Research on Variation and Selection of Clone Cone Productivity in a Loblolly Pine Seed Orchard

Two hundred and twenty seven clones in Yingde Loblolly Pine Seed Orchard were studied for their cone productions.The result showed that there was very large variation in cone production.The differences between clones,ramets and years were all significant.Cone production was weakly or not correlative with height, DBH and volume growth.However,the correlation between cone productions in different years were strong,and those of every year and the average of three years were the same.The repetition ability of cone production was over 0.6.The observation data of cone production for 3～4 years can be used to determine cone productivity of the clones in future.When the clones with high cone production,which account for 25%～30% of all the studied clones,are re selected to establish an advanced seed orchard,64%～145% or higher of cone production can be made over the average of the selecting population.