Can grapevine intra-varietal genetic variability be a tool for climate change adaptation? A case study at a hot and dry environment

Abstract

Climate change projections point to an increase of temperatures and changes in rainfall patterns in the mediterranean region. Grapevine is affected by extreme events, which are likely to change water-availability conditions. It is imperative, when managing future plantations, to select plant material with increased abiotic stress tolerance. It is believed that intra-varietal genetic differences can grant advantages when dealing with these events.

This study aimed to evaluate how different genotypes influence the responses to the environment. Plants of the varieties Tempranillo (TE) (8 clones), Baga (BA) (7 clones), Tinto Cão (TC) (9 clones), Touriga Nacional (TN) (5 clones) and Touriga Franca (TF) (6 clones), planted at a commercial vineyard (Montemor-o-Novo, Portugal), were monitored during the 2023 growing season. From each plant, stomatal conductance (gs) and thermal imagery measurements were performed. The difference between air and canopy temperatures (ΔT), the Crop Water Stress Index (CWSI) and the Jones Index (Ig) were calculated from the thermal and meteorological data. The carbon isotopic signatures (δ13C) were measured in leaves at veraison and in the berry juice at full maturation stage.

The results showed a differentiation between the clones. TE and BA were the varieties that showed the higher variability regarding gs. In BA, the more pronounced differences were found in the thermal indices. It was observed a tight inverse correlation between the gs values and the δ13C in the berry juice, which indicates a higher water use efficiency, a tendency also observed in TC. For all the varieties, gs was better correlated with the δ13C measured in the berry pulp, indicating that WUE can be specifically assessed during the berry formation period. In TE and BA, the clones that presented higher stomatal conductance levels also presented lower ΔT values. The gs of TF and TE presented stronger correlations with the carbon isotopic signatures, while on the other varieties, the gs correlated better with the thermal indices. TN was the variety that showed the lower intra-varietal plasticity. On the other hand, TF showed a relatively high variability of gs. These differences are also corroborated by the thermal indices.

This work shows the importance of considering the intra-varietal genetic variability when managing future plantations, and can be used with the inter-varietal variability, to overcome the negative effects of climate change.