A Comprehensive Evaluation of 12 SDI and RDI Schedules to Irrigate Cabernet Sauvignon in the San Joaquin Valley
Kaylah Vasquez, Guadalupe Partida, Eve
Laroche-Pinel, and Luca Brillante*
*Department of Viticulture and Enology, California State
University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740
(lucabrillante@csufresno.edu)
As drought conditions become more familiar to San Joaquin Valley
grapevine growers, the need for effective water management
solutions has heightened. Understanding the physiological
responses of the plant at various intensities and timings can
still provide great context for more advanced developments.
The purpose of this study was to determine the primary effects of
sustained and regulated deficit irrigation on plant water status,
gas exchange, berry composition, and yield components. We used a
single commercial Cabernet Sauvignon × 1103P vineyard located in
the West San Joaquin Valley. Irrigation treatments were applied
nine times weekly from bunch closure to harvest. Irrigation was
applied using a semi-autonomous irrigation approach and actual
amounts were recorded through flow meters. The plants were
sampled biweekly, starting the week before the first irrigation
event. Irrigation treatments were calculated as fractions of the
grower’s water allocation, which roughly corresponded to 60% crop
evapotranspiration in the middle of the summer. Treatments
included sustained deficit irrigation schedules with 40, 60, 80,
and 100% of the grower allocation and regulated deficit
irrigation strategies with different amounts before and after
veraison. RDI treatments were 100/40, 80/60, 60/100, 100/60,
60/80, 80/40, 40/100, and 40/80, where figures express
percentages of the grower allocation and are formatted as
preveraison allocation/postveraison allocation). In the dry
conditions of our study, limited to one single season of
observation, we found little to no effect of irrigation amounts
on plant physiology, yield, and grape composition. The results of
this study did follow the general trends for grapevines in
semiarid environments, although continued data acquisition is
required to validate the results and observe carryover effects.
We also infer that implementing automated irrigation can be
effective for irrigating remotely and monitoring true amounts; we
do, however, discuss several limitations associated with
precision in large blocks.
Funding Support: American Vineyard Foundation; California State University – Agricultural Research Institute
