IMPROVEMENT, PROPAGATION AND USE OF TAXODIUM IN SOUTHEASTERN CHINA

There are three botanical varieties associated with the genus Taxodium: 1) Baldcypress (BC) = Taxodium distichum (L.) Rich.var. distichum , 2) Pondcypress (PC) = T. distichum var. imbricarium (Nutt.) Croom and 3) Montezuma cypress (MC) = T. distichum var. mexicana Gordon. Taxodium hybridization promises to combine the best characteristics of superior parents. In 1988, clones T302 (a BC × MC F1 hybrid), T401 (PC × MC), and T202 (PC × BC) were selected in China primarily for growth rate and tolerance to alkaline and salt-rich coastal floodplains. T302 is recommended in China for soils with pH 8.0∼8.5 and salt concentrations <0.2%. Other attributes of T302 included 159% faster growth than BC, good columnar form, longer foliage retention in fall and early winter, and no knees. T302 has been in the USA since January 2002 and is currently under evaluation in over 30 locations in southern USA. The clone was named `Nanjing Beauty' in 2004 as a cooperative introduction of the SFA Mast Arboretum and Nanjing Botanical Garden. In March 2005, the SFA Mast Arboretum received two new clones from China. T140 and T27 are considered more evergreen than T302 and both demonstrate strong salt tolerance. The clones were selected from a field population of T302 × TM—with strong TM characteristics and improvements in growth rate, salt tolerance, form and vigor. T140 grows faster than T27, which produces a wider profile. The foundation of the most recent selections comes originally from crosses made by Professor Chen and Liu in 1992 at the Nanjing Botanical Garden. Pollen from TM was applied to a female T302 and fifteen selections were made in 1995. The main characteristics for selection were 1) fast growth rate, 2) dark green color during the growing season and a red-orange leaf color in the fall, and 3) evergreen leaves. In 2006 or 2007, the results from T140 and T27 will be reported and registered with the Chinese Forestry Department. It will be at least five years before T140 and T27 enter commerce. In June, 2005 there were <100 each of these two clones. T118, T120 and T149 have already been registered with the Chinese Forestry Department at the provincial level, while T302 has been registered at the national level.