A system for measuring the CO2 fluxes in roots and top of intact plants

Abstract

An open system for measuring continuously fluxes of CO2 under controlled conditions in whole plants and in their organs, top and roots was developed. Tests carried out with two hybrids of maize (Zea mays (L.)), HS7777 (dent) and HS1227 (flint), showed that this system is suitable for measuring the daily carbon balance. In HS7777, 51% of the gross photosynthesis was incorporated as phytomass in the top, and 16% in the roots; the remaining 33% was consumed by respiration, being 21% in the top and 12% in the roots. In HS1227 53% was incorporated in the top and 10% in the roots phytomass; respiration of the top used 23% and the roots 14%. Specific respiration rate was higher for roots than for top. Photosynthesis, respiration and growth were quantitatively related