Ines Hugalde,* Summaira Riaz, Cecilia Aguero, Nina Romero, Felipe Barrios-Masias, Andy Nguyen, Hernan Vila, Andrew McElrone, and Andrew Walker
*Estación Experimental Agropecuaria Mendoza, INTA, Estación Experimental Agropecuaria Mendoza, INTA, San Martín 3853, M. Drummond (5507), Mendoza, Argentina (hugalde.ines@inta.gob.ar)

Rootstocks are a valuable tool for viticulturists, conferring numerous advantages, among which vigor control is important. This research studied F1 progeny from a cross between Ramsey and Riparia Gloire de Montpellier, rootstocks that confer high and low vigor, respectively. We hypothesized that vigor, defined as canopy biomass, correlates with growth rate, leaf area (LA), specific leaf area (SLA), biomass partitioning, and plant and root hydraulic conductance and also that these variables could be associated with genetic markers. We evaluated 138 seedlings from this cross, three replicates each, for 60 days in a greenhouse at UC Davis, California, during summer 2014 and 2015. Each plant was pruned to a single shoot and watered daily. Shoot growth rate, leaf area, and dry biomass were measured in the complete population both years. In 2014, a subset of 50 genotypes was subjected to water deficit (50% of soil water content) after day 45 and evaluated for plant hydraulic conductance, root hydraulic conductance, stomatal conductance, and water potential. In 2015, a subset of 50 genotypes, own-rooted or grafted with Cabernet Sauvignon, was evaluated for photosynthesis and root hydraulic conductance. The 2014 data showed significant QTLs for LA, SLA, and partitioning indices on chromosomes 1, 4, 16, and 5: accounting for 20% of LA and 10 to 14% of SLA, and partitioning indices explained variation. QTLs for LA have also been found on chromosome 4 in Ugni blanc. Hydraulic data from 2014 and mapping data from 2015 are being analyzed.

Funding Support: Estación Experimental Agropecuaria Mendoza, INTA