The role of gibberellin in the Control of Pea growth by Temperature

Abstract

a) Alaska peas were grown in greenhouses maintained at various temperatures, and the effects of periodic treatments with different levels of gibberellic acid on growth and on fresh and dry weight accumulation were measured. Early seedling growth was most rapid at higher temperatures. Gibberellic acid promoted seedling growth at all temperatures. b) Later vegetative growth was most rapid at the lower temperatures. At low temperatures gibberellic acid did not increase the growth rate during this stage, but it did increase growth at high temperatures to a rate approaching that attained at the lower temperatures. c) Gibberellic acid delayed but did not prevent the onset of maturity. d) In complete darkness seedling growth was not influenced by gibberellic acid at any temperature from 10° to 30°. e) Adenine had no significant effect on stem growth or on the onset of maturity at 30° under fluorescent light. f) Gibberellin controls pea seedling growth in response to light but not with respect to temperature. Gibberellin participates in the control of stem growth of older plants, limiting growth in light at high temperatures. It affects but does not control the onset of maturity in these plants.