Screening su basi fisiologiche per la resistenza al deficit idrico del terreno in ecotipi di pomodoro da serbo reperiti nel Meridione d'Italia

Long storage tomato is crop typical of mediterranean areas, that is increasingly interesting mainly for its agronomic characteristics, being cultivated under no irrigation. In the framework of a wider research activity addressed towards the exploitation and characterization of different long storage landraces, the plant-water relationships were assessed and a preliminary screening among genotypes based on physiological traits was carried out, to identify those adaptive mechanisms which regulate the physiological activity under strong soil water deficit conditions. The research was conducted in 2011, on 10 landraces of long storage tomato, belonging to the collection at the CNR-ISAFoM, Catania (Italy) and selected on the basis of yield and quality traits. No irrigation was applied except at transplanting. Leaf relative water content (RWC) and proline content and leaf transpiration were measured throughout the growing season. RWC progressively reduced with time whilst proline content increased, as well as leaf transpiration. Close relationships were observed between RWC and proline content in the last measurement only (R2 = 0.96). In particular, with RWC decreasing, proline content increased, revealing that genotypes more sensitive to soil water deficit respond to drought stress accumulating more proline into leaves. Therefore, proline accumulation may be considered as an index of plant water stress. These results are also confirmed by leaf transpiration values measured in late growing season (early July), lower in genotypes with a reduced RWC. These results allow to discriminate genotypes within those examined, that could be used in breeding programs for the genetic improvement of tomato for water stress resistance.