Growth responses of sunflower hypocotyl disks inoculated with Escherichia coli and Agrobticterium tumefaciens II. Analyses of increases in weight

Fresh and dry weights of sunflower hypocotyl disks treated withbacteria as in Part I of this report have been tested by analysesof variance. These showed that when seedlings from which diskswere prepared had been subjected to different light treatmentsthere were significant differences among all the main treatmentsand interactions between them were analysed. Such interactionswere among bacterial, disk-light and IAA treatments and amongbacterial, disk-light and seedling- light treatments. Dry weightto fresh weight ratios were shown to vary more with the seedlingand disk-light treatments than with bacterial treatments. Theseinteractions are discussed in relation to the possible mechanismsby which E. coli induces proliferation of hypocotyl tissueswhen grown in the light while these bacteria inhibit growthin the dark. (Received December 5, 1967; )