Ecophysiological responses of Melaleuca species to dual stresses of water logging and salinity

Abstract

The combined effects of salinity and water logging on growth and ecophysiological characteristics of three Melaleuca species were investigated in a glasshouse study. Salinity treatments were imposed from day 28 at 0.3, 0.8, 2 and 5 g NaCl kg^-1 soil. Shoot Na⁺ concentration and Na⁺/K⁺ ratio for M. thyiodes at all salt level and of M. nesophila at 5.0 g NaCl kg^-1 were higher under waterlogged as compared with non-waterlogged conditions. The concentration of Cl^- was double in M. thyiodes and M. nesophila shoots after 2 weeks of water logging at 5 g NaCl kg^-1 soil, but not in M. halmaturorum. Final dry weights of shoots and roots of the three Melaleuca species decreased with increased salinity levels. Shoot dry weight of plants grown at 5.0 g NaCl kg^-1 soil decreased to 30, 50 and 11% of those achieved at 0.3 g NaCl kg^-1 soil for M. halmaturorum, M. thyoides, and M. nesophila, respectively. The results indicated different salinity resistance within Melaleuca species.