Regulation of photosynthetic activity of crop species subjected to abiotic environmental stresses

This thesis aimed to study regulations of photosynthetic activity of plants under two of the most important abiotic stresses: water stress and salt stress. We mainly focused on the physiological and biochemical mechanisms that regulate growth and productivity under limiting conditions, in order to acquire a better understanding of the complex defense responses of plants to environmental abiotic stresses, which represent the greatest global constraints for agriculture. In order to tackle such broad aim, an integrated approach was necessary. This study was carried out on some specific crops with the peculiar purpose to test cultivars that are tolerant to drought or salinity used under harsh environments. Although abiotic stresses have been largely studied for tomato, pepper and grape species, the specific behavior of many local and typical cultivars and landraces to cope with drought and salinity problems is still new. Hence, the general aim of this work was pursued through three main experimental activities, illustrated in chapters 2-4. Chapter 2 focuses on two typical long-storage tomato landraces grown in greenhouse under extreme (gs< 0.01mol m-2 s-1) water stress conditions ; chapter 3 focuses on two pepper cultivars - grown in a soilless system differently behaving under severe (15.6 dS m-1) long-term salt stress conditions; chapter 4 focuses on a wine grape cultivar, typical in Southern Italy, grown in two soils with contrasting hydrological properties for retaining water.