need to be planted each year. It's an old dream and there are teams in various places trying to work this alchemy and transmute annuals into perennials, or teach perennials to set more seed. We are learning some things.

VIB researchers, such as Siegbert Melzer in Tom Beeckman's group, have studied two such flower-inducing genes. They have deactivated them in thale cress (Arabidopsis thaliana), a typical annual. The VIB researchers found that mutant plants can no longer induce flowering, but they can continue to grow vegetatively or come into flower much later. Melzer had found that modified crops did not use up their store of non-specialised cells, enabling perennial growth. They can therefore continue to grow for a very long time.

As with real perennials these plants show secondary growth with wood formation creating shrub-like Arabidopsis plants.

This doesn't sound so useful. Food crops must flower and set seed or there will be nothing to eat. We can't live on leaves and stems, we need seed. There are some leaf crops that we eat, but they are low energy foods only of use as supplements, not staple foods.

It is useful for herbivores. One of the key objectives of managed grazing systems is to prevent flowering and seed set since many grasses and forbs die after doing so. The methods used to achieve this objective is to clip the sward - keep the plants short. This keeps them young and vegetative since they have to build up leaf mass and root energy reserves before they mature and switch into producing taller woody stalks, flowers and seed.

If there were highly productive annual grasses that didn't set seed and die that would be a great boon to graziers. Now if they could only figure out how to make grasses that produced like C3s in winter and C4s in summer . . .