Horticulture - Fruits and Seeds

Genome

The actual genetic makeup of an organism

2 different cultivars =

2 different genotypes

Phenome

Observable characteristics of an organism

Self-Compatible

Plants that accept their own pollen and foreign (same species… different kind)

Advantages of Self-Compatible

Insures reproduction when different genomes are not around, beneficial for colonizing new areas, maintain genetic traits

Disadvantages for Self-Compatible

Reduced genetic diversity and limited adaptability to changing environments

Common Self-Compatible Plants

Tomato, beans, corn, sour cherry, peach, blueberry, grape

Self-Incompatible

Plants that will not accept their own pollen/only accept foreign pollen

• Same species, different genome (cultivar/variety)

Advantages of Self-Incompatible

Insures genetic diversity

Most fruits are

Self-Incompatible

• Ex: Apples, pears, plums, sweet cherry

Ways to overcome self-incompatibility

• “Mr. Rogers Method” - Neighborhood plan to grow certain plants

• Plant a pollinator tree

• Bouquet Method

• Grafting

  • Doesn’t change genome of original plant

  • Helps with space

Fruit

A mature flower ovary containing plant embryos

• Can be fleshy or dried

• Proper fruit development is needed for proper seed formation/development

Seeds are

Alive - go through respiration process (burning sugar)

Seed

A miniature plant surrounded by a protective covering called a seed coat

Seed Germination

Embryo imbibes (absorbs) water and begins to grow:

• Radicle, shoot, leaves

Seed Viability

The ability of a seed to germinate and grow normally

Seed Longevity

How long a seed remains viable

• Different species have different genetics and environment

Factors that affect seed longevity

• Species

• Storage conditions

• 20-30% relative humidity needed

• 40± degrees F darkness

Most vegetable seeds last

2-4 years

Annual seeds typically last

1-3 years

Herbaceous Perennial seeds usually last

2-4 years

Woody Plant seeds usually last

varies from 1-10 years

Nelumbo

Lotus flower

What is required for successful germination?

• Media (soil) / Oxygen

• Moisture

• Warmth

• Light

Vivipary

Latin for live birth

• Seeds germinate inside parent plant

• Ex: Mr. Bryce tomato with roots growing inside

2 types of dormancy

Physical and Physiological

Physical Dormancy

Seed coat is impervious to water

• If water could get in the would germinate

• There is a physical barrier

Physiological Dormancy

Biochemical dormancy

• Even though water can get in, seed won’t germinate

• Seed is filled with certain compounds that prevent germination

How do physiologically dormant seeds have their dormancy requirements met in nature?

Exposure to differing “regimes” (periods) of temperature and moisture

• Warm/dry to cold/moist to warm/moist

How do physically dormant seeds have their dormancy “broken” in nature?

• Natural weathering - freezing, thawing, rain

• Animal digestion

• Scarification

Scarification

Process where the seed coat is compromised to allow imbibition (absorption)

• 3 types

Mechanical Stratification

Using a sharp instrument to compromise a seed coat

• Advantage: Easy

• Disadvantage: Time-consuming, can be dangerous

• Hot water treatment

• Sulfuric Acid (not recommended)

Home Stratification

Process where seeds are exposed to the following environment:

• 60-90+ days in moist media (soil) at temperatures of 45 degrees F or less

• Then place in growing conditions for germination

Why use Polyethylene bags?

• Pervious to gas - oxygen and co2 can move across the membrane

• Impervious to water and water vapor

Double Dormancy

When the seed is both physically and physiologically dormant

• Scarify first to get moisture in, then stratify

Seed propagation equipment and supplies

• Polyethylene Bags

• Labels

• Pen

• Knife

• Paper towels

• Sandpaper

• Talenti - Gelato container (good containers)