“…with these relative sensitivities, a doubling of atmospheric C02 level will result in an increase of dry matter yields by a factor of 1.45 and 1.53 respectively. Such increases are not unrealistic and have been found under experimental conditions (Goudriaan and de Ruiter, 1983;Gifford and Evans, 1981;Lemon, 1983;Combe, 1981).…”