One alternative for adapting viticulture to high temperatures and the scarcity of water is the development of new varieties adapted to such conditions. This work describes six new genotypes, derived from “Monastrell” × “Cabernet Sauvignon” (MC16, MC19, MC72, MC80) and “Monastrell” × “Syrah” (MS104, MS49) crosses, grown under deficit irrigation and rainfed conditions in a semi-arid wine-producing area (Murcia, southeastern Spain). The effect of genotype, year, and irrigation treatment on the phenological, productiveness, morphological, and grape quality data was evaluated. The study material was obtained and selected as part of a breeding program run by the Instituto Murciano de Investigación y Desarollo Agrario y Medioambiental (IMIDA). The results obtained show that under rainfed conditions, the values for productive variables decreased, while those referring to the phenolic content increased. Notable variation in the parameters evaluated was also seen for the different genotypes studied. The behavior of the genotypes MC80 and MS104 under rainfed conditions was noteworthy. In addition to maintaining very adequate yields, phenolic contents, must pH, and total acidity values, MC80 fell into the best ‘phenolic quality group’ and MS104 returned a low º°Baumé value, ideal for the production of low-alcohol-content wines. These genotypes could favor the development of sustainable quality viticulture in dry and hot areas.

Increasing temperatures and drought in Mediterranean wine-growing regions are causing a decoupling between technological and phenolic maturity, as well as a decrease in yield. In this context, the development of new genotypes adapted to these adverse conditions is a key strategy for maintaining the sustainability of viticulture. This study characterises MS104, a novel [Monastrell × Syrah] grapevine genotype, by comparing it with its parental varieties under both controlled irrigation and rainfed conditions in a warm Mediterranean environment. The effect of genotype, year, and irrigation treatment on agronomic, phenological, productivity, and grape quality data was evaluated. MS104 combined an early harvest date, similar to that of Syrah, with an intermediate response to water stress under rainfed conditions, regulated mainly by a greater decrease in stomatal conductance and photosynthetic activity compared to its parents. In addition, under rainfed conditions, it maintained an adequate yield, lower must pH values, higher total acidity and phenolic compound content than its parents, and returned a low °Baumé value, ideal for the production of low-alcohol wines. In conclusion, MS104 is a promising tool for mitigating climate change impacts in warm Mediterranean regions, such as the Region of Murcia in southeastern Spain.