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.

http://www.southernbulbs.com/blog/uploaded_images/PrimoBulbsHAndsSB-767737.jpg

Tubers

Factors that influence

how plants grow