Comparative Growth Responses of Northern Red Oak and Chestnut Oak Seedlings to Varying Photoperiods
Northern red oak and chestnut oak seedlings were grown under five photoperiods--8, 12, 16, 20, and 24 hours--for 105 days. Seedlings were harvested at intervals to determine the effect of photoperiod on growth and development. Dry weight, height growth, and leaf surface area were all significantly greater in the longer photoperiods for chestnut oak seedlings. Northern red oak was less responsive to increasing day length. However, root development of northern red oak seedlings under the 8-hour photoperiod was significantly greater than that of seedlings grown under longer photoperiods at all ages. Root-shoot ratios were compared using the allometric relationship log(Y) = b(log X) + log(C), where X is root dry weight, Y is shoot dry weight, and C is a constant. Regression coefficients were not significantly different for northern red oak but were for chestnut oak because of poor performance of seedlings in the 16-hour treatment. Root development of chestnut oak was more rapid than that of northern red oak, possibly an adaptation to the drier sites occupied by chestnut oak. Net assimilation rate of chestnut oak decreased with seedling development. Forest Sci. 24: 554-560.
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