Application of Near-Infrared Spectroscopy to Commercial Vineyards to Map Wine Grape Quality Prior to Harvest
Due to a change in the availability of previously used commercial vineyards planned for use for this project, we relocated the project to a single 45.3 acre Cabernet Sauvignon vineyard located east of Lodi, CA. The vineyard is owned by Constellation Wines U.S. and managed by Mr. Stanton Lange. The vineyard consists of predominantly clone 337 planted on either 110R (22.5 ac) or 1103P (23.8 ac) rootstocks planted on a 8 x 8 spacing (row x vine) with the rows having an east-west orientation. There were 79 rows of each rootstock with approximately 190 vines per row. The vines are trained to a bilateral cordon with a modified vertical shoot positioning trellis (the south wire is not lifted to provide shade for clusters on the south side of the vine).
Two vineyard sampling patterns were established using a grid pattern. One was equivalent to 234 sites and the second resulted in 437 sites across the vineyard. Since we avoided the outer most 3 rows and 3 vines at each end of a row, the actual area being monitored was approximately 42.2 acres. Hence the sampling density for these two grid patterns were approximately 5 and 10 sites per acre. All sample sites were geo-located using a Trimble GeoXH? handheld GPS system.
On June 28 cluster counts were made on 4 vines (#?s 2,6,10 and 14) within the 13 rows identified as part of the 234 site grid resulting in 52 sample sites across 42 acres (1.24 sites per acre). The total number of clusters per vine ranged from 35 to 80. Additional cluster counts were taken on July 31using 8 sample sites within each of the original 13 rows (2.5 sites per acre) gave a range of 31 to 81 clusters per vine.
Cluster weights collected on July 31 in conjunction with the cluster counts indicated a range from 61 to 223 grams per cluster. There was no distinction between count and non-count clusters and undoubtedly accounts for the wide variation in cluster weight. Additional cluster weights taken on August 24th and September 14th provided estimates of yield for harvest planning. The September 14 estimates suggested yields ranging from around 4 to 11 tons/acre. The average yield, based on weigh tags taken at the winery indicated, was 9.03 tons/acre.
Harvest date was based on Brix, while fruit was segregated at harvest was based on anthocyanin content as determined by the Near Infra-Red Spectrometer (NIRS). Harvest occurred on September 28 and 29, 2006. Based on the agreement with Constellation Wines U.S. three 40 ton lots of wine were made, with the following