Effects of Gibberellin on Translocation and on Dry Matter and Water Content in Several Plant Species.

Cucumber seedlings (Cucumis sativus L.) were grown on filter paper moistened with aqueous solutions containing various concentrations of different gibberellins. GA increased movement of dry matter from the cotyledons, mainly to the hypocotyl, at concentrations as low as 10^-6 M, the optimum being at about 10^-3 M in light and 10^-4 M in darkness. Of the four pure gibberellins tested, GA₄, which is the most active in promoting hypocotyl elongation, was no more active than the other gibberellins in increasing translocation from the cotyledons, but directed the internal distribution of dry matter to the hypocotyls rather than to the radicle. GA increased water absorption from concentration of 3× 10^-6 M in the dark, but only from 10^-4 M in the light. Concentrations higher than 6× 10^-3 M suppressed water absorption of both dark- and light-grown seedlings. Effects of GA on variations in dry matter, water content per leaf area and water percentage were studied during night hours with sweet lime (Citrus limettioides Tanaka) and gladiolus plants. GA enhanced the depletion of dry matter from leaves of both species plants. GA enhanced the depletion of dry matter from leaves of both species (as it did in Cucumis). It did not, however, affect the translocation from young gladiolus leaves in the growing stage. Water percentage and water content per leaf area were also increased by GA treatment of sweet lime seedlings. The effect of GA on translocation and internal distribution of sucrose-C¹⁴ applied to one primary leaf of bean seedlings (Phaseolus vulgaris L.) was studied 4, 6, and 20 hrs after the application of the sugar. GA decreased the translocation of applied sugar during the first 6 hrs, but increased it later (after 20 hrs) twofold, as compared with a control. GA always increased the upward translocation of C¹⁴ and decreased the downward movement of the isotope. [ABSTRACT FROM AUTHOR]