Quantitative and qualitative evaluation of selected wheat varieties released since 1903 to increasing atmospheric carbon dioxide: can yield sensitivity to carbon dioxide be a factor in wheat performance?
Global Change Biology, 10 (10):
1810--1819 (Oct 1, 2004)DOI: 10.1111/j.1365-2486.2004.00840.x
Abstract
The sensitivity of yield and quality parameters to carbon dioxide concentration CO2 was determined for individual lines of hard-red spring wheat released in 1903, 1921, 1965 and 1996. All cultivars were evaluated with respect to growth and vegetative characteristics, grain yield and nutritional quality in response to CO2 increases that corresponded roughly to the CO2 concentrations at the beginning of the 20th century, the current CO2, and the future projected CO2 for the end of the 21st century, respectively. Leaf area ratio (cm2 g−1) declined and net assimilation rate (g m2 day−1) increased in response to increasing CO2 for all cultivars during early vegetative growth. By maturity, vegetative growth of all cultivars significantly increased with the increase in CO2. Seed yield increased significantly as CO2 increased, with yield sensitivity to rising CO2 inversely proportional to the year of cultivar release. Greater CO2 yield sensitivity in older cultivars was associated with whole-plant characteristics such as increased tillering and panicle formation. Grain and flour protein, however, declined significantly with increasing CO2 and with year of release for all cultivars, although absolute values were higher for the older cultivars. Overall, these data indicate that yield response at the whole-plant level to recent and projected increases in CO2 has declined with the release of newer cultivars, as has protein content of grain and flour. However, if agronomic practice can be adapted to maximize individual plant performance, CO2 responsive characteristics of older cultivars could, potentially, be incorporated as factors in future wheat selection.