Leaf Transpiration Efficiency in Four Corn Cultivars Grown at Elevated Carbon Dioxide

Abstract

ABSTRACTHigh leaf transpiration efficiency (TE) occurs in some cultivars of corn (Zea mays L.) and could be a useful trait to improve yield under water deficits. The CO2 concentration in the atmosphere continues to increase rapidly, and it is not certain that cultivar differences in leaf TE occurring at the current CO2 concentration would still occur at elevated CO2. Two cultivars of sweet corn with high leaf TE and two with low TE were grown for two seasons in plots with free‐air CO2 enrichment systems to determine whether elevated CO2 altered the ranking of the cultivars in leaf TE. Measurements were also made at ambient CO2 2 h and 5 d after termination of the CO2 application. The results indicated that growth at 1.4 times the current CO2 concentration resulted in one cultivar having about 25% higher leaf TE than the other three cultivars, which had similar values of TE. The changed ranking of one cultivar was a result of growth at elevated CO2 and not the elevated measurement concentration. Thus, in one cultivar, the high leaf TE trait was stable across growth CO2 conditions, but in another cultivar, the high TE trait was no longer evident when the plants were grown at elevated CO2. Screening of corn genotypes for high leaf TE at projected future CO2 concentrations may be more efficiently accomplished at those concentrations.