Investigation of photosynthate-C allocation 27 days after 13C-pulse labeling of Zea mays L. at different growth stages

Abstract

Listen

Translate article

AimsPulse labeling of crops using 13C is often employed to trace photosynthesized carbon (C) within crop-soil systems. However, few studies have compared the C distribution for different labeling periods. The overall aim of this study was to determine the length of the monitoring interval required after 13C-pulse labeling to quantify photosynthate C allocation into plant, soil and rhizosphere respiration pools for the entire growing season of maize (Zea mays L.).MethodsPot grown maize was pulse-labeled with 13CO2 (98 at. %) at the beginning of emergence, elongation, heading and grainfilling growth stages. The routing of 13C into shoot and root biomass, soil CO2 flux and soil organic carbon (SOC) pools was monitored for 27 days after 13C-pulse labeling at the beginning of each growth stage.ResultsThe majority of the 13C was recovered after 27 d in the maize shoots, i.e., 57 %, 53 %, 70 % and 80 %, at the emergence, elongation, heading, and grainfilling stages, respectively. More 13C was recovered in the root biomass at elongation (27 %) compared to the least at the grainfilling stage (3 %). The amount recovered in the soil was the smallest pool of 13C at emergence (2.3 %), elongation (3.8 %), heading and grainfilling (less than 2 %). The amount of 13C recovered in rhizosphere respiration, i.e. 13CO2, was greatest at emergence (26 %), and similar at the elongation, heading and grainfilling stages (~16 %).ConclusionsAt least 24 days is required to effectively monitor the recovery of 13C after pulse labeling with 13CO2 for maize in plant and soil pools. The recovery of 13C differed between growth stages and corresponded to the changing metabolic requirements of the plant, which indicated labeling for the entire growth season would more accurately quantify the C budget in plant-soil system.