Polyploid induction in vitro using colchicine and oryzalin on Hebe 'Oratia Beauty': Production and characterization of the vegetative traits

Nodal segments of Hebe Comm. ex Juss. 'Oratia Beauty' were treated in vitro with colchicine (500 and 1000 mu M) and oryzalin (11.5, 58 and 289 mu M) to induce polyploid plants. Survival rates from treatments were greater than 73%. All explants were rooted, acclimatized and the morphological traits of plants with different ploidy levels were compared. Flow cytometry was used to confirm diploids, mixoploids and polyploids. The highest frequency of tetraploids was 45.7% using oryzalin (289 mu M) and 28.6% using colchicine (1000 mu M). Leaves of diploids and tetraploids were not significantly different for length and width, while some tetraploids showed altered phyllotaxis. Stomatal density was significantly lower and stomatal length was significantly higher in tetraploids when compared to diploids. Principal component analysis (PCA) revealed that stomatal traits accounted for a large proportion of variability. Tetraploids (4x) and controls (2x) were propagated vegetatively and morphology compared. Rooting percentage, number of nodes, height and stem diameter were recorded. There was no difference in the rooting percentage (100%), but tetraploids had thicker stems, were shorter and had fewer nodes than diploids. (C) 2014 Elsevier B.V. All rights reserved.