OCTOflux part deux

We’re about to start our intensive push to quantify canopy gradients in photosynthetic capacity and light environment across 250 diverse genotypes of wheat at Narrabri. We will use our custom-built high-throughput field gas exchange system, OCTOflux, which can measure Amax in 8 leaves in 15-20 minutes, and our custom-built PARbars — ceptometers that measure average PPFD over a 1 meter horizontal path within a canopy. We’ve just completely overhauled OCTOflux to make some improvements identified during last field season.

Thanks to the International Wheat Yield Partnership (IWYP) and the Grains Research and Development Corporation (GRDC) for supporting this research.

Photos to come. Meanwhile, here’s our logo:



Some new papers

A few new papers have come out recently, on the sites of evaporation, modeling stomatal conductance, the Kok effect, leaf hydraulics and LMA. See below! Most of these papers are posted on ResearchGate or directly from the publisher.


Buckley TN, Scoffoni C, John G, Sack L (2017) The sites of evaporation within leaves. Plant Physiology 173:1763-1782

Buckley TN (2017) Update review: Modeling stomatal conductance. Plant Physiology 174:572-582

Bellasio C, Quirk J, Buckley TN, Beerling DJ (2017) A dynamic hydro-mechanical and biochemical model of stomatal conductance for C4 photosynthesis. Plant Physiology (in press)

Tcherkez G, Gauthier P, Buckley TN, Busch FA, Barbour MM, Bruhn D, Heskel MA, Gong XY, Crous K, Griffin KL, Way DA, Turnbull MH, Adams MA, Atkin OA, Bender M, Farquhar GD, Cornic G (2017) Tracking the origins of the Kok effect, 70 years after its discovery. New Phytologist 214:506-510

Scoffoni C, Albuquerque C, Brodersen CR, Townes SV, John GP, Bartlett MK, Buckley TN, McElrone AJ, Sack L (2017) Outside-xylem pathways, not xylem embolism, drive leaf hydraulic decline with dehydration. Plant Physiology 173:1197-1210

John GP, Scoffoni C, Buckley TN, Villar R, Poorter H, Sack L (2017) The anatomical and compositional basis of leaf mass per area. Ecology Letters 20:412-425

Scoffoni C, Albuquerque C, Brodersen CR, Townes SV, John GP, Cochard H, Buckley TN, McElrone AJ, Sack L (2017) Leaf vein xylem conduit diameter influences susceptibility to embolism and hydraulic decline. New Phytologist 213:1076-1092

New papers

We’ve had some new papers come out in the last few months:


Stomatal optimisation theory: review extension to the whole plant level

Hydraulically mediated, leaf-endogenous responses explain stomatal response to soil drought

Linking stomatal density and index with leaf anatomy and development

Insight article about leaf hydraulic vulnerability

Isotopes and leaf water transport outside the xylem


Coming soon:

Leaf vein xylem conduit diameter influences susceptibility to embolism and hydraulic decline (Scoffoni et al, accepted for New Phytologist)

The sites of evaporation within leaves (in review for Plant Physiology)


Narrabri Field Day

We got to show off our new phenotyping systems, OCTOflux and the PARdots (which is also a good name for a band), at the University of Sydney Plant Breeding Institute (PBI) Narrabri Field Day this week. We also test-fired OCTOflux on wheat for the first time, and will make some final modifications next week. Thanks to Tam Salter for taking photos (click on the pictures for full-size images).


PARdot construction

Progress on manufacturing PARdot handmade PPFD sensors. I’ve soldered 284 photodiodes to their wires and epoxied them to diffusers. Next stage: glue acrylic ring to underside of diffuser and fill with epoxy to waterproof. Field testing at Narrabri next week (weather permitting)!


OCTOflux progress

Tam Salter has made great progress on the OCTOflux high-throughput field physiological phenotyping system for the IWYP project. When complete, the system will be able to measure¬†photosynthesis and transpiration, and thus photosynthetic capacity, on eight leaves simultaneously, using a single-channel IRGA and a bank of solenoid valves to multiplex the sample and reference gas streams. The system will be operated by an Excel program on a laptop (or tablet), using VBA to interface with a DLL that talks to the MCCDAQ data acquisition and relay control boards. The entire system should cost roughly $20k. We’ll be able to complete approximately 32 Amax measurements per hour, enabling a massive step increase in throughput for field physiotyping of diverse germplasm for pre-breeding, or variation in leaf physiology for ecological studies.

We’ll post updates as progress continues, and when the system is dialed in we’ll post complete specifications and instructions for replicating the system.

Gordon conference and Kokference

Just returned from an epic trip to the US and France for a Gordon Conference on Multiscale Plant Vascular Biology and a New Phytologist workshop on the Kok effect (which I have christened the “Kokference”). I presented some cool new work on coupled heat and energy transport in leaves and got to hang out with a lot of really smart people! The Gordon Conference format is really great and conducive to progress — thanks for the organizers for inviting me!

I visited colleagues Matthew Gilbert and Heather Vice at UC Davis on the way back, to pick up instructions and machined parts to build Matthew’s amazing PARdot homemade ceptometers for the IWYP project.