[thedoc (OP)]

Sylvia asked the Naked Scientists:
   Hello Naked Scientists,

I've been enjoying your archived podcasts and also listening to the current ones, which can be a little disorienting; I have a comment on a story that was either aired about a month ago or sometime in 2007 (in which case please disregard). The story was about plants with brown, leaf-mold-imitating bracts.  When the bracts were removed by experimentalists, the plants produced less fruit then the control group.  The conclusion was that the plants were "doing better" when they had their camo coverings on.

We have a lot of trees around our house, mainly oak, hickory, and beech-- all nut-bearers.  Here in Delaware we go through periodic droughts, and during especially bad drought years, the trees produce enormous quantities of nuts.  I would assume that the trees are stressed during those years, rather than "doing better."  I've always just thought that in bad years, the trees work harder to continue the species.  Why would this be different for nut-bearing trees and for fruit-bearing plants?  Were there other objective measures of "doing better" in that study?

Thanks, and keep up the great work, especially Dave the Kitchen Scientist!

Sylvia
Wilmington, Delaware, USA
What do you think?

[chris]

The best measure of plant health is biomass production aka "growth". For growth to happen the plant must absorb CO2 from the air and turn it into glucose through the process of photosynthesis. Glucose is the starting molecule for the synthesis of a host of molecules, including leaves and stems.

Other measures of plant health include measuring the colour of the foliage. There are now devices that use cameras, including even the cameras built into smartphones, to register the pigmentation of leaves and therefore infer the metabolite profile, which is linked to plant fitness.

[smart]

There's many indicators of plant health, including:

• Leaf colour - The colour of leaves should be green
• Irrigation - Is the plant absorbing water?
• Soil composition - Is the soil rich in micronutrients and free of pathogens?
• Leaf shape
• Flowers

See: http://www.landscapeinfoguide.com/articleFiles/201101241922INDICATORSOFPLANTHEALTH.pdf