Contributions of Silvicultural Practices Other Than Genetics to Forest Trees

The genetic improvement from past work with agricultural crops can be classified into three types. One type of improvement is that in which the crop is bred for resistance to some type of disease or insect damage. The ability to or the ability not to raise a given crop may depend upon the success of this type of breeding program. A second type of improvement is through the selection and breeding to increase the proportion of some particular chemical constituent of the plant. Selection and breeding with sugar beet varieties has increased the sugar content from six to more than twenty percent for a 3.3 fold increase. Similar increases have been obtained by selecting strains of rubber trees with high latex yielding capacities. Where the photosynthetic productivity is not altered but rather the relative proportion of some constituent of the plant is increased, selection and breeding has usually resulted in increases in productivity in the range of 300 to 400 percent. The third type of improvement through selection and breeding is in the increase in general productivity of the plant with regard to gross volume production, say in bushels per acre in corn or wheat or tons of hay, or quantity of cellulose fiber per acre.

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Author(s): Thomas O. Perry, Wang Chi-Wu

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1957