Assessment and Selection on the Genetic Resource Test Plantation of Loblolly Pine Introduced from Zimbabwe

Genetic resource of loblolly pine (Pinus taeda) represented by 50families were evaluated for to study the growth performance in seedling and young stage. The result showed that there was significant difference for single tree volume at the age of 5. Fourteen families (include 3 check families) were significantly different from the most inferior one and were considered as superior families. Under the selection rate of 30% for family, the genetic gain for volume was estimated to be 3.1%, with combined selection and 148 selected trees. Height growth at the age of 1 and 3 was relative or extreme significantly correlated with the volume growth at the age of 5. Therefore, the test plantation could be measured only by height, in order to reduce work load, three statistical methods were compared for their using results. Maintenance rate and loss rate of superior families at the age of 5 were compared when selecting the top one third or superseding the bottom one third of all the families. It was suggested that early selection should be implemented by superseding the inferior families.