What was done
The authors grew four rice (Oryza sativa L.) cultivars (Pusa Basmati-1 and hybrids P-677, P-834 and P-2503-6-693) in open-top chambers maintained at atmospheric CO2 concentrations of 360 and 600 ppm to study the effects of elevated CO2 on gas exchange (CO2 and H2O) in this important crop.

What was learned
Elevated CO2 increased rates of net photosynthesis in the four cultivars by 25 to 46%.  In addition, it reduced stomatal conductances by 55 to 62%.  Consequently, these two phenomena led to large CO2-induced increases in plant water-use efficiency for all four cultivars.

What it means
As the air's CO2 content rises in the decades ahead, the four rice cultivars studied will likely produce ever increasing yields without proportionate increases in water usage, both of which responses should be welcome news for a world of the future that will likely have many more mouths to feed with very little extra water available to produce the extra needed food.  Hence, more land and water will be able to be reserved for earth's natural ecosystems instead of being appropriated to meet the survival needs of humanity.

Think about these several consequences the next time you see the question "What would Jesus drive?"  That question is based on the premise - or unproven hypothesis - that more CO2 in the atmosphere is bad for the biosphere, when in reality it is not only good, it is essential.