ISHS Acta Horticulturae 493: I ISHS Workshop on Water Relations of Grapevines
WATER USE OF THOMPSON SEEDLESS GRAPEVINES MEASURED WITH A WEIGHING LYSIMETER DURING A LATE SEASON DRY DOWN PERIOD |
| Author: | Larry E. Williams |
| Keywords: | Vitis vinifera L., canopy conductance, evapotranspiration |
| Abstract:
The water use of Thompson Seedless grapevines has been measured with a weighing lysimeter at the Kearney Ag Center for the last ten years. This report will detail the water use patterns of the vines during the 1997 growing season. Soil surface area per vine within the lysimeter is 4 m2. The vines were automatically watered via drip irrigation whenever 2 mm of water was used. Total vine leaf area prior to cane cutting on 16 July was approximately 27 m2 vine-1 with water use being 64 l vine-1 day-1. Water use decreased to 46 l vine-1 day-1 after cane cutting, which removed approximately 9.4 m2 leaf area vine-1. Irrigation within the lysimeter was terminated on 22 August, 20 days prior to harvest. Water use of the vines was 42 l vine-1 on 21 August and decreased to 12.9 l vine-1 on 6 September. Maximum hourly water use on 21 August and 6 September occurred from 1400 to 1500 h and 1100 to 1200 h, respectively. Maximum canopy conductance occurred at 1200 h on 21 August and was approximately 1.4 mol m-2 s-1. A maximum canopy conductance of 0.45 mol m-2 s-1 was measured at 0900 h on 6 September and declined continuously throughout the remainder of the day. There was a poor correlation between water use measured with the lysimeter and that measured with a neutron probe (using two access tubes installed within the vine row) during the dry down period. The results indicate that water use decreased as the soil dried out due to both a reduction in canopy conductance and leaf abscission. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
