System to monitor grape vine water status wins water start-up prize

By Daniel Collins 09/03/2010 1

Fruition Sciences, based in the US and France, has won the top prize in Imagine H2O‘s competition “to help innovators and entrepreneurs turn great ideas into real-world solutions that ensure available clean water and sanitation.” Fruition showed particular business potential by making significant water savings for nine California grape growers.

“Fruition co-founder Sebastien Payen said he saw a real challenge in the wine industry because there were “absolutely no plant-based sensors to optimize water management.”

He combined his expertise in sensor and information technology with co-founder Thibaut Scholasch’s research on vine water status to create the Web application.”

The system seems to work as follows.

Sap flow sensors at the base of the vines monitor how much water is flowing through the plants, and hence how much is transpiring. Weather data and knowledge of the site are used to estimate the evaporative demand at any particular time. This is the rate the soil and plants would lose water by evapotranspiration if they had all the water they could use. These data are sent off for analysis by “proprietary algorithms”, to compute how much irrigation should be applied, and when, in order to optimise fruit composition.

The water saving most probably comes from irrigating only if it would increase transpiration. Above a certain level of soil moisture, called the stress point, transpiration levels out. At this point, more water won’t mean more transpiration, but would mean more evaporation. And if you go even higher, to the soil’s field capacity, you’d start losing water below the roots from gravity drainage. For the plants, evaporation and drainage are a waste of water.

The proprietary algorithms no doubt estimate the actual transpiration rate of the plants and the potential rate imposed by the microclimate, and then assess whether the plant is stressed, how stressed, and whether it should be irrigated.

Sap flow sensors are are a step up from measuring soil moisture status alone, which is also monitored to guide irrigation applications, but is further removed from what is actually going on in the plant and hence typically less informative.

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