EFFECTS OF WATER DEFICIT ON PROLINE CONTENT AND ACTIVITY OF ANTIOXIDANT ENZYMES AMONG THREE OLIVE (Olea europaea L.) CULTIVARS

The olive tree (Olea europaea L.)، a representative drought – stress – tolerant plant، is one of the most typical and economically important plant species. As olive cultivars may exhibit different level of drought tolerance، the selection of the most drought – tolerant for cultivation in this area is important. For this purpose، the effect of water deprivation on plant water potential (ψw)، relative water content (RWC)، total soluble protein، proline، malonedialdehyde (MDA)، superoxide dismotase (SOD) and preoxidase enzyme activity in three olive cultivars (Olea europaea L. var ‘Dezfoli’، ‘T2’، ‘Koroneiki’) was studied. Olive trees، grown under field condition in Ahwaz were kept without irrigation for 14 days periods. Changes Of these parameters were measured on 1st، 4th،8th، 13th of the period. Plant water status (ψw)، relative water content (RWC) and total soluble protein of three cultivars decreased with increasing level of drought stress. Proline and MDA content increased with increasing level of drought stress. There was not any significant difference among three cultivars except MDA. Dezfoli showed lower value of MDA content. Significant increasing of SOD and POX activity was observed during the progressive increment of drought stress in all three cultivars. Dezfoli showed higher levels of SOD activity. We concluded higher levels of SOD activity and lower level of MDA in Dezfoli during the development of drought stress indicate this cultivar has more tolerance to oxidative stress due to drought stress than the other cultivars.