Comparative study on gas exchange, water relations and leaf anatomy of two olive cultivars grown under well-irrigated and drought conditions

The effect of water stress on gas exchange, water relations and leaf anatomical characteristics have been studied in two olive cultivars (Olea europea, L. cv. 'Koloneiki' and cv. 'Mastoidis'). Photosynthetic rate as well as stomatal conductance were decreased in stressed plants. Osmotic potential (pi) declined rapidly in stressed plants indicating their ability for osmoregulation. Bulk modulus of elasticity (epsilon) was significantly higher in stressed compared to well irrigated plants. The volume fraction of intercellular spaces of the upper palisade parenchyma, the spongy parenchyma as well as the lower palisade parenchyma were significantly lower in stressed compared to well irrigated plants. On the other hand, the density of mesophyll cells in the upper palisade parenchyma, spongy parenchyma and lower palisade parenchyma increased significantly in stressed plants.