Effect of hormones on the growth of autotrophic seedlings of Cuscuta

The effect of plant hormones during the autotrophic growth phase of Cuscuta seedlings has been studied. Gibberellic acid and abscisic acid do not affect significantly the longitudinal growth of seedlings both in the light and in darkness, but fresh weight is inhibited and seedlings looked thinner with GA treatment compared to the control. Ethylene, cytokinin and high concentration of auxin exhibit very marked growth inhibition which is accompanied by swelling of the stem. The cytokinin response is in more than one way different from ethylene or auxin response; marked increase in greening of seedlings, papillae formation and also the nature of fresh weight changes at very low cytokinin concentration characterize cytokinin response. It is suggested that the autotrophic seedlings of Cuscuta respond to the applied growth hormones in a manner similar to other angiosperms but exhibit some characteristic features of its own like the insensitivity to ABA and formation of papillate structures with cytokinin.