Effects of Temperature and CO2 Enrichment on Carbon Translocation of Plants of the C4 Grass Species Echinochloa crus-galli (L.) Beauv. from Cool and Warm Environments

Abstract

Plants of E. crus-galli from Quebec [Canada] and Mississippi [USA] were grown under 2 thermoperiods (28.degree./22.degree. C, 21.degree./15.degree. C) and 2 atmospheric CO2 concentrations (350 and 675 .mu.l/l) to examine possible differential responses of northern and southern populations of this C4 grass species. Translocation was monitored using radioactive tracing with short-lived 11C. CO2 enrichment induced a decrease in the size of the export pool in plants of both populations. Other parameters did not strongly respond to elevated CO2. Low temperature reduced translocation drastically for plants from Mississippi in normal CO2 concentration, but this reduction was ameliorated at high CO2. Plants from Quebec had a higher 11C activity in leaf phloem and a higher percentage of 11C exported, whereas these northern plants had lower turnover time and smaller pool size than plants from the southern population.