INTERACTIVE EFFECTS OF GIBBERELLIC ACID AND SALINITY ON THE GROWTH OF BEANS

Nieman , R. H., and Leon Bernstein . (U. S. Salinity Laboratory, Riverside, Calif.) Interactive effects of gibberellic acid and salinity on the growth of beans. Amer. Jour. Bot. 46(9): 667–670. 1959.—Dwarf red kidney bean plants, grown from the primary leaf stage to maturity on a graded salt series (0, 1.5, 3.0 and 4.5 atm. O.P. NaCl added to a base nutrient solution), showed a progressive and highly significant growth depression with increasing concentration of NaCl. At low levels of salinity (0 and 1.5 atm. O.P.), gibberellic acid applied as a spray to primary leaves, in concentrations of 10 and 100 p.p.m. in distilled water, increased the stem length, fresh and dry wt. of both the top and the root, the yield of green beans, area per leaf, and the total leaf area per plant. At high levels of salinity (3.0 and 4.5 atm. O.P.) growth was so severely suppressed that the expression of all gibberellin effects, except the increase in stem length, was essentially prevented. Gibberellin was, therefore, ineffective in overcoming the salt-induced suppression of growth. An increased rate of water use per unit leaf area was quite consistently observed with the gibberellin-treated plants. This may be simply the result of the increased exposure to light and to air movement of leaves on an elongated stem.