((PKG))  CO2  
((Banner:  Rice and Rising CO2))
((Reporter/Camera:  Steve Baragona))
((Adapted by:  Zdenko Novacki))
((Map:  Beltsville, Maryland))
((Courtesy Chyron: FAO))
((Banner: US government researchers say rising levels of atmospheric carbon dioxide (C02) affects crops like rice.))
((LEWIS ZISKA, U.S. DEPARTMENT OF AGRICULTURE)) 
Now, we know that CO2 is plant food.  We think there is a dilution effect as the plants become bigger with more CO2, and there is an imbalance between all the additional carbon in the air and the soil nutrients that are not compensating for all that additional carbon.  So, what happens is that carbon to nutrient variation goes up.  So, we think there’s a dilution effect, but, there’s also some other things that are happening.  Plants become more efficient under high CO2, and so their need for nitrogen, which is an important nutrient, may be less.  But they’re bigger, so they may require more.  So, there’s some change in there as well in terms of physiology and function that may be affecting the nutritional status as well.  In addition, there are also changes in terms of the water flow through the plant, and all the nutrients that go with the water flow.  Basically, as you give the plants more CO2, the pores in the leaves that are called stomates, tend to become smaller.  They shrink in size, and so the water, evaporative loss of water is less, and therefore, the nutritional movement through, from the soil to the plant is less and that may also be impacting overall micronutrient concentration. 

Rice was going to respond, and rice is important for a number of different reasons. But one of the primary reasons is that it is the sole source of calories for almost two billion people in the world, and so whatever happens to rice is going to have a big impact on the global community.  So, looking at how CO2 was going to affect rice, looking at how it was going to impact nutrition, growth, trying to find out which variety of rice is going to respond, what are the implications in terms of culture, what are the implications in terms of food, and so on.  There’re so many really cool questions associated with that and that intersection between climate change, CO2, and rice biology.