A multiplexed gas exchange system for increased throughput of photosynthetic capacity measurements

Existing methods for directly measuring photosynthetic capacity (Amax) have low throughput, which creates a key bottleneck for pre-breeding and ecological research. Currently available commercial leaf gas exchange systems are not designed to maximize throughput, on either a cost or time basis.

We present a novel multiplexed semi-portable gas exchange system, OCTOflux, that can measure Amax with approximately 4-7 times the throughput of commercial devices, despite a lower capital cost. The main time efficiency arises from having eight leaves simultaneously acclimate to saturating CO2 and high light levels; the long acclimation periods for each leaf (13.8 min on average in this study) thus overlap to a large degree, rather than occurring sequentially. The cost efficiency arises partly from custom-building the system and thus avoiding commercial costs like distribution, marketing and profit, and partly from optimizing the system's design for Amax throughput rather than flexibility for other types of measurements.

Throughput for Amax measurements can be increased greatly, on both a cost and time basis, by multiplexing gas streams from several leaf chambers connected to a single gas analyzer. This can help overcome the bottleneck in breeding and ecological research posed by limited phenotyping throughput for Amax.