Tetraploid Induction by Colchicines in Rosa banksiae

The diploid rose, Rosa banksiae 'Lutescens', has no thorns, vigorous growth and distinct fragrance. But Rosa banksiae is not cross compatible with the modern tetraploid rose. We attempted to induce tetraploid Rosa banksiae by dipping germinated seeds of Rosa banksiae with root length of 1-2 mm into a colchicine solution before planting into a plug tray. Sprouting and survival were inhibited by colchicine. The frequency of appearance of tetraploids increased at high concentration and long exposure to colchicine, and thirty seven chimeras and tetraploids were observed. The width/length ratio of the leaflet and the guard cell length in tetraploids were larger than in diploids. Both these parameters varied in the chimeras. The average of length of the leaflet serrations in diploids was smaller than that in tetraploids.