Table 2.

Comparison of the results of our carbon partitioning measurements made using collimated detection to those obtained with our prototype 2D PET system. Both measurement methods were applied on barley seedlings that were 10–12 days old. These seedlings were grown and labeled at a CO₂ concentration of 350 ppm. The errors in the measured quantities are mostly due to systematic uncertainties. In both methods the statistical uncertainties were generally a factor of 10 smaller than the systematic errors.

Measurement method	Labeled leaf fraction	Shoot fraction	Root fraction
Collimated detectors	0.35±0.02	0.45±0.04	0.20±0.03
Prototype 2D PET	0.34±0.10	0.52±0.08	0.14±0.03