Root growth potential (RGP) of a range of Coastal Douglas-fir Pseudotsuga menziesii [Mirb.] Franco) stocktypes and lift dates was examined as a predictor of site-specific outplanting performance under farm-field conditions of three experimentally controlled irrigation regimes. RGP test results were highly variable. The irrigation regimes resulted in site-specific mortality, growth, and form. RGP was weakly related to mortality and growth, but only for the very driest irrigation regime. For predicting survival or growth of Coastal Douglas-fir under different experimental field moisture regimes, the RGP test is of little use. These results raise questions about the use operational utility of RGP where handling, planting, and climate may further confound the relationship between RGP and plantation survival and performance.
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Updated November 04, 2008