Dry Weight Partitioning and Its Relationship to Productivity in Loblolly Pine Seedlings From Seven Sources

Abstract

Abstract Dry weights of leaves, stems, and roots in loblolly pine seedlings from seven diverse geographic origins were determined after one year's growth in a green-house under (a) moist and (b) droughty soil conditions. In the moist soil regime, seedlings from each of the four coastal sources produced significantly more dry weight than seedlings from each of the three continental sources. Under moist conditions, coastal trees also allocated more dry weight to leaves and less to root than trees from two of the three continental sources. Seedlings grown in the dry regime were considerably smaller and generally allocated a greater portion of their dry weight to root and less to stem than trees grown in the moist regime. Furthermore, seedlot differences in total dry weight and dry weight distribution among plant organs were much reduced in the dry regime compared to the moist regime. These patterns of dry weight allocation were correlated with differences in seedling productivity in some, but not all respects. Patterns of relative plant organ growth appear to be one of the factors causing provenance differentiation in growth rate. For. Sci. 33(2):255-267.