Technical Abstract: Six flow-through chambers (8 m3 volume) were built for the measurement of gas exchange (co2 and H20v) from whole vines under deficit irrigation that was meant to impose water stress at different stages of berry growth. Chamber design criteria and materials used were selected to minimize environmental effects of the enclosure, and to accommodate the trellis of a mature, field-grown vine. A framed design allowed the chambers to withstand sustained winds up to 13 m s 1, overcoming one disadvantage of the balloon-type chambers. At canopy height, air temperature was no more than 2.5 °C higher than at the same height in an unchambered canopy. Over 24 h, solar radiation inside the chamber was 90% of ambient. For vines irrigated according to standard industry practice, maximum values of next C02 exchange approached 12 'mol m 2 s 1, whereas in deliberately water-stressed vines the maxima approached only 6.5 'mol m 2s 1. Likewise, the chamber system detected reduced transpiration among water stressed plants, where maximum rates averaged 1 mmol m 2 s 1 as opposed to vines under standard irrigation, at 2.5 mmol m 2 s 1. Apparent light saturation for canopy photosynthesis was approximately 1200 'mol m 2 s 1 PPFD (photosynthetic photon flux density) for vines under standard irrigation, and about 800 'mol m 2 s 1 PPFD for vines under additional water stress.