Effect of NaCl on the growth of whole plants and their corresponding callus cultures

The effect of NaCl on growth was examined for whole plants and callus cultures of a salt-sensitive glycophyte (Phaseolus vulgaris L.), a salt-tolerant glycophyte (Beta vulgaris L.) and two halophytes (Atriplex undulata D. Dietr., which has salt glands, and Suaeda australis (R. Br.) Moq., a succulent). Whole plants were grown in nutrient solution culture at NaCl concentrations of 0.1-250 mM. Callus cultures were initiated from the same seed stock, and similar saline regimes were imposed. Whole plant responses were characteristic for the various types of plants: P. vulgaris showed a decrease in growth with increasing salinity; B. vulgaris showed a slight increase in growth at the intermediate salt level and a decrease at higher levels; A. undulata and S. australis showed well defined growth optima at 62.5 mM and 125 mM NaCl, respectively. Callus cultures of P. vulgaris and the two halophytes grew very poorly when salinity was increased. Callus of B. vulgaris showed the same tolerance to salt as did the whole plants. Thus salt tolerance of the halophytes depends on the anatomical and physiological complexity of the intact plant while callus from B. vulgaris appears to have a mechanism(s) of salt tolerance which operates at the cellular level.