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Title: Remote Sensing of Canopy Cover in Horticultural Crops

Author
item Trout, Thomas
item JOHNSON, LEE - NASA/ARC242-4
item Gartung, Jimmie

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2007
Publication Date: 4/1/2008
Citation: Trout, T.J., Johnson, L., Gartung, J.L. 2008. Remote Sensing of Canopy Cover in Horticultural Crops. HortScience. 43(2):333-337.

Interpretive Summary: Irrigation water requirements for horticultural crops are difficult to determine by traditional methods because the crops are grown under a wide range of practices. The size of the crop canopy, or how much of the sunlight hits the canopy, can indicate the water use by a plant relative to a reference plant. We measured canopy cover of 12 different horticultural crops in various growth stages on 35 fields on the west side of the San Joaquin Valley in California with a multi-spectral digital camera. We also estimated canopy cover with simple measurements of crop size and spacing. We also compared a vegetation index calculated from satellite images to the canopy cover. The vegetation index was linearly related with measured canopy cover up to a canopy cover of 80% across the wide range of crops. Dimensionally estimated canopy cover also compared well with the photographic measurements. These simple estimates from remote sensing or dimensional measurements may allow improved estimates of water use of a wide variety of crops.

Technical Abstract: Evapotranspiration crop coefficients for horticultural crops are difficult to determine by traditional methods because the crops are grown under a wide range of practices. Several researchers have related the basal crop coefficient to crop canopy cover or noon shaded area. Canopy cover has also been related to aerial or satellite based normalized difference vegetation index (NDVI). We measured canopy cover of 12 different horticultural crops in various growth stages on 35 fields on the west side of the San Joaquin Valley in California with a hand-held multi-spectral digital camera. We also estimated canopy cover with simple measurements of crop size and spacing and calculated the NDVI for each field from Landsat 5 satellite imagery. The NDVI was linearly related with measured canopy cover up to a canopy cover of 80% across the wide range of crops. Dimensionally estimated canopy cover also compared well with the photographic measurements. Simple estimates from remote sensing or dimensional measurements may allow improved estimates of water use of a wide variety of crops.