RESPONSE OF THREE OLIVE CULTIVARS TO WATER DEFICIT CONDITIONS: PHOTOSYNTHESIS, WATER USE EFFICIENCY AND MINERAL NUTRIENT IMBALANCE

The effects of water stress on photosynthetic rate (Pn), intrinsic water use efficiency (WUE), chlorophyll (Chl) and ion content were investigated in three olive cultivars (Olea europea ‘Picual’, ‘FS-17’ and ‘Manaki’) for a four month period. Olive trees were subjected to three irrigation treatments, T₁, T₂ and T₃ that received a water quantity equal to 100, 50 and 25% of crop evapotranspiration, respectively. Water-limited treatments reduced the Chl a and b concentrations in ‘Manaki’ whereas the concentration of Chl a was also reduced in the leaves of ‘FS-17’ exposed to T3 treatment. Water stress treatments were effective in reducing P_n of the leaves of olive cultivars. As a result of the T₂ treatment the WUE of ‘Picual’ and ‘Manaki’ was decreased whereas T₃ treatment reduced the WUE in the olive plants. A water stress treatment- and genotype-depended reduction in P, Mg and B concentration was also observed in olive leaves. Under water stress conditions ‘Manaki’ appears to possess a certain capacity to increase leaf P, Ca, Mg and Zn concentrations.