Horticulture
Science and art of cultivation fruits, vegetables. and ornamental plants
How is horticulture in your everyday life?
Can effect the food you eat and where you live
Varied aspects of horticulture?
Fruits, vegetables, ornamental plants
Common ways to group plants
Life cycle, growth habit, environmental adaptation, end use or function
Scientific protocols used to name plants
Genus + spientific eithet = species
Photosynthesis reaction
6 CO2 + 6 H2O = C6H12O6 +6 O2
Light Reaction
converts light energy into chemical energy, dependent on light
Light Reaction process
Leaves collect light through chloroplasts, energy in light used to generate oxygen from water and energy in chemical compounds
Calvin Cycle
Chemical energy captured in the light reaction to "fix" carbon dioxide in the atmosphere into organic compounds
Light required for Calvin Cycle?
No
Importance of the Calvin Cycle
removed 200 billion tons of CO2 from the atmosphere every year.
Respiration
CO2 increases while O2 decreases, reverse of photosynthesis and happens in the dark
Carbon Gain
Photosynthesis - Respiration
Source
Suppliers of carbon- primary leaves
Sink
Users of carbon- flowers, fruits, roots
Photosynthate
Fixed carbon must be transported to the sinks
Basic plant structures
Leaves, stem, roots, flowers
What is the function of leaves?
Harvest solar energy
What is the function of roots?
Acquire water and essential minerals, anchorage to soil, food storage
What is the function of flowers?
reproduction
What is the function of stems?
support and vascular system
Why learn names of structures and functions?
Plant identification, how plants grow, connection between form and function
Epidermis
outside varied cells
Stoma and Guard cells
Epidermis
Mesophyll
Palisade contains chloroplasts and spongy
Vascular system
carries water and minerals to and from different area, xylem and phloem
Xylem
water and minerals from root to leaf
Phloem
Carbon from leaf to rest of plant
Sclerenchyma
fibers for structural strength
Modifications of leaves
Scales of bulbs serve as storage tissue, tendrils modification so plant can vine, sines or thornes
Structures of stems
apical meristem, stem, node, internode
Stem modifications
spurs-support flower and fruit in tree fruit
stolons- grow horizontally along ground, useful for propagation
Meristem
Actively dividing undifferentiated cells, source of new cells
Structures of roots
root cap, root hair region, apical meristem, elongation zone, maturation zone
Modifications of roots
carrot or sweet potato that serve as storage tissue, other modifications are for support
Cell division
source of new cells for growth of an organ or tissue
Expansion or elongation
increase volume of cell, area just behind apical meristem
Differentiation
development of specialized cells, behind meristem
Applied science
Applied science is a discipline of science that applies existing scientific knowledge to develop more practical applications, like technology or inventions.
Ornamentals
Floriculture - production of flowers and flowering plants
Landscape Horticulture - aesthetic / functional use of plants in the landscape
Scientific method
a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.
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Observation of a phenomenon.
Formulation of an hypothesis to explain the phenomenon (cause/effect).
Hypothesis is used to predict additional observations.
Performance of experiments to test the predictions based on the hypothesis.
Specialty areas of horticulture
Food
Pomology - production of fruits
Olericulture - production of vegetables
Functional and practical groupings
likeness" or "sameness"
Ultimate: identical individuals, twins.
Over history, grouping has been done by: visible characteristics (eye and microscope), and today, visible and molecular (DNA).
Hierarchical scientific classification system
�Basic Group
o SPECIES
�Group of species
o GENUS
�Group of genera
o FAMILY
terminology and structure of correct nomenclature
Simplicity - Short names
Universal -Accommodate many languages globally
Stability - Not change too much over time
Linnaeus' contribution
Swedish botanist, physician and zoologist, who formalized the modern system of naming organisms called binomial nomenclature. He is known by the epithet "father of modern taxonomy".
Value and limitations of different systems
Complete technical or specific name of a species includes the "authority" or author of the plant name
(Genus + specific epithet + authority)
Plant cell
Roles of ADP, NADPH, h20, CO2
Energy in light is used to produce compounds (ATP, NADPH) that capture this energy in chemical bonds.... ?
Roles of chlorophyll and other pigments, absorbed light
Chlorophyll absorbs red and blue light in the visible spectrum and green light is either transmitted or reflected.
Rubisco
the most abundant protein on earth - 20 kgs for every human.
Carbon Gain
Growth of plants depends on how much carbon is retained, or gained, by the plant. Amount of carbon gained is the difference between photosynthesis and respiration. Carbon gain = photosynthesis - respiration. Carbon gain is not constant but is influenced by light levels, stage of development and other factors.
CO2 enrichment
may be used in some controlled environments, such as growing plants in space.
Definition of Plant Growth
a small cell getting larger. One cell dividing to become many cells
cell enlargement - increase in the volume of a cell.
The combined effects of cell division and cell expansion lead to growth of plant organs and to the increase in size of a plant
Primary growth in plants
growth that leads to increased height of shoots or length of roots. Growth occurs at the apices of these organs. Cells in the apical meristems divide and provide cells for growth.
Meristems
Meristems contain actively dividing cells. Meristem cells are small, undifferentiated, have thin cell walls and small vacuoles, and are tightly packed together. Cell expansion occurs in the area just behind the apical meristem.
Secondary growth in plants
increased diameter of stems and roots. Primarily due to activity of the cambrium. Layer of meristem cells between the phloem and xylem.
Branching in stems, where?
Auxillary buds contain a meristem that is normally not active.
Phototropism
How a plant senses what direction the light is coming from. (Phototropin - blue light - protein)
Gravitropism
ROOTS GROW DOWN. The root cap contains the gravity sensor. Shoots exhibit negative gravitropism, they grow in the opposite direction to the force of gravity. SHOOTS GROW UP.
5 main plant hormones
Auxin, Gibberellins (GA), Cytokinins, Abscisic Acid (ABA), Ethylene
Auxin (Primary role in promotion or inhibition of growth and development)
Differentiation, elongation, growth responses (phototropism, gravitropism). Suppresses growth of axillary buds.
Gibberellins (GA). (Primary roles in promotion or inhibition of growth and development)
Elongation, cell division, seed germination. Control metabolism of stored reserves during seed germination.
Cytokinins (primary roles or inhibition of growth and development)
cell division, diferentiation, delays senescence of leaves.
Abscisic Acid (ABA) (primary roles in promotion or inhibition of growth and development)
responses to stress, stomatal opening (stimulates closure of stomata). Inhibits seed germination.
Ethylene (primary roles in promotion or inhibition of growth and development)
fruit ripening, flowering, flower senescence. Triggers abscission of leaves and fruits. Increases propostion of female flowers in cucurbits. Regulates shoot growth during germination.
Floral structure functions
Reproduction, allows for maintenance of genetic diversity. Ornamental value, fruit and seed production.
variations on the typical
A flower lacking any one or more parts (sepals, petals, stamens, pistils). A flower lacking one sex or the other. A flower with all parts is COMPLETE. A flower lacking some part is INCOMPLETE. A flower with both sexes is PERFECT. A flower lacking one sex is IMPERFECT. (all IMPERFECT flowers are INCOMPLETE, not all INCOMPLETE flowers are IMPERFECT.)
monoecious
both sexes on the same plant. (one house, one plant)
dioecious
only one sex on one plant (two houses, two plants)
mechanism and process of "photoperiodism" for floral induction
(((ORIGINAL VIEW: Plants have evolved mechanisms to make use of the fluctuation in daylength in the temperate regions of earth as an environmental cue for flowering. Those plants that are not photoperiodic are "day neutral." A photoperiodic plant will only flower when the length of the day is more or less than a crital length. "short day" plants flower when the day length is less than a critical length and "long day" plants flower when the day length is more than a critical length.)))
(((ACTUAL MECHAISM: "short day" plants flower when the night length is more than a critical length - thus, they are really "long night plants". "Long day" plants flower when the night length is less than a critical length, thus they are really "short night plants")))
What does night interruption help prove?
(A short period of light in the middle of the night) You can use this to change a "short day" (long night) into a "long day" (short night) (really two short nights)
What other factors can induce flowering?
light intensity. Girdling. Temperature, Juvenility.
What are the steps in pollination and fertilization, and what is happening in each one?
1. Anthesis (pollen shed) - pollen produced in great excess.
2. Pollination (pollen transfer to a stigma) - within same flower or same plant (SELF POLLINATION) - between different plants (CROSS POLLINATION)
3. Pollen germination (on stigma) - pollen grain is hydrated (moisened) on the stigmatic surface, germ tube begins to grow toward ovary.
4. Growth of germ tube to ovary.
5. Fertilization of ovule.
Fertilization
Germ tube enters embryo sac. One sperm nucleus fuses with egg to become embryo, other fuses with polar nuclei to become endosperm.