Induction of sieve-tube elements in the ray system ofMorus alba L

Abstract

The effect of exogenous supply of a morphactin — chlorflurenol (IT-3456) CME 74050 p at three concentrations of 100, 500, and 1000 ppm (all applied as dispersions in lanolin paste after scraping the epidermis during December, 1976) was studied on two-year-oldMorus alba plants. Almost three months after the treatment of the regulator, along with the normal sievetube elements of the axial system, these elements were recorded in the ray system as well, arranged either vertically or horizontally. In the latter state, they appear to act as a by-pass between the normally formed sieve elements located on either side of the ray. We have termed them ‘ray-sieve-tube elements’ to distinguish them from the normal elements. Simultaneously, some sieve-tube elements having sieve plates on their lateral walls were also noticed in the axial system. A direct correlation was observed between the multiplicity of induction of both element types and increasing concentration of the regulator.