Level 1 Horticulture Science AS 90923 Plant Propagation

Plant Propagation The following PowerPoint notes are to support students towards the assessment for: AS 90923 Demonstrate knowledge of basic plant propagation techniques Level 1 4 credits Internal Assessment Achievement Achievement with Merit Achievement with Excellence Demonstrate knowledge of basic plant propagation techniques. Demonstrate in-depth knowledge of basic plant propagation techniques. Demonstrate comprehensive knowledge of basic plant propagation techniques.

Contents The difference between asexual and sexual Types of sexual propagation Types of asexual propagation Seed Sowing Cuttings Division Ground Layering

The difference between asexual and sexual Definitions Asexual Involves only one parent to make a new individual that is a clone of the parent (genetically identical). In plants there are heaps of ways of doing this. Sexual Involves 2 (or 1) parent plants mixing their genes to produce offspring. In plants the parents have ‘sex’ using flowers and the offspring are seeds

Examples of Propagation Asexual Sexual Cuttings Hardwood /Semi-Hardwood/ Soft-wood Grafting Whip and tounge / cleft / budding etc Division Tubers/ runners/ rhizomes/ crown/ stolons/ bulbs/ corms Layering Ground/ air Propagation using Seed Note: Always involves flowers except in gymnosperms (pine trees) ferns and mosses Sexual propagation always results in a seed

Seed sowing To understand seed sowing technique we will be looking at: Seed structure Germination Respiration Seed requirements Seed Dormancy Seed Sowing Menu

Seed sowing – seed structure Three parts to a seed Seed coat Endosperm Embryo ‘A seed is a plant in a box with it’s lunch’ Seed Sowing Menu

Seed sowing – seed structure Seed coat -the outer covering of a seed helps protect the embryo from injury and drying out. Seed coats can be thin and soft as in beans or thick and hard as in walnuts or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These are often the first parts visible when the seed germinates. Embryo – the ‘baby’ plant. Seed Sowing Menu

Two different situations: Cotyledon(s) appear above ground as first leaves (seed leaves) Cotyledon(s) remain below the ground

Seed sowing – Seed Structure There are two types of plants that produce seeds: Monocotyledons and Dicotyledons Seed Sowing Menu

Seed Structure Seed Sowing Menu

Germination Starts when the seed begins to absorb water Ends when the new plant is able to get all its’ energy from photosynthesis.

Germination – the process The seed absorbs water until it swells and smoothens its exterior wrinkles. Swelling continues until the coat of the seed bursts open. Food stored in cotyledons or endosperm soaks up water and soluble substances dissolve in it. Respiration begins thus energy and raw materials are supplied by food for cell division and growth. A radical appears first and then a pumule.

Respiration During respiration (in plants and animals) energy is released from sugar (glucose) by a series of chemical reactions. The sugar is broken down into carbon dioxide and water in a process which uses oxygen.

Respiration in seeds INPUTS OUTPUTS

Seed requirements List the inputs all seed require to germinate Match your list to the following. Allows seed to swell and break seed coat Required for respiration Speeds up the various chemical processes

Seed dormancy Dormant seeds are seeds that are still alive but when the seed is supplied all that it needs to germinate, - it doesn't. The seed is asleep, waiting for the proper time to awaken. Seed dormancy aids a species' survival by delaying germination so that 'overall germination' is dispersed over time.

Seed Storage Germination needs water. warmth and oxygen Seed storage needs (the opposite) Cool and dry! Why can we not store seeds in a oxygen free environment?

Seed Sowing Summary Seeds don’t get re-assessment opportunities. Once they begin to germinate they either survive or die. Seeds need the WOW factor to survive (water oxygen, warmth). Soil, light, CO2 are only for ‘grown-up’ seeds A seed is a plant in a box with it’s lunch – but no dinner – if a seed is in the packet too long it will run out of lunch and die.

Sexual Propagation – Exercise Which of the following statements are true T/F If we collected 1000 seeds from one kowhai tree, it is unlikely that any one seed will have the same genetic material A sunflower produces 800 seeds. The genetic material in each seed has come form two parents Seed is made after a pollen grain and an egg (ovum) have joined together in a flower Seed is spread by bees and other insects in a process known as pollination A Flower contains both the male and female sexual organs of a plant.

End – Seed Sowing Back to Main menu

cuttings Stem cuttings are the second most widely used form of propagation in horticulture. (Number one is seed)

Semi- hardwood cuttings of Forsythia Leaf cuttings of petunias Hardwood cuttings of grape vines Tip (softwood) cuttings of Hydrangeas

Division Examples of Asexual Examples of Sexual

Grafting Examples of Asexual Examples of Sexual

Layering Examples of Asexual Examples of Sexual