Plant hormones

plant hormones

coordinate and control growth
respond to light and gravity

phototropism

response to light

dark side

where auxin collects in response to light, causing it to grow faster

gravitropism or geotropism

response to gravity

auxin in shoots

cell elongation is stimulated

auxin in roots

cell elongation is slowed, inhibited

auxin

plant hormone

unequal distributions of this cause unequal growth rates in plant roots and shoots

hormone production occurs here

tips of shoots and roots

gibberellins

are important in initiating seed germination

ethene

controls cell division and ripening of fruits

if the tip is covered (opaque cap) or cut off...

...no auxin produced
...no response to light

auxin can be used as...

...a weedkiller(targets broad leave plants)

…rooting powder for growing cuttings

…growing cells in tissue culture

ethene can be used as...

...a ripening agent

gibberellins can be used as...

...a way to end seed dormancy

…inducing flowering

…growing larger fruit

shoots + gravity

• shoots grow away from gravity

• more auxin on lower side

• grows faster

required practical

1. put ten cress seeds into 3 different petri dishes, label A B C

2. A = direct light, B = left side C = right side

3. leave for one week, see it growing towards light

what does gibberellin stimulate

seed germination, stem growth + flowering