ONTARIO GRAIN FARMER INDUSTRY NEWS 13 for 2011 to 2020 ran through to the end of October; however, as Mussell pointed out, there isn't typically a killing frost by October 31 in southern Ontario. The bottom line, he added, is there's more heat. THE CO2 EFFECT The more intriguing metric cited in Mussell's presentation was the increased concentration of atmospheric carbon dioxide (CO2), its marked increase, and its effect on yields. In plants, there are C3 and C4 photosynthetic pathways with C3s (cereals, legumes and oilseeds) limited in their efficiency. With an elevation in atmospheric CO2, plants bypass that stumbling block with resulting changes in yield. Corn is the exception, and as a C4 plant, it doesn't have a limitation in terms of photosynthesis and photosynthetic efficiency. Oddly enough, corn shows little impact from elevated CO2 concentrations, unlike wheat and barley, which saw a 19 per cent yield response, according to research data. Soybean's yield response was 16 per cent. Mussell conceded that some increases come from an improved understanding of plant physiology and enhanced fertility programs, but the increases due to CO2 concentration are significant. Understanding how CO2 is affecting crop production affects nutrient content, which could affect food security issues for those who rely on wheat and rice. That, said Mussell, leads to a recalibration when considering breeding decisions and the effects on the nutrient value of these crops. continued on page 14
RkJQdWJsaXNoZXIy MTQzODE4