Ever since Malthus (that's him on the right) even that part of the human race fortunate enough not to have to worry about where its next meal is coming from has realised that figures for global food supply and population don’t add up.

The post-WW2 generation – that is, people like me - was perhaps the first to be able to sit at home with a TV dinner and watch people from another continent starving on the screen in the corner of the room.

Biafra and the like made a deep impression and there was a bulge of recruitment, not just of biologists but also of engineers, physicists and chemists, into the academic and extension services underpinning agriculture.

One outcome was the Green Revolution.  Much derided now, but it really was a proud achievement for a generation more commonly remembered for a different and more decadent kind of flower power.

It hasn’t always been easy to sustain the argument that research on crops is valuable, but until Malthus is finally buried under the green pastures of some kind of new Eden, I believe we have a duty to do it.

A more potent argument against crop research of the kind done by physiologists like me is that it hasn’t led anywhere.  Very influential people convinced themselves of this (some still think it) with the consequence that large numbers of my contemporaries were hosed away in the eighties and nineties.

(Not me, I’m relieved to say, but then I’ve had the great fortune always to have worked for enlightened people and organisations.  I put this down to the temperament and long-term outlook of the plant breeders I’ve hung around with).

Naturally I think the “crop physiology is a waste of time” view was wrong back then and it is certainly dangerous now.  After all, if you want plants to mop up CO₂ it’s a good idea to have people around who know how to measure photosynthesis properly.  There aren’t too many of them any more.

Where I think there is some substance in the sceptical view of crop physiology is in the relatively meagre record of achievement when it comes to increasing the rates of critical biological activities like assimilation.  Nevertheless, the time is fast approaching when this issue will have to be revisited.

My original take on it was that evolution seems to work on biological designs that are drawn on rubber sheets which are then stretched this way and that to make new architectures (it's all in D'Arcy Thompson).

In particular, it’s how long a particular developmental or physiological action lasts rather than some instantaneous rate factor that translates into new biological potential.

If you want to improve your crop (the argument goes), get its solar panels (foliage) out into the light as fast as possible and keep them there as long as you can.  The momentary intrinsic rate of photoassimilation is a lesser consideration.

Hence my long-term interest in growth (making leaves) on the one hand and senescence (losing leaves) on the other.

I think there’s plenty of evidence that large increases in crop yield have been achieved by this strategy and crop agronomists, physiologists, geneticists and breeders who make this happen deserve recognition.

But you only need to visit the IRRI website and watch the figures for world population and productive land area heading in opposite directions to see that we're going to have to do much more if we're going to

Looming over the the issue of agriculture and food is the question of - a resource it's easy to take for granted in cool wet Wales but which, as the link shows, is of increasing global concern.

I’ve written on various aspects of these matters, so if you want to read more, start here:

H Thomas (1992) Canopy survival. In: Crop Photosynthesis: Spatial and Temporal Determinants (ed N Baker, H Thomas) pp 11-41. Amsterdam: Elsevier
H Thomas, C M Smart (1993) Crops that stay green. Annals of Applied Biology 123: 193-219
H Thomas, C J Howarth (2000) Five ways to stay green. Journal of Experimental Botany 51: 329-337