Effects of growth inhibitors and gibberellin on seedling growth of Arabidopsis thaliana

This experiment was carried out to determine the joint effects of Gibberellin and two growth inhibitors and their possible interaction effects on Arabidopsis thaliana at early vegetative growth stages. Effects of all combinations of four concentrations of Gibberellin and five concentrations of Isoxaben also the same concentrations of Gibberellin and five concentrations of Oryzalin on vegetative growth of Arabidopsis thaliana at early growth stages were studied by two independent experiments.Gibberellin and Isoxaben showed significant effects on vegetative growth but they didn’t show any significant interaction effects. Oryzalin also showed significant effects at 1% level of probability on root length and meristem thickness. General features of interaction effects of Oryzalin and Isoxaben with Gibberellin on vegetative growth of the species were similar. The chemicals levels effects on increasing or decreasing length or thickness of hypocotyl, root and root tip meristems deviated from linearity for both the cases but there were remarkable differences between speed and quantity of their effects. High levels of Gibberellin increased hypocotyls length at most levels of Isoxaben and Oryzalin. Hypocotyl length decreased by increasing Isoxaben and Oryzalin concentration level but the speed of the decrement for different levels of Oryzalin was more than that of different levels of Isoxaben. Increment speed of root tip meristem thickness for both the cases were similar to root and hypocotyls length decrement.