Download Water Wise Gardening Lesson Notes

Water Wise Gardening
Poster 1
Lesson Notes
RAND WATER
RAND WATER
Water Wise Gardening Poster
1. HOME/SOIL
2. LIGHT
3. WATER
4. FOOD
5. AIR
1 2
5
3 4
POSTER 1
Lesson 1
LIMITING FACTOR PRINCIPLE
Not only do plants need a home/soil (habitat), light, water, air and food, but they also
need to have these factors in the correct amounts. They need the right balance of each
in order to grow efficiently. This is called the LIMITING FACTOR PRINCIPLE which
states that, “too much or too little of any biotic factor can limit or prevent the growth of
an organism, even if all other factors are at or near the optimum level”.
So, for example, if a gardener plants a plant in an area where it receives too little light, it
will not grow, even if there is enough water, air, food and soil (warmth/home
environment) for the plant. If the plant receives enough light, water, air, and soil but too
little food, it will also not grow to its full potential. If a plant is given lots of water, but has
too little food, it will be unable to use all the water. This is because its growth will be
limited by the amount of food available, and the water has been wasted!
The principles of caring for plants should not be overwhelming. Humans and plants
have many areas of common ground. On the following page are a few examples, can you
find more?
Water Wise Gardening - Poster 1 - Lesson 1 - Page 1
NEW
HOME
For survival a plant needs...
For survival we need...
A home or habitat with the right
combination of environmental factors
(like temperature and moisture) in
w h i ch t h e p l a n t c a n g r o w a n d
reproduce.
A home which provides us with shelter
and security.
Light - sunlight is the energy source that
plants use to produce carbohydrates
through the process of photosynthesis.
The sun’s energy provides warmth. The
action of sunlight on the skin produces
Vitamin D. Sunlight can improve
people’s moods.
Water - makes up about 90% of plant
cells. It provides mechanical support to
cells and tissues. Water is needed for all
metabolic reactions. Water is the
solvent in which other molecules can
dissolve and be moved around the plant.
Plants lose water through
transpiration.
Water makes up 70% of the human body.
It is needed for digestion and absorption
of food and for getting rid of wastes.
People also use water for bathing,
washing and cleaning and carrying
wastes away from their homes. People
lose water through respiration.
Air - contains a mixture of gases
including carbon dioxide and oxygen.
Carbon dioxide is absorbed by plants
through their leaves and is used to make
food t hrough t he process of
photosynthesis. Oxygen is produced
during photosynthesis and is released
into the air through the leaves. Plants
also use oxygen to break down food
molecules like sugars (this process is
called respiration).
When we inhale, our lungs absorb the
oxygen in the air and this is used to
break down the food stored in our cells,
releasing the food energy (this process
is called respiration). The carbon
dioxide that is produced dur ing
respiration is released into the air when
we exhale. Plants are essential in
cleaning the air for humans and thus air
is cycled between man and plants.
Water Wise Gardening - Poster 1 - Lesson 1 - Page 2
Food - Plants are called producers
because they make their own food using
t h e s u n’ s e n e rg y. P l a n t s m a ke
carbohydrates in their leaves and stems
during photosynthesis. But they need to
get other nutrients like nitrates and
phosphates from the soil. Soils contain a
mixture of nutrients that plants take up
though their roots. Plants are at the
bottom of the food chain. No other life
could exist if there were no plants.
Humans cannot make their own food
like plants can. Humans are consumers,
meaning that they get their energy by
consuming either plants or animals. The
food that we humans eat is broken down
in our bodies releasing energy. This is
used for work, growth, and repair of the
body. Humans are at the top of the food
chain.
Note: If we applied too much fertilizer
(food to the roots) at one time and then
left it for a long time, the plant would die.
People are similar eg. a baby will require
small amounts of food at a regular time.
Giving a baby a week’s supply of food at
one time will kill it as the baby is not able
to make use of it all at once.
ACTIVITY
1. Imagine you are
stranded at the back of
the moon. Draw up a list of
things you would need to
survive. See which of these
things correspond to plant
requirements.
2. Can you find any other similarities
between plants and humans.
Water Wise Gardening - Poster 1 - Lesson 1 - Page 3
RAND WATER
For information and ideas on Water Wise gardening call the
Rand Water customer service centre on 0860 10 10 60,
or visit the home and garden section of their website at
www.randwater.co.za
RAND WATER