The 2009 ASHS Annual Conference

Maples are an important tree in the nursery industry, and have been a cornerstone in the urban tree population.  Species diversity is a key to successful landscape plantings; however, the stressful conditions of urban environments limit the number of species that can be utilized.  Currently in many urban environments only a handful of species comprise the vast majority of planted trees.  The goal of this is project is to select an Acer truncatum specimen suitable for use as an urban street tree and thus broaden the palate of trees available for urban plantings.  Acer truncatum have excellent potential for use as street trees due to their: cold hardiness (in zone 4b); visual appeal and good fall color; limited maximum height which makes it ideal for under-wire planting; and successful use as a street tree in Beijing and other areas of China.  Acer truncatum are currently available in the trade but with minimal selection, and little data beyond anecdotal evidence have been collected.  Cornell University currently maintains a large genetic resource of Acer truncatum  that were collected internationally from 24 seed and wild sources in 1997.

The ecotypes in this study displayed considerable variability of traits.  Substantial differences have been observed in leaf morphology, fall coloration, and rootability of the various ecotypes.  3-year old potted seedlings were subjected to repeated drought cycles in a greenhouse to look for differential physiological performance under drought stress conditions.  Initial screening was carried out in using chlorophyll fluorescence measurements, with the two ecotypes with the lowest fluorescence values and two with the highest fluorescence values selected for subsequent drought studies to characterize the drought performance range of the germplasm at Cornell.  Results from rootability, morphology and gas exchange investigations will be presented.