Ameliorating effects of Ca(NO3)2 on growth, mineral uptake and photosynthesis of NaCl-stressed guava seedlings (Psidium guajava']java L.)

The effect of varying Ca(NO3)(2) Supply (0, 5, 10 and 15 mM) on growth, mineral uptake, leaf chlorophyll concentration and photosynthesis of NaCl-stressed (30 and 60 MM NaCl) guava seedlings (Psidium guajava L.) was investigated. NaCl caused severe leaf damage (necrotic leaf margins). Dry matter production was lower in the 60 mM treatment than in the 30 mM NaCl variant. Addition of Ca(NO3)(2) stimulated shoot growth more than root growth. Ca(NO3)(2) Supply increased leaf K+ and Ca2+ concentration, whereas the Na+ transport to the leaves was inhibited. There was a strong increase in the K+/Na+ ratio in leaves of Ca(NO3)(2)-treated seedlings. Leaf Cl- content was decreased by supplemental Ca(NO3)(2) but Cl- was increased in shoots and roots. N concentration in all parts of the seedlings increased with enhanced Ca(NO3)(2) supply. Leaf chlorophyll concentration and photosynthesis rate were low in NaCl-treated plants, but both factors were enhanced by 10 mM of Ca(NO3)(2). In general, moderate Ca(NO3)(2) Supply (10 mm) had optimal effects on growth and metabolism of NaCl-stressed guava seedlings. (C) 2002 Elsevier Science B.V. All rights reserved.