2. Plant movements occurs
*At very slow rate
*Only organs move
*By external or internal stimuli
*Based on nature of stimulus may be i)
Spontaneous(autonomic) ii)induced (paratonic)
4. ⦿Movement of plant towards
the stimulus is called tropic
movement .
* direction of stimulus
determines direction of
response & movements
Irreversible growth
5. ⦿ Phototropism – Movement of
plant towards light is called
phototropism.
Coleoptile bend towards light by
auxin action
⦿Shoot grow towards light.
⦿Shoot is positively phototropic
while root is negatively
phototropic .
(Climbers)
6. ⦿Movement of plants in response to
gravity is called geotropism .
⦿Roots are positively geotropic and
shoots are negatively geotropic .
But respiratory roots of
mangroves tree - negatively
geotroohic
7. ⦿Growth of plants towards water
is called hydrotropism .
⦿Roots grow towards water.
8. ⦿Movement of plants
towards chemicals is
called chemotropism .
⦿Growth of pollen
tube towards c
h
e
m
i
c
a
l
s
s
e
c
r
e
t
e
d
b
y
ovule is an example
of chemotropism.
Postively
chemotrophic -
bryophytes
9. ⦿Nastic movement is not a
directional movement of
the plant part with response to the
stimulus. Reversible
Neither away nor towards stimulus
In nastic movement, from
whichever direction the stimulus is
applied, it affects all the parts of
the organ of a plant equally and
they always move in the same
direction .
37. ⦿Phyto hormones
• signal molecules, organic substances
produced within plants
• occur in extremely low concentrations.
• control all aspects of plant growth and
development, from embryogenesis to
regulation of organ size, pathogen defense,
stress tolerance and reproductive
development.
39. . Auxin was isolated
from human urine
. Discovery of auxin - Charles Darwin -
phototropism in coleoptile of canary grass
. F.W.Went - Avena curvature test in oat seedings - using
agar and isolated auxin with its function
40. First phyto hormone, discovered by charles
darwin and most important
2 types -
1) Natural Auxins - IAA, IBA
2) Synthetic Auxins - NAA, 2 4 D
41. * Present in root tip and shoot tip
* promote flowering
* Induce apical dominance and inhibit later bud
growth
*Induce parthenocarpy (seedless fruits)
* Promote cell differentiation(xylem) and cell
enlargement
* used as herbicide to kill dicot weeds - 2,4D
* It initiate root in plant tissue culture method
and propagation in stem cuttings
Physiological effects of auxin
42.
43. GA - first gibberellin discovered is gibberellic
acid. GA1, GA2,....GA100
Physiological effects of auxin
* Delay senescence
* Speeding up of malting process in brewing
industry
* promotes bolting process
(sudden internodal elongation) in rosette plants in
beet and cabbage and length of grapes stalks
*Sprayed in sugarcane to increase stem lenngth
*cell enlargement and elongation of fruits etc
44.
45. * Cytokinins (CK) promote cell division, or
cytokinesis, in plant roots and shoot
(plant tissue culture)
* promote morphogenesis
* opening of stomata, fruit growth
*break bud and seed dormancy
* Zeatin - coconut milk (Coconut water
contain cytokinin)
* helps in producing new leaves,
chloroplast, lateral bud growth and
adventitious
shoots
* help in overcome apical dominance
Physiological effects of cytokinin
46. * ABA - inhibitor of plant metabolism
* Regulate abscission and dormancy
* inhibit seed germination, development and
maturation
* Called stress hormone - stimulate closure of
stomata - stress tolerance
* antagonist to GA
Physiological effects of abscisic acid
47. It acts as a growth promoter as well as
inhibitor. It is a simple gaseous
hormone . Fruit ripening.
48.
49. 1.Stimulating fruit ripening and increase respiration rate -
tomato and citrus fruits
2.Helps in determining the sex of a flower. Induce flowering
in mango tree
3.It is involved in the production of female flowers in a
male plant.
4.Promotes abscission and senescence of both leaves and
flowers
5.Helps in the root initiation and pollination.
6.Ethylene increases the speed of leaf and flower
senescence.
7.Induces seed germination.
8.Induces root growth and root hair formation
9. to increase the capability of water and mineral
absorption.
10. Promotes sprouting of potato tubers
11.Break dormancy of seeds and buds
Physiological effects of ethylene
