1. Genetic principles to increase the value of tree crops
Tree Improvement
Genetic principles to increase the value of tree crops

2. Which Tree Would You Choose?

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?

4. Tree Selection 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
Phenotype:
The outward, observable physical trait of an organism.

5. Trees Phenotype/Genotype
The phenotype of a tree is determine by the following:
It’s genetic make up or genotype
Effects of the environment where the tree is growing.
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

6. Selection
Which of the following tree limbs comes from a genetically superior tree?

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

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.