Download Reproduction of Plants

Reproduction of Plants
Propagation
Sexual and Asexual
• Asexual
– No seeds
– Leaf, stem, or root
• Sexual
– Union of pollen and egg
– Pollination
– Fertilization
• Pollen tube, male gametes unite with egg cell to form
zygote
Pollination
• Transfer of pollen
• Pollen grains
– Pores where pollen tubes grow
• Self – pollination
• Cross – pollination
• Wind or animal
Gymnosperms
• “Naked seeds”
• Conifers or Cone – bearers
• Pollen cones or seed cones
– Seed cones are larger
• Pollination occurs in late spring
• Seed cones stand up on tips of branches and open
slightly
• Ovule produces sticky liquid that pollen gets trapped in
• Pollination complete seed cone turns upside down
Angiosperm
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Flowering plants
Annual or perennials
Ovules develop in ovary
Fertilization
– Pollen lands on stigma
– Pollen tube to enter style
– Enters ovary and sperm is released in ovule
Parts of the Seed
• Hypocotyl
– Connection b/w cotyledon and radicle
• Radicle
– Hypocotyl and embryonic root
• Epicotyl
– Shoot – stems and leaves
• Cotyledons (seed leaves)
• Endosperm
– Stores plant food
• Seed coat
– Outer covering protects embryo
Seed Dispersal
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Ovules develop inside of an ovary
Fleshy part nutritious for animals
Hooks, spines, or parachutes
Large number of seeds
Seed Germination
• Time between seed is planted, its
development until it is self – supporting
• Begin once planted or lay dormant
– Physical or chemical reactions
– Nutrients inside seed
During Germination
• Embryo swells to burst through the seed coat
• Radicle (10 root)
– Grows downward
– Hypocotyl
• connected to cotyledons and radicle
• Arches and pushes up through soil
– Arch emerges the hypocotyl straightens
– Cotyledons and epicotyl are pulled out of the soil
• Primary leaves unfold and stem elongates
• Primary leaves/true leaves completely emerge
– Cotyledons fall off
– Photosynthesis begins
Improving Chances of Germination
• Seeds are primed or enhanced
– Stimulate growth hormones in various solutions
– Loam, pH, nutrients, and drainage
– Scarification
– Soaking seeds prior to planting
Plant Growth
• Regulated by hormones
– Stimulate or restrict growth
– Auxins, gibberellins, cytokinins, inhibitors
Plant Hormones
• Auxins
– Accelerates the growth in stem and leaf
• Gibberellins
– Stimulate growth in stem and leaf
• Cytokinins
– Stimulates cell division works with auxins
• Inhibitors prevent germination or stem growth
– Stimulate fruit ripening by emitting ethylene gas
Other factors
• Apical dominance
– Terminal bud secretes hormones
– Inhibit lateral buds on same shoot
– Once plant reaches flowering stage bud becomes
flower
Rooting Hormones
• Cuttings
• Root – promoting hormones
– Indoleacetic acid (IAA), natural
– Other forms of this rooting compound used
commercially