2.6 Hormones and control of plant growth

Plants produce hormones and respond to external stimuli, growing towards sources of water and light, which they need to survive.

Phototropism, stem will grow towards the light source to optimise production of photosynthesis.

 Gravitropism (also called a 'geotropism'), roots of plant will always grow in the direction of gravity or towards moisture.

Plant hormone called  AUXIN.

Unequal distribution of AUXIN cause unequal growth, resulting in the bending of the root or shoot of a plant.

Uses of AUXIN

·         Used to stimulates fruit growth, help ripens the plants.

·         Used to stimulate root growth of cuttings

·         Used as weed killers to kill any unwanted plants.