Approaching the Genetic Variation and Selection Effect by Stem Straightness of Loblolly Pine

The investigation on the stem straightness of loblolly pine on five 10 year old proven ances tests and one 6 year old half sib progeny tests plantation of seed orchard revealed that,there were marked difference among provenances in each test with GCV =4.64%～15.25% and H2=0.49～0.83,but the variations among families were not significant.The relationship of straightness with most of the growth traits were not close,namely it was independantly inherited.When stem straightness was used in multi trait selection for building lumber or pulp wood,the straight,high yielding and high wood quality provenances or families could be selected.