Abstract
BackgroundExisting 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.ResultsWe 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.ConclusionThroughput 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.
Highlights
Existing methods for directly measuring photosynthetic capacity (Amax) have low throughput, which creates a key bottleneck for pre-breeding and ecological research
Validation of TPU‐limited Amax at high C O2 in relation to A versus ci parameters Because triose phosphate utilization (TPU) can limit Amax at high CO2, we investigated whether such an effect would have an influence on results measured at saturating CO2 in wheat
We achieved an average throughput of 16.7 measurements of Amax per hour—4.4 times greater than the 3.8 measurements per hour possible with a single-chamber commercial system, given the mean time for acclimation of Amax to saturating PPFD (13.8 ± 0.4 min to reach 95% of Amax; mean ± SE, n = 131 leaves; data not shown) and allowing 2 min per measurement to enclose a leaf in the chamber, remove it and measure its area
Summary
Existing methods for directly measuring photosynthetic capacity (Amax) have low throughput, which creates a key bottleneck for pre-breeding and ecological research. Available commercial leaf gas exchange systems are not designed to maximize throughput, on either a cost or time basis. The ability to measure such traits using mass produced, field portable gas exchange systems has made these systems a staple of many laboratories, and their impact on scientific progress cannot be overstated. These systems were designed to maximize portability and flexibility, and as a result, they are not optimized for maximal throughput in phenotyping studies. We describe a semi-portable gas exchange system, OCTOflux (Fig. 1), designed to maximize throughput of Amax measurements in field crops. We describe the system in detail, present sample output data, and discuss modifications to further enhance throughput
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