Photosynthesis in Relation to Light, Temperature and Water

Photosynthesis in Relation to Light, Temperature and Water

Light has three principal characteristics that affect plant growth:

quantity, quality, and duration.

Light quantity refers to the intensity or concentration of sunlight

and varies with the season of the year. The maximum is present in the

summer and the minimum in winter. The more sunlight a plant receives

(up to a point), the better capacity it has to produce plant food

through photosynthesis. As the sunlight quantity decreases the

photosynthetic process decreases. Light quantity can be decreased in a

garden or greenhouse by using shade-cloth or shading paint above the

plants. It can be increased by surrounding plants with white or

reflective material or supplemental lights.

Light quality refers to the colour or wavelength reaching the plant

surface. Sunlight can be broken up by a prism into respective colours

of red, orange, yellow, green, blue, indigo, and violet. On a rainy

day, raindrops act as tiny prisms and break the sunlight into these

colours producing a rainbow. Red and blue light have the greatest

effect on plant growth. Green light is least effective to plants as

most plants reflect green light and absorb very little. It is this

reflected light that makes them appear green. Blue light is primarily

responsible for vegetative growth or leaf growth. Red light when

combined with blue light encourages flowering in plants. Fluorescent

or cool-white light is high in the blue range of light quality and is

used to encourage leafy growth. These lights are excellent for

starting seedlings. Incandescent light is high in the red or orange

range but generally produces ...

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...ntioned earlier, water is a primary component of photosynthesis.

It maintains the turgor pressure or firmness of tissue and transports

nutrients throughout the plant. In maintaining turgor pressure, water

is the major constituent of the protoplasm of a cell. By means of

turgor pressure and other changes in the cell, water regulates the

opening and closing of the stomata, thus regulating transpiration.

Water also provides the pressure to move a root through the soil.

Among water's most critical roles is that of a solvent for minerals

moving into the plant and for carbohydrates moving to their site of

use or storage. By its gradual evaporation of water from the surface

of the leaf, near the stomata, helps stabilize plant temperature.

So, in conclusion, Light, Temperature and water all affect the rate of

photosynthesis.