Transcript Basics of Plant Growth - Modesto Junior College

Basics of Plant Growth
Chapter 13
Regions of Growth
• Tips of stems and roots
– Terminal buds & root tips = growth in length
• Axils of leaves
– Form new stems, leaves, & flowers
• Cambium layer in stems and roots
– In dicots = growth in diameter
Concepts & Components of
growth
• All living material is made up of cells or
products of cells.
• All cell are derived from previously
existing cells; most cells arise by cell
division, but in sexual organisms they may
be formed by fusion of gametes.
• A cell is the most elementary unit of life.
• Every cell is bounded by a plasma
membrane.
Concepts & Components of
growth cont.
• All cells have strong biochemical
similarities.
• Most cells are small, about .001 cm in
length
• The three general functions of most cells:
– Maintenance
– Synthesis of cell products
– Cell division
Mitosis
• Simple cell division.
• Daughter cells are the same genetically as
the mother cell.
• There are six steps to Mitosis
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Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Sexual Propagation
• If the plant group will reproduce “true by
seeds – with no characteristics changed –
the cultivar is termed a line.
• Inbred lines – used to produce hybrid
cultivars.
• Hybrid – the offspring of two
plants/animals differing in one or more
Mendelian characters.
Sexual Propagation
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Homozygous
Heterozygous
Genotype
Phenotype
DNA
Gene
Chromosome
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Diploid
Haploid
Recessive
Dominant
Mitosis
Meiosis
A = Adenine, T = Thymine, G = Guanine, C = Cytosine
Meiosis
• This will be covered in chapter 15
Basic Genetics
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Gene
Chromosomes
DNA
Double helix bond
– DNA Bases
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Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
How it works
• Since all living organisms are composed of
largely proteins which are made up of
long chains on amino acids.
• There are 20 different kinds of amino
acids found in proteins.
• Instructions from genes are transmitted
indirectly by ribonucleic acid (mRNA)
• mRNA moves from the nucleus into the
cytoplasm
• tRNA serves as a template for protein
synthesis which will translate the codons.
Plant Hormones and Regulators
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Increase profits.
Preventing lodging in cereals.
Preventing preharvest drop.
Synchronizing maturity to facilitate
mechanical harvest.
• Hastening maturity to decrease turnover
time.
• Reduce labor requirements.
Plant Growth Hormones
• Auxins– 1st group of plant hormones to be
discovered, mid 1930’s
– Adventitious root initiation
– Weed control (2-4D)
– Inhibition of stem sprouting
– Tissue culture
Gibberellins•
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Increasing fruit size of seedless grapes
Stimulating seed germination
Seedling growth
Promoting male flowers in cucumbers
Overcoming the cold requirement for
some plants
CytokininsNo important agriculture use at this time.
DNA & RNA
Ethylene
• Fruit ripening
• Flower initiation
• Changing sex expression (female flowers
in cucumbers & pumpkins)
• Degreening oranges, lemons grapefruit
• Harvest aids
Inhibitors
• Abscisic Acid
• Synthetic
• Used to regulate plant growth
Growth inputs & quality
• Timing
• Amounts
Measuring plant growth, How?
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Fresh weight
Dry weight
Volume
Length
Height
Surface area