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Growth and Development
of Plants
Why would you want to know what
controls the growth and development
of plants?
•Manipulate plant growth, and predict
production.
•Genetically modify plants to increase
productivity or quality.
•Determine the effects of pests and diseases
on plant growth to develop natural resistance.
•Determine how plants grow to discover
ways to kill them (herbicides).
What does a plant have to
do to survive?
•Produce energy from the sun,
photosynthesis.
•Uptake water and nutrients from the roots.
•CO2 and O2.
•Ability to reproduce, Sexually or
A-sexually.
•Defense against pests and stress factors.
What has an impact on a plant’s
ability to grow?
•Genotype.
•Environment:
•Light, temperature, water, soil.
•Pests and diseases:
•Insects, diseases, animals (people).
• Cell wall: provides protection and structure.
• Plasma membrane: controls movement of minerals, metabolites and water into and out of the cell.
• Chloroplast: site of photosynthesis, starch biosynthesis and starch accumulation.
• Golgi apparatus: site of synthesis of polysaccharides such as hemicellulose needed for cell walls.
• Mitochondria: site of all biochemical reactions of respiration.
• Endoplasmic reticulum: site of protein synthesis.
• Vacuole: site for storage of proteins.
• Nucleus : site of the majority of the genetic information (DNA) and is the site of transcription
Plant Cells
• Ground tissues:
–Parenchyma;
–Collenchyma;
–Sclerenchyma.
• Dermal tissues:
–Epidermis;
–Stometes;
–Hairs/tricomes.
• Vascular tissues:
–Phloem;
–Xylem.
Diploid (2n)
somatic cell
Two diploid (2n)
somatic cells
Pro
ph
ase
M
etap
ha
se
An
ap
ha
se
Tel
op
ha
se
I
I
I
I
II
II
II
II
Homologues
condense and
cross over
Homologues
a line
Homologues
separate
Hom
olo
gu
es separa
te
into
2 cells
One pair of
homologous
chromosomes
(homologues)
The cells in the newly formed zygote will
divide and differentiate to produce the
embryo
The embryo organizes into an embryo axis
With a shoot meristem (plumule) and a root
meristem (radicle).
The cells in the endosperm will divide to produce cells that will store energy for the seed to utilize when it germinates.
In dicots the endosperm may be used
to produce the cotyledons that then
serve as an initial energy source for a
germinating seed. An example of this
is a bean seed
Self-pollinator Out-pollinator
Sexual Reproduction
Self-pollinating:
Tolerant to inbreeding
Few deleterious recessive alleles
“Closed” flowers
Little heterosis
Out-pollinating:
Intolerant to inbreeding
Many deleterious recessive alleles
Flower morphology that promotes cross pollination.
High heterosis
Self-pollinator Out-pollinator
• Pure-line inbred cultivar.
• Multi-line cultivar.
• Out-pollinated population cultivars
• Hybrid cultivars
• Synthetic cultivars
• Clonal cultivars.
Flowers
• Grown under strict
quality standards
• Inspected and tagged
by state certification
authorities.
• Genetically pure.
• Free from weeds.
• Free from seed borne diseases.
• Better for agriculture, better end product.
Certified Seed
Cultivation
Land Preparation
• Adopt an appropriate tillage system.
• Maintain an appropriate supply of
organic matter.
• Maintain a prober supply and balance of
nutrients.
• Control soil pollution.
• Maintain proper soil reaction of pH.
• Control soil degradation.
Conventional Tillage
• Primary tillage.
–Topsoil is plowed to a depth of 6
to 14 inches (15-36 cm).
–Aim is to remove crop stubble and
control weeds.
–Implements include: Moldboard
plow; Disk plow and Chisel plow.
Moldboard Plow
Chisel Plow
Moldboard Plowing
Chisel Plowing
Disc Plow
Conventional Tillage
• Secondary tillage.
–Aim to maximize seed-soil contact
at planting.
–Includes disc-ing and harrowing.
–Often associated with application
of granular fertilizers and pre-
plant incorporated herbicides.
Disc Cultivators
Harrow Cultivators
Conventional Tillage Advantages
• Causes compaction, but can manage soil
compaction.
• Easier to fertilizer and seed, good seed-
soil contact.
• Tilled soil heats quicker in fall and spring
for quicker seedling development.
• Lack of residue on soil surface reduced
overwintering of pests (green bridge).
Conventional Tillage Disadvantages
• Erosion, due to lack of surface
residue.
• Soil compaction.
• Costs, more fuel.
• Reduced soil organic matter over
time.
• Moisture loss.
Soil Erosion by Water (tons/acre/year)
October
4, 2009
Soil Erosion by Wind (tons/acre/year)
Direct Seeding
Reduced grower inputs.
Reduced fuel emissions.
Avoids soil erosion.
Improved soil structure.
Avoids soil compaction.
Improved water holding.
More earth worms.
Conservation tillage Advantages
Highly dependant on chemical control, particularly
weeds.
Can involve high investmant costs in seeders.
High risk of crop loss due to pests and diseases.
High residues can impact seedling establishment
Low yield - initially.
Conservation tillage Disadvantages
Seed Drills
Double Disc
Drills
Air Seed Drills
Direct seed drills
Seed Treatments
• Germination
enhancement
• Fungicides
• Insecticides
Non-Treated Seed Treated Seed
Rhyzoctonia Damage
Makes seed handling, and
seed placement easier
Pesticides can be
incorporated into pellet
Pelletization
Monosem Vacuum Drill
Stanhay Belt Drill
Transplanting
Types of clonal propagation
Budding and grafting onto various root
stocks: Rosaceous top fruits, citrus, avocado, grape.
Leafy cuttings: Pineapple, strawberry.
Leafless cuttings:
Sugar cane.
Tubers, bulb, etc.: Potato, various bulb flowers, sweet potato.
Tubers
Factors that influence
how plants grow