Rootstock tolerance to drought, one way to deal with climate change

Abstract

Water is the main factor limiting grape production under Mediterranean conditions. The vine water status also strongly impacts grape quality. In the present work, the rootstocks are considered as a way to cope with water deficit. Water use efficiency and conferred vigor related traits induced by some rootstocks in field conditions were compared to those measured in pots submitted to controlled water deficit. The relationship between water deficit responses and conferred vigor are also discussed along with ecophysiological and genetic architecture data.

Twelve genotypes were selected from a mapping pedigree consisting in 138 F1 individuals derived from the inter-specific cross of V. vinifera Cabernet Sauvignon (CS) × V. riparia Gloire de Montpellier (RGM). They were chosen on the basis of phylloxera resistance and transpiration plasticity to water deficit. Cabernet Sauvignon was the scion grafted on each rootstock of this sub-population. The experiment was carried out three years in field conditions with five years-old vines without controlling water supply. Traits related to conferred vigor (pruning weight, leaf area and yield) were measured. Pre-dawn water potential, stem water potential were assessed during the developmental cycle and δ¹³C in sugar was also analyzed on berry collected at harvest. Soil resistivity measurements were carried out one year and will be compared to the water extraction capacity calculated with the pot experiment The δ¹³C differences observed between berries collected on vines grafted on different rootstocks were not explained by leaf area differences. There was no correlation between vigor conferred related traits and δ¹³C values. The pot experiment data showed that the genetic architecture of water deficit responses induced by the rootstocks partially differed from the genetic architecture for biomass accumulation. These results support the idea that the genetic determinism of these two traits is partially independent. Consequently, selection for water deficit tolerance and conferred vigor might be carried on independently. Different perspectives deriving from these results are presented along two strategies: to improve our knowledge of the rootstocks already used and to develop quantitative genetic approaches for the production of innovative plant material.