POLLINATION and FERTILIZATION Review
Pollen
POLLINATION ReviewSelf pollination and Cross pollination
FERTILIZATION ReviewFertilization Basics
FERTILIZATION ReviewPollen grain with
nucleiPollen grain with
pollen tube nucleus (1) and sperm nuclei (2)
FERTILIZATION Review
FERTILIZATION Review
ZYGOTE to EMBRYO
SEEDSMORPHOLOGY
SEED COAT (testa) HILUM MICROPILE
ANATOMY EPICOTYL HYPOCOTYL RADICLE
FOOD SOURCE COTYLEDONS – dicots ENDOSPERM – monocots
SEED GERMINATIONSTEPS to GROWTH
SEED imbibes WATERSEED COAT BURSTS (more O2 + H2O)EMBRYO produces HORMONES (Gibberellic Acid)
which activate ENZYMES (alpha-amylase) converting STARCHES to SUGARS and transported to the EMBRYO
RESPIRATION STARTS > ENERGY > produces new CELLS, TISSUES and GROWTH
RADICLE emerges (germination)HYPOCOTYL and EPICOTYL emerge
SEED GERMINATION
CONDITIONS for GERMINATION
VIABLE SEEDFavorable ENVIRONMENTAL conditionsFavorable INTERNAL conditions
The seed is said to be DORMANT, if seed is VIABLE and one or more conditions is not met.
CONDITIONS for GERMINATIONVIABLE SEED
Dependent on SPECIES
VIABILITY prolonged by: COOL temperatures Low HUMIDITY (low H2O)
Low O2
CONDITIONS for GERMINATIONFavorable ENVIRONMENTAL conditions
H2O Saturated vs. not saturated
O2 Dry, sandy vs. clay soils
TEMPERATURE Cool vs. warm season crops
LIGHT Light – celery, lettuce, weeds No light - peas
CONDITIONS for GERMINATIONLIGHT
Pigment PHYTOCHROME Blue-green pigment Exists in two forms Pr (660 nm) Pfr (730 nm)
Amount of Pr or Pfr in tissues is determined with the type of light present
CONDITIONS for GERMINATIONFavorable INTERNAL conditions
PHYSICAL barriers Seed coat IMPERMEABLE to H2O Seed coat RESISTS EXPANSION
Remedy SCARIFICATION: MECHANICAL CHEMICAL TEMPERATURE
CONDITIONS for GERMINATIONFavorable INTERNAL conditions
PHYSIOLOGICAL barriers IMMATURE EMBRYO
Remedy – TIME
AFTER RIPENINGRemedy – STRATIFICATION:
Application of MOISTURE and LOW TEMPS or alternation
Usually due to Abscissic Acid and low temperatures
CONDITIONS for GERMINATIONFavorable INTERNAL conditions
CHEMICAL barriers
INHIBITORS in SEED COAT Remedy – LEACH with WATER
Desert seeds - Phenolic acid
INHIBITORS in FRUIT Remedy – SOAK and REMOVE PULP
Tomatoes, Arisaema triphyllum
SEED DORMANCYInsures GERMINATION during times that
maximize SURVIVAL of SEEDLINGS
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