1. Crop Science 1 Fall 2004 October 14, 2004
Botany Basics 5
Crop Science 1
Fall 2004
October 14, 2004

2. Fruit Structure Consists of: Seeds Ovary wall
Fertilized, mature ovules
Ovary wall
May be fleshy, as in an apple, or dry and hard, as in an acorn

3. Fruit Structure
In some fruits, the seeds are enclosed within the ovary (e.G., Apples, peaches, oranges, squash, and cucumbers)
In others, seeds are situated on the outside of fruit tissue (e.G., Corn and strawberries)
The only part(s) of the fruit that contain genes from both the male and female flowers are the seed(s)
The rest of the fruit arises from the maternal plant and is genetically identical to it

4. Types of Fruits
Classified as:
Simple
Aggregate
Multiple

5. Simple Fruit Develop from a single ovary
Include fleshy fruits such as cherries and peaches (drupe), pears and apples (pome), and tomatoes (berries)
Include dry fruit
Their wall is either papery or leathery and hard such as peanuts (legume), poppies (capsule), maples (samara), and walnuts (nut)

6. Fruit or Vegetable?
Tomatoes technically are a fruit because they develop from a flower
Squash, cucumbers, and eggplants also develop from a single ovary and are classified botanically as fruit

7. Aggregate Fruit Develop from a single flower with many ovaries
Strawberries, raspberries, and blackberries
Flower is simple with one corolla, one calyx, and one stem, but has many pistils or ovaries
Each ovary is fertilized separately

8. Multiple Fruit
Derived from a tight cluster of separate, independent flowers born on a single structure
Each flower has its own calyx and corolla
Pineapples and figs

9. Seeds
Contain all of the genetic information needed to develop into an entire plant
Made up of three parts:
Embryo
Endosperm
Seed coat
Endosperm

10. Embryo A miniature plant in an arrested state of development
Will begin to grow when conditions are favorable

11. Endosperm Built-in food supply In some species the cotyledons
Can be made up of proteins, carbohydrates, or fats

12. Seed Coat Hard outer covering
Protects the seed from disease and insects
Prevents water from entering the seed and initiating germination before the proper time

13. Germination
Complex process where a seed embryo goes from a dormant state to an active, growing state

14. Germination The seed absorbs water through its seed coat
Must have enough oxygen and a favorable temperature
Most species, such as celery, also require light
Others require darkness

15. Radicle First part of the seedling to emerge from the seed
Develops into the primary root and grows downward in response to gravity
From this primary root, root hairs and lateral roots develop

16. Hypocotyl Between the radicle and the first leaflike structure
Grows upward in response to light

17. Cotyledons Seed leaves Encase the embryo
Usually are shaped differently than the mature leaves
Monocots produce one cotyledon
Dicots produce two

18. Dormancy
Seeds are reproductive structures and important to a species' survival
Plants have evolved many mechanisms to ensure their survival
One such mechanism is seed dormancy
Dormancy comes in two forms:
Seed coat dormancy
Embryo dormancy

19. Seed Coat Dormancy
A hard seed coat does not allow water to penetrate the seed
Scarification is used to break or soften the seed coat
Accomplished in nature by:
Heat of a forest fire
Digestion of the seed by a bird or mammal
Partial breakdown of the seed coat by fungi or insects
Accomplished mechanically by:
Nicking the seed coat with a file
Chemically softening the seed coat with sulfuric acid

20. Embryo Dormancy Common type of dormancy
Seeds must go through a chilling period before germinating
Stratification is used to break dormancy
Seeds are stored in a moist medium at temperatures between 32° and 50°F
The length of time required varies by species

21. Other Factors Affecting Germination
Seed age
Older seed less viable than young seed
If it germinates seedlings less vigorous and grows more slowly
Seedbed preparation
Seed depth
Too shallow may wash away with rain or watering
Too deep won't be able to push through the soil
Seedbed moisture
If over-watered will rot

22. Weeds
Many weed seeds are able to germinate quickly and under less than optimal conditions
One reason why they are so difficult to deal with