The Selection on Superior Families of 14-year-old Loblolly Pine

The 25 families of loblolly pine introduced from the first-generation seed orchard of the Unites State were tested,the control were masson pine and slash pine.The results of test showed that: the loblolly pine was likely to be infected during early growth period by brown spot of pine needle,and had lower preservation rate,but the growth of 14-year-old loblolly pine was superior to slash pine,and was inferior to masson pine;Each family had evident characteristic differences in tree height,DBH and volume;4 superior families were selected according to the characteristics,14-year-old loblolly pine had average tree height 12.6m,average DBH 20.4cm and average individual volume 0.1981m3,9.2%,25.9% and 71.1% higher compared with slash pine,and their genetic gains were 8.9%,24.7% and 67.9%,respectively.