Tree Improvement Genetic principles to increase the value of
tree crops
Slide 2
Which Tree Would You Choose?
Slide 3
Why? Why did you choose one tree over the other? What
characteristics did you find most important in your selection? Do
you think you selected the genetically superior tree? How do you
know for sure?
Slide 4
Tree Selection Phenotype: The outward, observable physical
trait of an organism. Incredible differences exist in natural tree
stands These include: growth rate; color; branching habit; disease
resistance; flowering; maturation rate Observed characteristics
such as branching habit is called phenotype of the tree
Slide 5
Trees Phenotype/Genotype Genotype Internally carried, inherited
information that is a blueprint for building and maintaining an
organism. Environment All the living and non-living matter in a
given area that interact with each area and the surroundings The
phenotype of a tree is determine by the following: Its genetic make
up or genotype Effects of the environment where the tree is
growing.
Slide 6
Selection Which of the following tree limbs comes from a
genetically superior tree?
Slide 7
Selection, (continued) Trick Question. Generally speaking you
can not tell genetically superior trees from inferior ones. All or
none of the tree limbs could have come from a genetically superior
tree. Why? The genetically inferior tree may appear phenotypically
appealing because it grew in a unusually favorable environment.
While a genetic superior tree may have been grown in an undesirable
environment, thus shows less than ideal phenotypes. Tree breeders
use the following formula to analyze phenotypes; P = G + E P=
phenotype; G= genotype; E= environment
Slide 8
What you see, might not be what you get! Tree characteristics
vary in which has a greater influence on the phenotype, genetics or
environment For instance branching habit is stronger than height
growth genetically Breeders will have more effect in selecting
trees based on branching habit rather than how tall a tree gets.
This tree is more likely to pass on the drooping branches than it
is height.
