The relationship between endogenous gibberellins and stem elongation rates in the Pisum sativum L. cultivars Progress no. 9 and Alaska



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Texas Tech University


Dwarf Progress No. 9 and normal Alaska Pisum sativum L. cultivars were grown under conditions of darkness or red light. Red light decreased the stem elongation rate of both cultivars. Gibberellin analysis by gas chromatography and mass spectrometry during the linear phase of stem elongation was the basis for identification of gibberellins A5 and tentative gibberellins A1, A8, A17, A20, A38, and A44. Gibberellin A8 was associated with red light-grown Alaska and dark-grown Progress No. 9 during two early harvests. Gibberellin A17 was only associated with red light-grown Progress No. 9. Gibberellins Varied quantitatively within and between cultivar and treatment groups. Gibberellins were inversely related to stem elongation rate independent of treatment or cultivar. It was concluded that neither decreased stem elongation rate during light growth, nor dwarfing in Progress No. 9 was caused by deficient endogenous gibberellins. Further, it was hypothesized that an endogenous inhibitor may be largely responsible for light-reduced stem elongation rates and dwarfing in progress No.9 through a competitive inhibition mechanism.



Plants -- Effect of gibberellins on, Plants -- Effect of light on, Peas -- Growth