Calcium starvation increases salt susceptibility in olive plants but has no effect on susceptibility to water stress

Abstract

SummaryThe responses of leaf water status, growth, and ion concentrations to water or to saline stresses were compared in olive cuttings of different Ca2+ status. Mist-rooted ‘Picual’ olive cuttings were grown in a greenhouse in 2 l plastic pots containing perlite. A nutrient solution with or without 2.5 mM CaCl2 was initially used to irrigate the plants. When the Ca2+-starved plants differed in height from the Ca2+-treated plants, water or saline stress (i.e., no irrigation or 75 mM NaCl, respectively) were applied. The results indicated that Ca2+ increased growth in saline-treated plants, but not in water-stressed plants. After 98 d growth, the stresses were relieved and the plants were irrigated again with or without Ca2+. Growth increased and leaf water status was increased during this recovery period, but no direct effects of Ca2+ were observed in the response of plants to stress-relief. We suggest that the beneficial effect of Ca2+ on tolerance to salt stress in olive plants was related to protection against Na+ toxicity, because there was no response of water-stressed plants to the supply of Ca2+.