Fig. 1

Morphological changes in tetraploid black locust cuttings undergoing adventitious root development in a sand bed. a Softwood cuttings before cutting. b White callus appeared 10 days after cutting. c-d Yellow callus appeared and tiny adventitious roots emerged (root primordium) at 15 days after cutting. e Adventitious root formation and elongation at 20 days after cutting. As biological replicates, 10 samples were randomly selected from the groups treated with IBA