4. phases of plant growth and development

THE WAY OF PLANT DEVELOPMENT

1. 1
PHASES OF PLANT GROWTH
AND DEVELOPMENT
Involves 3 stages as follows:
Embryogenesis
Fertilization to seed
2. Vegetative growth
1.Juvenile stage
2.Germination to adult
3.‘Phase change’ marks transition
3. Reproductive development
1.Make flowers
2.Can reproduce sexually
VEGETATIVE GROWTH
Growth
1.Product of metabolic processes that takes place in the plant.
2.Growth of living plants is actually the permanent deposition of material which is
utilized by the plant to construct new tissues.
3.Growth is a vital process that brings about permanent and irreversible increase
in size and weight.
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2. 2
SEED
Maintains the continuity of the species
ESSENTIAL FUNCTIONS
1.Reproduction: Most flowering plants reproduce through seed except those that
are vegetatively propagated.
2.Container of the embryo: Seed is a container in which embryo develops and
reaches maturity.
3.Protection of embryo:Embryo remains within the seed and is protected from
excess cold, heat, rain and other natural calamities.
4.Storage of food: Stores food material in the cotyledons are in the endosperm
especially in monocotyledons.
PARTS OF SEED
1. TESTA
Outer layer
2. TEGMEN
Inner layer
3. HILUM
The scar on a seed marking the point of attachment to its seed vessel
4. MICROPYLE
A minute opening in the ovule of a seed plant through which the pollen tube usually
enters
5. RADICLE
The part of a plant embryo that develops into the primary root.
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3. 3
PARTS OF SEED
6. PLUMULE
The young shoot of a plant embryo above the cotyledons, consisting of the epicotyl
and often of immature leaves
7. EPICOTYL
The region of an embryo or seedling stem above the cotyledon
8. HYPOCOTYL
The part of the stem of an embryo plant beneath the stalks of the seed leaves or
cotyledons and directly above the root
9. COTYLEDON
An embryonic leaf in seed-bearing plants, one or more of which are the first leaves
to appear from a germinating seed
PARTS OF SEED
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4. 4
GERMINATION
When seed is provided with
Moisture
proper temperature
and air (oxygen),
the dormant embryo (young plant) starts growing. This process is called
Germination.
Types of Germination
1.Epigealgermination
2.Hypogeal germination
STAGES OF SEED GERMINATION
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5. 5
EPIGEAL GERMINATION
Portion of the axis below the
cotyledons (hypocotyl) grows
relatively fast and pushes the
cotyledons above the surface of the
soil.
Examples: Muskmelons, gourds,
luffa, beans and cucumbers
HYPOGEAL GERMINATION
Portion of the axis above the cotyledons
(epicotyl) grows rapidly and carries the
plumuleabove the surface of the soil.
Examples: Litchi, groundnut, peas, gram
and jackfruit
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6. 6
VEGETATIVE GROWTH PATTERN
Herbaceous plants are small plants with soft stems. Generally classified as follows
according to their life span:
1.Annuals
2.Biennials
3.Perennials
ANNUALS
Those plants which complete their vegetative and reproductive growth in one
growing season.
Examples:All seasonal flowers, cereals, most vegetables and edible oil seed plants
VEGETATIVE GROWTH PATTERN
BIENNIALS
1.They complete their vegetative growth in one growing season.
2.In temperate climates, they produce flowers, fruits and seeds in second growing
season.
3.In tropical climates, they complete their life cycle in one year like annuals.
Examples:Carrot, Radish, Turnip, Cabbage and Beet
PERENNIALS
They survive for many years. Two phases are most important
1.Juvenile phase (Vegetative Phase)
2.Mature Phase (Reproductive Phase)
3.Classified into two categories:
4.Herbaceous perennials
5.Woody perennials
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7. 7
VEGETATIVE GROWTH PATTERN
HERBACEOUS PERENNIALS
Give out aerial shoots from dormant underground stems like rhizome, corms, bulbs and tubers
During unfavorable conditions, aerial parts die except underground parts
During favorable conditions, they repeat the same growth pattern
Examples: Ginger, Turmeric, Arrowroot, Crocus and Saffron tulip
WOODY PERENNIALS
They survive for many years. Can be shrubs or trees. Usually grown as hedges, climbers and
ornamental plants
Examples: Rose, Shoeflower, Night jasmine, Crotons, Duranta, Lantana, Mango, Banyan,
Peepal, Eucalyptus, Pinusand Cedar
REPRODUCTIVE GROWTH
Reproductive growthfavors flowering and fruit formation for development of a marketable
crop.
FLORAL MORPHOLOGY
Floweris the reproductive
phase of the plantwhich is
responsible for the production
of fruits and seeds.
It includes:
1.Calyx (Sepals)
2.Corolla (Petals)
3.Androecium (Stamens)
4.Gynoecium or pistils
(Carpels)
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8. 8
GAMETOGENESIS
The process in which cells
undergo meiosis to form
gametes.
POLLINATION
Transfer of pollen grains from
the anther to the stigma by a
pollinating agent
TYPES OF POLLINATION
1.Autogamy or self pollination
2.Allogamy or cross
pollination
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9. 9
AUTOGAMY OR SELF POLLINATION
The pollination of a flower by
pollen from the same flower
or from another flower on the
same plant.
ALLOGAMY OR CROSS POLLINATION
Cross pollinationis the transfer of
pollen grains from the anther of a
flower to the stigma of another
flowerin adifferent plant of same
or different species.
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10. 10
ADVANTAGES
SELF POLLINATION
It takes place in bisexual flowers, where
both male and female parts mature at
same time and there is great possibility
of fertilization and fruit formation
CROSS POLLINATION
1.Hybrids possess greater adaptability to
the environment
2.Better germination ability
3.Offspring produced are more capable of
surviving
4.Variation is increased
FERTILIZATION
Plant fertilizationis the union of male
and female gametes (reproductive
cells) to produce a zygote
(fertilizedegg).
DOUBLE FERTILIZATION
This process involves joining of a
female gametophyte with two male
gametes
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11. 11
REPRODUCTIVE GROWTH
FRUIT MATURITY
Final stage of development that must take place when the fruit is still attached to
the mother plant
FRUIT RIPENING
1.It involves certain biochemical changes which take place in the fruit after full
maturation. The softening of the edible portion is near completion.
2.It may take place before or after harvesting
3.Physiological changes indicate the termination of the mature stage and the
initiation of senescence of fruit
SENESCENCE
It is a physiological aging activity in which plant tissues degenerate and ultimately
die
TYPES OF SENESCENCE
1. PARTIAL SENESCENCE
Involves the degeneration and death of aerial plant parts like leaves, branches,
flowers, fruits but not underground plant parts e.g. The deterioration of cotyledons
after germination
2. COMPLETE SENESCENCE
Aging process in which all parts of the plant except the seeds ultimately die.
It is observed in most of the pulses, vegetables and ornamental seasonal flowers
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MODIFYING PLANT GROWTH
PHOTOPERIOD
The number of daylight hours
PHOTOPERIODISM
The response of plants to the relative length
of daylight or darkness
CRITICAL LIGHT PERIOD
The dividing line between daylength
favorable to vegetative growth and those
inducing flowering and seed formation
SHOT-DAY OR LONG NIGHTS
PLANTS
Cosmos, Soyabean, Chrysanthemum and
Poinsettia
LONG-DAY OR SHORT NIGHT
PLANTS
Spinach, Althea, Winter wheat and Oats
DAY-NEUTRAL PLANTS
Cucumber, Kidney bean, Pea and Tomato
MODIFYING PLANT GROWTH
Plant hormones
•Natural substances produced by plant tissues in small quantities especially at the
growing points and transported to other regions where they are required to
regulate the activities of the plant.
Plant growth regulators
Synthetic products, which when applied to plants produce reactions almost identical
to those caused by natural hormones
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13. 13
CLASSIFICATION OF PLANT
HORMONES/REGULATORS
Categorized as follows:
1.Auxins
2.Gibberellins
3.Ethylenes
4.Cytokinins
5.Abscisic Acid (growth retardant)
Other plant growth retardants/inhibitors include:
1.Daminozide
2.Chlormequat
3.Cycocel(CCC)
4.Ancymodol
5.Paclobutrazal
FERTILIZERS
Definition:A chemical or natural substance added to soil or
land to increase its fertility.
The two types of fertilizers -Inorganic and Organic
Primary nutrients -nitrogen (N), phosphorus (P), and
potassium (K)
Secondary nutrients -calcium (Ca), magnesium (Mg), sulfur
(S)
Trace minerals-boron (B), chlorine (Cl), copper (Cu), iron
(Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), and
selenium (Se)
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