Tomato landraces as a source to minimize yield losses and improve fruit quality under water deficit conditions

The predicted climate change conditions are forcing crop improvement researchers to find drought tolerant genotypes. The aim of this experiment was to screen a large tomato (Solanum lycopersicum L.) collection cultivated under well-watered and water deficit conditions, in order to identify those genotypes with the best performance under water shortage. Thus, 165 tomato genotypes including different cultivars (landraces and modern genotypes) and fruit types (processing, big size, long shelf-life and cherry) were grown in open field under two different cultivation regimes: well-watered (WW, covering 100% crop evapotranspiration demands) and water deficit (WD, irrigation stopped one month after field transplantation). Several leaf-level traits, yield and fruit quality were measured. Large variability was found under WW, with 20-fold variations in yield among genotypes. No differences in yield or fruit quality traits were found between modern genotypes and landraces, while differences in these parameters were observed based on the fruit type. Water deficit affected the observed variability, with a general decrease of yield and increases of fruit quality. Cluster analysis based on fruit traits placed several landraces in the same cluster that the most productive modern genotypes, irrespective of the water treatment. Variable responses to WD were observed, depending on the fruit or cultivar type. Carbon isotope composition was positively correlated with leaf nitrogen content, and determined the yield limit under both treatments. The results of this study highlight the potential of landraces for minimizing yield reduction under WD and increasing fruit quality, having similar or even better performance as compared to modern improved genotypes.