Yesterday was Ada Lovelace day, when bloggers around the world celebrated women in technology. We weren’t aware of it, and frankly, I’m not sure who we might have chosen. Erna Bennett? Fortunately, though, we can direct you instead to Oliver Morton’s fine post on Constance Hartt. Who she?
Hartt was a laboratory researcher at the Hawaiian Sugar Planters Association Experiment Station, and her assiduous work on the biochemistry of sugar cane in the 1930s and 1940s convinced her that, for that plant at least, the primary product of photosynthesis is malate, a four carbon sugar. Later carbon-14 studies showed that she was right — and led to an interesting conundrum. Why did some plants — most plants, indeed, and almost all algae — make a three carbon sugar, phophoglycerate, while sugar cane and, it later became clear, various other grasses made a four-carbon sugar?
Some gene-jockeys seem to think that all that’s needed to double the yield of crop plants is “simply” to give them a C4 photosynthetic pathway. I’m not going to get into that one. But Morton gives a good account of how and why C4 differs from C3, and the part Hartt played in its elucidation.
As follow up I should point to some wise words from Gary on the subtleties of C3 and C4. His point that C4 plants tend to be protein poor is a good one (though in a higher CO2 world that might even out a bit, as the rubisco content in C3 plants will drop whereas in C4 you’d expect it to stay the same, ceteris paribus) and reminds me of Arnold Bloom‘s idea that photorespiration might help with nitrate assimilation. His bigger point is that ceteris paribus is a poor way to see the world, and that to concentrate on any single factor, such as C3 v C4, is to overlook a great deal that you should probably be paying attention to.
sorry about the weird italicisation. No probs; fixed. JC
@Oliver – I think you linked to the wrong post; I think this is the one.
The idea, say, of a multiple harvest from rice crops is interesting. In bits of Texas I know that ranchers grow wheat, allow cattle onto it for a quick bite and then allow the wheat to regrow and set seed, but I have no idea what the overall gains are.