1 Growing Plants from Seeds

Unit 1: Learning outcomes

Below are lists of things you should know. Read though them and put a red dot in the box beside outcomes you do not know anything about, orange dots beside the outcomes you remember a little about and green dots beside the outcomes you fully understand and know.

The outcomes which have a red or orange dot beside them are the ones you need to try to find out more about or learn.

1 Growing plants from seeds.

i Seed biology.
Simple seed structure:
embryo root and shoot (which grow into the new plant),
food store (for growth)
seed coat (protects the seed).
ii Germination.
Germination is growth of embryo and use of food reserves.
A suitable temperature, water and oxygen are required for germination to take place.
Dormancy means germination is delayed until the spring when the soil temperature rises.
iii Photosynthesis is the process of food production in sunlight.
The food produced by photosynthesis is used for growth. No further detail of photosynthesis raw materials and products is required.
iv Growing plants from seeds.
Methods of seed sowing.
Spacing of seeds: individual sowing of large seeds, mixing of fine seeds with silver sand before sowing.
Pelleted seeds are fine seeds enclosed in a ball of clay.
Pelleted seeds take longer to germinate than non- pelleted seeds and require more water.
Seeds with thick seed coats are pre- germinated (chitted) before sowing.
Thickseed coats are slit or cracked to allow germination.

2 Vegetative propagation.

i Plant propagation structures.(propagation mean producing new plants)
Use of food storage organs such as bulbs and tubers.
Use of attached offspring such as runners, offsets and plantlets.
Runner is a horizontal stem with a plantlet at the end.
An offset is a small plantlet produced as a side shoot at the base of the parent plant.
A plantlet is a miniature plant attached to the parent plant.
ii Artificial propagation.
Growing points.
Nodes are points of plant growth.
Growth is a response to wounding.
Rooting powders promote the development of roots in cuttings.
Techniques of taking stem and leafcuttings.
Methods of reducing water loss to include:
reducing leaf surface area or by increasing humidity by enclosing cuttings or by placing cuttings in a mist propagator.
Layering and its advantages.
Layering as pegging down stems into soil until roots form at nodes.
The advantages of layering include the production of larger plants, better success with plants which are difficult to propagate from cuttings.
The advantages and disadvantages of heat during propagation.
Advantages include faster growth and prevention of frost damage.
Disadvantages include high water losses leading to wilting, higher energy costs and faster growth/ spread of diseases.

3 Plant production.

i Conditions for plant growth.
Loam and loamlesscomposts.
Loam (nutrients); peat and peat substitutes (water retention); grit, sand and perlite (improve drainage).
Properties of granular and liquid fertilisers. Granular fertilizers release nutrients slowly and last longer; liquid fertilisers work faster but don’t last for as long
Mineral ratios in fertilisers. The importance of trace minerals N, P and K as major plant minerals for leaf (N), root (P), flower and fruit growth (K).
Watering to supply sufficient moisture by: watering can, hose or others including use of capillary matting, water retentive gel and automatic irrigation systems to provide water; signs of over and under watering.
Heating and ventilation.
Ways of providing heat in greenhouses and polythene tunnels include electric heaters and gas or oil fuelled stoves.
Thermostats to control temperature.
Ventilation is needed to circulate air.
Types of ventilation include fans and automatically opening windows.
ii Plant maintenance.
The needs of mature plants.
Include: water, light, temperature, humidity with examples from cacti (need low moisture), ferns (need shade), foliage (need high moisture) and flowering plants (need light).
Methods of maintaining plants include:
dead heading (removal of dead flower heads which encourages plant to continue to flower);
pricking out (removal of seedlings to provide less crowded growing conditions),
potting on (placing growing plant into larger container).
Plants need potting on if the roots fill the pot and grow out of the holes in the bottom.
Methods of controlling pests and disease include:
insecticides, pesticides, fungicides, soapy water, biological control, crushing pests and burning affected plants.
The aphid and grey mould as examples of a common pest and a common disease.
Protected cultivation under glass, plastic and floating fleece.
Advantages include: protection from low temperatures, wind, rain, and pests.