Transcript Chapter 11

Plant Production
Conditions for plant growth
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All plants need water, nutrients & oxygen to grow
Normally plants can spread their roots to take these in
from the soil
Potted plants have limited space for their roots to grow
Potting compost helps to hold more water, air and
nutrients
Rooting compost is good for drainage
Various materials in potting composts
Loam based compost – has good garden soil
Loamless compost – has a lot of peat
Rooting compost – to help cuttings to root
- lots of sand (perlite)
Nutrients
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Absorbed by roots from
soil/compost
Also known as minerals
Some are major nutrients:
- Nitrogen (N) – helps leaves
grow
- Phosphorus (P) – helps roots
grow
- Potassium (K) – helps
flowers/fruits grow
Some are trace nutrients:
- Iron, Magnesium
Fertiliser
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Contain extra supplies of nutrients
Can be added to soil/compost
Have different quantities (ratios) of each
mineral
E.g. 4:2:1
4%Nitrogen, 2%Phosphorus,
1%Potassium
Some are multi-purpose – same ratio of
all
Some are specific
- e.g. fertiliser for leaf growth (more
Nitrogen)
Can be applied as powder, liquid or
granules
Watering
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Plants need different amounts of
water
There are many methods of
watering:
House Plants
From above (with a watering can)
From below (standing pot in a tray
of water)
Garden Plants
A hose (sometimes with a
sprinkler attached)
Automatic watering methods
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Automatic Irrigation
Water from above through
tubes and nozzles
Capillary Matting
Water from below through a
soaked mat
Water Retentive Gel
Within the compost – can
hold water for a long time
Environmental Conditions Temperature
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Each plant has an optimum
temperature
Plants can be shielded from
bad weather
- in a greenhouse
- in a polythene tunnel
A heater can set temperature
- can be controlled by a
thermostat
- a minimum/maximum
thermometer shows the range
of temperatures over 24 hours
Humidity
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How much water vapour is in the air
Plants lose water by evaporation
- to cool the plants
If air is humid (damp), less evaporation
If air is dry, more evaporation
Relative humidity allows air humidity to
be compared
- 75% is high humidity / 20% is low
humidity
Warm temperatures allow higher
humidities
A hygrometer can measure humidity
Ventilation
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Greenhouses must be ventilated
Avoids damp, stale air building up
Autovents
- attached to windows
- have wax cylinders
- as it gets hot, wax expands, vent
opens
Extractor fans
- controlled by thermostat
- switched on if temperature gets too
hot
Wind
- increases evaporation from leaves
- plants can be shielded from the
wind (windbreaks)
Plant Maintenance - cacti
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Have a fleshy stem – water storing
(succulent)
Many stems have sharp spines
Do not have leaves
Desert cacti need direct sunlight &
well-drained soil
Jungle cacti need a little shade & well
drained soil
Both need warm summers & cool
winters
Other succulent plants e.g. aloe have
leaves
Plant Maintenance -ctd
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Ferns
- non-flowering
- prefer humid, cool, dimly lit
conditions
Foliage plants
- house plants grown for their leaf
shape/colour
- prefer well lit, well watered
conditions, with feeds of fertiliser
Flowering Plants
Grown for their attractive flowers
- perennial plants can re-grow
flowers every year
Maintaining Plants
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Pricking Out
Sown seeds often too close together
Seeds could compete for root space,
water, light
Need to be re-planted elsewhere
This is pricking out
Happens when first set of leaves open
out
Potting On
Moving a plant into a bigger pot
Plant is moved when it becomes potbound/root-bound
Dead Heading
Removing dead flower heads
Pests & Disease
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Pest – animal that damages a
plant
- E.g. aphid (greenfly)
- suck out plant’s sugary sap
- often attack shoots & flower
buds
Disease – caused by microorganism
E.g. grey mould
- grows on leaves, then spreads
to other parts
- prefers damp, airless conditions
Controlling pests & disease
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Aphids
- 1) chemical control
- e.g. pesticides or insecticide
- 2) biological control
E.g. ladybirds
- some don’t use chemicals – pick
them off or wash with soapy water
Grey Mould
- plants sprayed with a fungicide
- burning all infected crops / better
ventilation
Protecting Cultivation
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Exposed plants can be
damaged by many things
E.g. wind, rain, low temps,
frost
Plants may need to be
protected:
Glass
Plastic
Polytunnels
Floating Fleece