Grapevine rootstock field evaluation under drought and saline condition in California

Abstract

Climate change impacts grape production worldwide and in California drought and salinity became increasingly challenging for grape growers to maintain sustainable production and fruit quality. Four rootstocks, Freedom, 1103 Paulsen, 140 Ruggeri, and RS 3, were field tested under the drought and saline conditions in the San Joaquin Valley of California. Two scions, Barbera and Colombard, were grafted on those four rootstocks along with their own rooted vines in 2020. Soil and irrigation water were sampled annually to confirm the salinity level, and irrigation B was found consistently at 1.7 ppm which is considered toxic for grapevines. A two-way split block experimental design was conducted in 2024: two irrigation regimes and five rootstocks were repeated four times. 50% ETc and 80% ETc through the growing seasons were applied as the irrigation regimes. Petioles were collected at bloom and veraison to measure the plant nutrients. Mid-day leaf water potential (ψ) and fruit-zone photosynthetic active radiation (PAR) were collected biweekly after fruit set until harvest. Rootstock had a significant effect on grapevine nutrient uptake, berry pH, TA and lowered water stress compared to own-rooted vines when the water deficit was high. Higher water deficit resulted in lower leaf ψ, higher PAR, lower nutrient uptake, smaller berry size, and higher berry anthocyanins content for Barbera. No yield difference was observed from irrigation regimes or rootstocks. Interestingly, a significant difference of petiole nutrient contents between two scions on the same rootstock and irrigation regimes was observed. Data collection will resume in 2025.