The 2009 ASHS Annual Conference

Dabai rhodo (Rhododendron decorum Franch.) is one of dominant species in mountainous Guizhou, China, especially in the one-hundred miles of natural Rhododendron communities. To introduce this natural treasure to our daily cultivation, two types of cuttings were collected from its wild populations and treated with hormones. Semi-hardwood cuttings with heel produced roots while semi-hardwood cuttings without heel did not survive at all. Hormone type had significantly affected on rooting of dabai rhodo. Dip’N Grow was better and to produce roots at 44 days (74 days for CK) with 53.2% rooting rate (1.12% for CK). Hormodin, straight IBA, NAA, and other yielded 3.9 to 22.6% rooting rates. The quick-dip Dip’N Grow concentration should be 1:10 (1,000 mg∙L^-1 IBA + 500 mg∙L^-1 NAA) and higher or lower concentrations would significantly reduce the rooting ability of dabai rhodo. The quality of root, which measured by the total roots and the longest root length, followed the trend of the rooting rates. Cuttings treated with DipN Grow at 1:10 ratio produced 45 roots per cutting with the longest root of 8.1 cm. Rh. Decorum could be reproduced using semi-hardwood cuttings with heel, quickly dipping into the 1:10 Dip’N Grow for 5-10 seconds, and rooting with perlite and peat moss media. Donglin Zhang is a guest professor at the Central South University of Forestry and Technology.