Subsoiling to Stimulate Flowering and Cone Production in a Loblolly Pine Seed Orchard

Abstract

Abstract Subsoiling in a loblolly pine seed orchard was studied in relation to female flowering, cone production, root growth, and soil bulk density. Subsoiling was conducted in late July 1973 in a nine-year-old seed orchard on sandy soil. The average number of female flowers per tree in 1974 and cones per tree in 1975 was considerably greater in the subsoiled plots than in the control plots. There was large tree-to-tree variability. The 1975 flower crop was not affected by the subsoiling treatments. Root excavations made two years after the subsoiling was done indicated vigorous generation and growth of new roots near the ends of cut roots. Soil bulk density was reduced in the upper soil horizons in and adjacent to the subsoiler slits. The stimulating effects on flowering by subsoiling are thought to result principally from the immediate physiological effects of root pruning.