pbl presentation plant physiology
TRANSCRIPT
PBL PRESENTATIONLECTURER : DR. HASIMAH ALIMON
NURUL SYUHADA BT. ISHAKD20091034862PUI WAN TINGD20091034840
NORAZLIN BT. SALAHUDDIN ABDUL AZIZD20091034847
NUR IZZAH BT. IBRAHIMD20091034874
GROUP MEMBERS
WHAT IS PLANT GROWTH?Plant growth is the process by which a plant
increases in the number ,size and length of
leaves, stems, roots and tubers.
WHAT IS PLANT DEVELOPMENT?
Plant development by which plant structures
originate
and mature as a plant grows.
TYPE OF PLANT GROWTH AND
DEVELOPMENT
LEAVELEAVESS
TUBERTUBERSS
ROOTSROOTS
STEMSSTEMS
LEAVESLEAVESLEAVESLEAVES
WHAT ARE THE FUNCTIONS OF LEAVES?
Absorb sunlight to manufacture plant sugars through a process called photosynthesis.
The cuticle is part of the epidermis. It produces a waxy layer called cutin, which
protects the leaf from dehydration and disease.Special epidermal cells called guard cells
regulate the passage of water, oxygen, and carbon dioxide into and out of the leaf through tiny openings called stomata.
The Growth and Development of Leaves
The first leaves to develop are the unifoliolate
leaves.
Two of these single leaves appear directly
opposite one another above the cotyledons.
All subsequent leaves are
trifoliolates
comprised of
3 leaflets.
THE GROWTH AND DEVELOPMENT OF RICE LEAVES
A leaf primordium is differentiated
from a little below the shoot apical
meristem (SAM).
As it develops, it elongates and forms
a cone-shaped structure around the
SAM.
Soon after, smaller veins start to form
on both sides of its base, and later in
between larger veins.
When the primordium has grown to about 8
mm, a cavity develops at its base.
The auricles and the ligule will be
differentiated from this location, which will be
differentiated into the collar.
The collar separates the blade and the sheath.
After the cavity has formed, the meristem
that is responsible for elongation is activated
and the blade starts to elongate.
Now the blade has grown to its full size, and
its cells have stopped dividing, the blade is
ready to emerge.
As the blade emerges, it unrolls from its tip
down to the base.
As it unrolls, cells in the blade expand to
reach a larger size.
The figure on the left is a cross section of a young rice shoot showing a rolled-up leaf blade being enclosed by an older leaf sheath. The figure on the right demonstrates the location of the sheath "1" and the young blade "2".
This is why an older leaf is wider and longer
that a newly emerged leaf not because it has
more cells, but because its cells have grown
larger.
As soon as the blade starts to expand, the leaf
sheath starts to elongate.
The sheath completes its elongation when the
blade has fully expanded.
ROOTSROOTS
WHAT ARE THE FUNCTIONS OF ROOT
Anchor the plant in the soil.
Store food.
Absorb water and mineral salts
from the soil.
Form a passage way for water and dissolved
substances from the root into the stem and also
for foods from the stem down into the root.
The Growth and Development of Root
Early root growth is one of the functions of
the apical meristem located near the tip of
the root.
The meristem cells more or less continuously
divide, producing more meristem, root cap
cells and undifferentiated root cells.
The latter become the primary tissues of the
root, first undergoing elongation, a process
that pushes the root tip forward in the
growing medium.
Gradually these cells differentiate and mature
into specialized cells of the root tissues.
Growth from apical meristems is known as primary
growth, which encompasses all elongation.
Secondary growth encompasses all growth in
diameter, a major component of woody plant
tissues and many nonwoody plants.
For example, storage roots of sweet potato have
secondary growth but are not woody.
Secondary growth occurs at the lateral meristems,
namely the vascular cambium and cork cambium.
THE GROWTH AND DEVELOPMENT OF SOYBEN ROOT
As soybean seed takes on the water
and swells, the radical is the first
part of embryo to penetrate the seed
coat .
It develops rapidly into a root which
must become firmly anchored for
seedling to develop enough leverage
to force its way to the soil surface.
Lateral roots are formed soon after the radical or
primary root begins to elongate.
Root hair appear on the primary root within 4 or
5 days after germination and on the lateral roots
soon after they are formed .
These hair are the main absorbing surface of the
root system.
They are very small nearly invisible without a lens
and might be extensions of single epidermal cells.
They are actively growing part of the root just
behind the growing point.
What condition did root grow?
Roots will generally grow in any direction
where the correct environment of air, mineral
nutrients and water exists to meet the plant's
needs.
Roots will not grow in dry soil.
At germination, roots grow downward due to
gravitropism.
What are the functions of stem ?
serves as mechanical support for leaves and buds.
Water and food storage.
Reproduction
Photosynthesis
New growth
Types of growth and development in stem
Primary stem growth :-o begins at the tip of the terminal bud in the area
called the apical meristem. o The cell divisions on the apical meristem are
responsible for the stem's growth in length. Secondary stem growth :-
o Also known as secondary thickening or lateral growth arises from secondary meristems.
o Secondary xylem and secondary phloem are formed.
o Stems are tend to thickening.o Cambium is developed at the outer part of the stem.o More stronger than primary stem.
Stem terminologyStem terminologyShoot (a young stem [1 years old or
less] with leaves)
twig (A young stem [1 year old or less] that is in the dormant winter stage with no leaves.)
branch (A stem that is more than 1 year old, typically with lateral stems radiating from it)
(A woody plant's main stem)trunk
Types of stems:Specialize above ground stems:
o Crowns ( strawberries) o Spurs (apple, cherry trees)o Stolons ( strawberry runners)
Specialized below-ground stemso Rhizomeo Bulb
Tunicate - thin, papery covering; protection to the bulb from damaging and drying during digged out from the soil.
Nontunicate – do not have papery cover.o Cormo Tuberous stem
What are the functions of tubers? food storage
reproduction
Types of growth and development in tubers
Stem tubers are formed from the thickening of rhizomes or
stolons.Exp:- potato tubers are developed from thickened
stolons or known as propagation.
Root tubersEnlargement of modified lateral roots and
budding.
Types of tubers:There are 2 types of tubers:
i. Stem tubers
ii. Root tubers
MECHANISM OF GROWTHSeed germinationPhotosynthesisPlant hormones
MECHANISM OF MECHANISM OF GROWTHGROWTH
SEED GERMINATIONGermination is the process in which a plant
or fungus emerges from a seed or spore and begins growth.
example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm.
of a sporeling from a spore, for example the growth of hyphae from fungal spores, is also germination.
MECHANISM OF MECHANISM OF GROWTHGROWTH
PHOTOSYNTHESISa process that converts carbon dioxide into
organic compounds, especially sugars, using the energy from sunlight.
the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls.
MECHANISM OF MECHANISM OF GROWTHGROWTH
also known as plant growth regulators (PGRs) or phytohormones,
are chemicals that regulate plant growth.Plant hormones are often not transported to
other parts of the plant and production is not limited to specific locations.
occur in extremely low concentrationsPlants lack glands that produce and secrete
hormones, instead each cell is capable of producing hormones.
affect gene expression and transcription levels, cellular division, and growth.
Auxin (IAA)CytokininsGibberellinsBrassinosteroidsAbscisic Acid (ABA)Ethylene
Auxin (IAA)are class of plant growth substance and
morphology (often called phytohormone or plant hormone)
On the molecular level, auxins have an aromatic ring and a carboxylic acid group
Function:Primary site of synthesis in shoot apical
meristem and young leaves.influence cell enlargement, bud formation
and root initiation.in conjunction with cytokinins, they control
the growth of stems, roots, and fruits, and convert stems into flowers.
Stimulate stem elongation and promotes the formation of lateral and adventitious roots.
Regulates development of fruit.
CytokininsSynthesized primarily in the roots and
transported to other organs.-promote cell division and organ development,
but impede senescence. influence cell division and shoot formation.Modify apical dominance and promote lateral
bud growth.Promote movement of nutrients into sink
tissues.Stimulate seed germination.Delay leaf senescence.
GibberellinsSite for production in meristems of apical
buds and roots, young leaves and developing seeds.
Stimulates stem elongation, pollen development, pollen tube growth, fruit growth, and seed development and germination.
Regulate sex determination and the transition from juvenile to adult phases.
control cell expansion,
BrassinosteroidsPresent in all plant tissue at different
intermediates predominate in different organs.
Promotes cell expansion and cell division in shoot, at low concentration promote root growth.
Promote xylem differentiation but inhibit phloem differentiation.
Promote seed germination and pollen tube elongation.
Abscisic Acid (ABA)Almost all plant cell can synthesize ABA.Inhibit growth.Promotes stomatal closure during drought
stress.Promotes seed dormancy and inhibit early
germination.Promotes leaf senescence and desiccation
tolerence.
EthyleneCan be produce by almost all plant parts. Promotes ripening of many types of fruit, leaf
abscission and the triple response in seedlings (inhibition of stem elongation, promotion of lateral expansion and horizontal growth).
Enhances the rate of senescence.Promotes root and root hair formation.
LEAF SENESCENCE
DESICCATION TOLERENCE
LEAF ABSCISSION
THANK
YOU