CALCIUM AMELIORATION OF NACL EFFECTS ON PLANT-GROWTH, CHLOROPHYLL, AND ION CONCENTRATION IN PHASEOLUS-VULGARIS

This study was conducted to determine whether different forms of Ca amendments ameliorated the effects of NaCl stress on growth, chlorophyll content, and ion concentration of snapbeans, Phaseolus vulgaris L. cv Contender. The plants were grown in a greenhouse and irrigated with solutions containing 0, 44, 88, or 132 mM NaCl combined with 0, 5, and 8 mM of either CaSO4 or CaCl2. Without Ca amendments, shoot and root dry weights, chlorophyll concentration, and leaf K+/Na+ ratio decreased more as NaCl increased from 0 and 44 mM than when it increased from 44 to 88 mM. Leaf K+, Na+, Ca2+, and Mg2+ increased and the K+/Na+ ratio decreased with each increase in NaCl concentration. The addition of Ca as either CaCl2 or CaSO4 to all levels of NaCl increased shoot and root dry weights and leaf chlorophyll concentration. The addition of CaSO4 or CaCl2 to different levels of NaCl did not affect leaf K+, Na+, or Mg2+ levels of the leaf. Among the ions, leaf Ca2+ increased significantly as concentration of either CaSO4 or CaCl2 increased. Speciation modeling indicated that a considerable amount of SO4(2-) was complexed as the CaSO4(0) and NaSO4-. Plant survival appeared to be enhanced by SO4(2-) and Ca2+ but not at high NaCl levels.