Effect of moisture stress on the growth ofPinus ponderosa Dougl. ex. Laws seedlings in relation to their field performance

Forty wind-pollinated families from eight provenances, four from xeric and four from mesic site types in the Sierra Nevada of California, were examined in the greenhouse for differential response to soil moisture stress. Analysis was made of shoot-root allometric growth coefficients, absolute and relative growth rates and the relationship among these response measures and growth in three field plantations. The results showed significant differences among families for allometric growth (k) coefficients under moderate stress, but no differences among provenances or between site types. Absolute and relative growth rate differences between site types were not significant under any treatment; however provenance differences were observed. Correlation coefficients between plantation performance and greenhouse growth estimates were sometimes significant but significance was plantation and treatment specific. Research performed while author was on sabbatical leave at the Institute of Forest Genetics, USDA-USFS, Placerville, California.