Tree ImprovementGenetic principles to increase the value of tree crops

Which Tree Would You Choose?

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?

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

Trees Phenotype/Genotype

Genotype

Internally carried, inherited information that is a “blueprint” for building and maintaining an organism.

EnvironmentAll 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:

It’s genetic make up or genotype

Effects of the environment where the tree is growing.

SelectionWhich of the following tree limbs comes from a genetically superior tree?

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

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.