Friday, July 8, 2011

CSSA's Crop Adaptation to Climate Change Report

Note that this post contains a few interesting excerpts from a new report by the Crop Science Society of America (CSSA is an international scientific society comprised of 6,000+ members with its headquarters in Madison, WI.) The title of the report is "Position Statement on Crop Adaptation to Climate Change" [pdf]

"Climate change has far reaching implications for food security, health and safety, and approaches are required for adapting to new climates. Impacts of climate change are becoming evident and there is no indication that these will reverse in the foreseeable future. Action must be taken now to adapt in a timely manner and prevent unpredictable and undesirable outcomes. New crop varieties, cropping systems, and agricultural management strategies are needed to provide options to farmers to counterweight these changes."


Spotlight on Changes in Seasonal Temperatures
In Canada’s Northern Great Plains, where the growing season has lengthened in recent decades, spring frosts now occur about one day earlier with the passage of every 10 years, whereas the frost free season increases about two days (Cutforth et al., 2007). These shifts coincide with earlier spring warming and runoff as well as decreased winter snowfall (Cayan et al., 2001; Cutforth et al., 2007).

Spotlight on CO2 and C3 and C4 Crops
Crops with C3 photosynthesis (soybean, rice, and wheat) respond more positively to increasing CO2 than C4 crops (maize, sugar cane, and biofuel grasses such as switchgrass and Miscanthus). Crops also respond differently to temperature and water availability, e.g. C3 crops are more susceptible to increases in temperature. Given that environmental factors like CO2 concentration, temperature, and water availability will likely change simultaneously (as well as impact biotic factors), it is therefore difficult to make accurate predictions about crop production under elevated concentrations of CO2.


Impacts of CO2 on Crop Quality and Nutrition
Research shows that increased CO2 can reduce grain protein by 4 to 13% in wheat and 11 to 13% in barley (Jablonski et al., 2002; Ziska et al., 2004), while increasing the carbohydrates in grain (Erbs et al., 2010). Depending on the crop, micronutrients also appear to be somewhat diluted by an increase in carbohydrate in the grain. These effects are difficult to explain, and more difficult to separate from whole plant physiological changes. However, they suggest that increased emphasis on research evaluating crop composition, as well as yield, will be needed in the coming decades.


Advances in Drought-Resistant Varieties
Exciting advances have been made through modest germplasm screening projects that identified desirable old cultivars and landraces (naturally developed, local varieties) and subsequently used them as parent stock for breeding. As a result, drought-tolerant cultivars now exist for several crops including soybean, dry beans, rice, and peanut (Brick et al., 2008; Chen et al., 2007; Branch and Kvien, 1992). This initial success capitalizes on millennia of farmer adaptation of crops to particular climates and points the way ahead in adapting crops to future climate change.

Please go to the report to read much more...