Two integrated platforms to detect source-sink carbon movements in grapevine

To study the allocation kinetics of carbon in the different sinks competing in grapevines, a plant growth chamber for stable isotope labeling has been set in an environmental control system (light intensity, temperature and relative humidity of the air, pot water content) in order to simulate different climate scenarios. Basing on pulse-chasing isotopic strategy, the isotope acted as a tracer of carbon phloem flows. Furthermore, an open-air plant/soil growth system consisting in twelve independent plant/pot balloons with computing-adjustable air flows allowing continuous gas exchange detection between plants / soil and atmosphere has been set. The two platforms have been coordinated and used before, during and after induction of drought stress. Photosynthetic assimilation, stomatal regulation and respiration have been checked in the various phases to size 13CO2 enrichment flows in the chamber for stable isotope labeling. Maximum assimilation ranged from 9 to 12 μmol m-2 s-1, reduced by stomatal control 3 o 4 times at the end of the drought period. Saturation of net photosynthesis occurred around 1000 μmol m-2 s-1 PPFD: thereafter photoinhibition impairment started in old leaves, whereas young leaves experienced half of maximum assimilation without drastic photoinhibition. An in-vineyard parallel trial of measurements was used to calibrate and reference pot measurements. Financial support: CARBOSTRESS project - Cassa Risparmio Torino Foundation.