Tuesday, November 18, 2014
1:10 PM, 2045 Bainer Hall
Topic: "Effect of a Variable Rate Irrigation Strategy on the Variability of Crop Production in Wine Grapes in California"
Speaker: Dr. Luis A. Sanchez
Luis A. Sanchez, Senior Research Viticulturist with E&J Gallo Winery at Modesto, will report on the effect of a variable rate irrigation (VRI) prototype on canopy development and yield for the 2013 and 2014 seasons. The prototype system was implemented in early 2013 in a 10-acre section of a 30-acre drip-irrigated mature Cabernet Sauvignon vineyard. The VRI section contained the full range of lowest to highest yields present in the vineyard (6.1 to 12.4 tons/acre based on the 2012 yield map) and was split into one hundred and forty 15 x 15-meter irrigation zones. Each zone was watered independently by drip irrigation with weekly schedules calculated using an energy balance approach based on the Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC) model. Low yielding zones received up to 17% more irrigation water than the high yielding ones during the 2013 growing season. For both 2012 and 2013, normalized difference vegetation index (NDVI) was calculated and mapped from airborne images captured in mid-August and yield was mapped from yield monitor data collected at harvest.
VRI affected spatial and non-spatial vineyard variability parameters. Non-spatial variability of both yield and NDVI, measured either as percent coefficient of variation or as percent spread, decreased significantly from 2012 to 2013 in the VRI section compared with an adjacent 10-acre section of conventionally irrigated vineyard. Compared to conventional irrigation, VRI also decreased spatial dependency and structure as indicated by the mean correlation distance (MCD) and the Cambardella index. Preliminary results from the 2014 season will also be presented.
Coffee and cookies will be served.