BIO306 Exam 1 with flashcards
Lecture One: Introduction and History
Why are plants important?
Plants provide food, fuel, and fiber for humans.
All caloric intake comes from plants, sustaining all life on Earth.
Plants provide air and water purification and habitats. They prevent erosion, provide pharmaceuticals, and give beauty to spaces.
Plant Processes
Photosynthesis
Plants undergo photosynthesis, converting carbon dioxide and water in the presence of sunlight into oxygen and sugars.
The source of photosynthesis is leaves, and the sink is fruit.
Seed Germination
Seeds go through three stages for germination:
- Uptake of water
- Formation of enzyme systems
- Metabolism of storage products
For a seed to germinate, three requirements must be met:
- The seed is viable
- Environmental conditions are favorable
- Dormancy is overcome
Plant Responses
Plants react to their environments in many ways
Phototropism..movement in response to light
Thigmotropism..movement in response to touch
Gravitropism..movement in response to gravity
Dormancy
Dormancy..the temporary suspension of visible plant growth
Quiescence..dormancy due to lack of necessary external environmental factors
Rest..dormancy due to internal limitations
Dormancy can be positive and negative in crop production.
- Dormancy is good because wheat grains can lay Dormant in storage
- Dormancy is bad because weeds can lay dormant in fields for years
Senescence
Senescence..a failure of plant reactions preceding cell death
By delaying senescence we can allow crops to grow and produce longer, as well as allowing flowers and fruits to last longer
What is Horticulture?
Without horticulture there would be a very different landscape in regards to the plants around us and the foods available to us.
Agriculture..production of plants and animals to meet basic needs of the human population
Forestry..planting, managing, or caring for forests
The word “horticulture” comes from hortus cultura meaning garden cultivation
Horticulture differs from agriculture or forestry in that there is more intensive management where the individual plant is important and there is a higher gross return per unit area per time.
Horticulture..the cultivation of a crop that is highly valued and intensely managed where the individual plant matters
History of Horticulture
Cultivation of edible plants began 7,000 to 10,000 years ago.
Agriculture lead to an available and dependable food supply, which in turn lead humans to be able to become scientists, artists, and engineers. All quality of life increased.
Around 3,000 B.C.E. preparation, irrigation, and pruning of plants took place in Egypt. Irrigation lead to the ability to create extensive and planned gardens
Irrigation spread through Mesopotamia, Babylonia, and Assyria and by 1800 B.C.E. 10,000 square miles were under cultivation to feed 15 million people.
Greek philosophers contributed to the study of crops, such as Theophrastus, who is considered the father of botany.
Romans made no major horticultural advancements, but they did use and improve on the technology of conquered peoples. This included grafting, budding, legume rotation, storage of fruits and vegetables, and the creation of the first greenhouse-like structure.
Arabian cultures established botanical gardens between 800 and 1300 C.E.
Monks perpetuated science through the Middle Ages and the Renaissance period brought forth new scientific discoveries.
There are many ideas regarding how humans developed agriculture, including various cultures believing it to be a divine gift.
Early societies grew figs, dates, grapes, and olives as well as roses, ornamentals, and medicinal plants.
The Chinese developed cultural practices for tea, oranges, and Ephedra.
In the Americas, Pre-Incans in Peru cultivated corn, potatoes, cacao, tomatoes, peppers, and beans about 5,000 years ago.
Norman Borlaug
Borlaug lived from 1914 to 2009 and fathered the Green Revolution
Borlaug is credited with prevented the starvation of one billion people by developing disease resistant wheat varieties for tropical nations
Green Revolution
The Green Revolution occurred from the 1940s to the 1970s when populaitons were rising and crop yeilds were stagnating
The Green Revolution arose out of necessity and resulted in the modernization of agriculture, leading to enhanced crop yields, increased food security, and reduced hunger.
Timeline
- 8000 B.C.E..domestication occurs
- 3500 B.C.E..Egyptians begin using irrigation
- 1492..European discovery of the New World
- 1800..Chemical fertilizers first used
- 1862..US Merrill Land Grant College Act establishes agricultural institutions and the USDA is introduced
- 1866..Mendel describes inheritance
- 1887..The Hatch Act established an agricultural experiment station in each state
- 1930..the first plant patent is given
- 1970..Normal Borlaug fathers the Green Revolution
- 1982..the first GMO crop is created
Recent Advancements
New cultivars are continuously improving crop quality and yield as well as pest and environmental resistance.
Created understanding of plant-water relationships helps improve the efficiency of irrigation systems.
Light can be used to trigger or delay flowering.
Temperature control increases production efficiency of greenhouses.
Plant nutrition improves through fertilizers delivered in specific ways at specific rates.
Rhizosphere soil-free mixes
Integrated pest management is more environmentally friendly.
Plant growth regulators can be applied to control height, branching, flowering, and fruit size
Horticultural engineering can automate processes and implement remote sensing.
Post-harvest refrigeration and controlled atmosphere extends the viability of food.
Lecture 2: Careers and Classification
Diversity of the Horticulture Industry
There are numerous ways that one can find a career in horticulture:
- Creating and distributing supplies such as pots, chemicals, tractors, and processing equipment
- Grower services including pest control, nutrient analysis, and greenhouse maintenance
- Production of crops includes skilled and unskilled labor, GMO creation, and tissue culturing
- Marketing of crops is crucial, as producing a crop is useless if there is no market for it
Horticulture in the U.S.
In 1862 the Morrill Act was signed and the USDA was created, causing a boom in horticultural research
The Hatch Act of 1887 led to experiment stations in every state
In 1889 the US Department of Agriculture was elevated to cabinet status
Areas of Horticulture
Furthering studies in horticulture can include plant sciences, animals science, engineering, and social sciences
Horticulture is closely related to applied plant sciences and agronomy, as well as forestry.
Horticulture can be broken down into three sections:
- Ornamental horticulture
- Floriculture
- Landscaping
- Interiorscaping
- Olericulture (vegetables)
- Pomology (fruits and nuts)
Ornamental Horticulture
Ornamental horticulture..growing plants for natural beauty
Floriculture..production, transportations, and use of flowers and foliage plants
Floriculture accounts for more than half of all non-food horticulture.
Floriculture crops are primarily grown in greenhouses in temperate climates and are very time sensitive, including Easter lilies, poinsettias, and Christmas cactus.
Landscape horticulture..production, design, and marketing of landscapes
Nurseries are very important in landscape horticulture.
Interiorscaping..growing plants for inside usage, including indoor malls and medical offices
Olericulture
Olericulture..vegetable production, harvesting, storage, processing, and marketing
Olericulture is very complex and competitive.
Pomology
Pomology..growing, harvesting, storing, processing, and marketing of fruits and nuts
Post-harvest preservation is a major aspect of pomology
Examples of Careers
Many jobs are available within horticulture including:
- Florist
- Golf course superintendent
- Cooperative extension specialist
- Crop consultant
- Teaching
- Research
- Botanical gardens and arboreta
- Landscape architect
Classification of Horticultural Plants
Theophrastus was the first person to classify plants
Carolus Linnaeus was the creator of the current classification system that is now regulated by the International Code of Botanical Nomenclature
The classification system assigns organisms into kingdom, phylum, class, order, family, genus, and species (King Phillip Came Over From Germany Stoned)
Scientific names are typically preferred over common names as common names can be misleading and refer to a number of different species.
Grouping Horticultural plants
There are many different ways to group horticultural plants together
Dicots vs. monocots
- \
- \
Kinds of stems
- Stem types are described as physical hardness
- Herbaceous..stems that are not woody and are short lived
- Vines..herbaceous plants that twine
- Woody plants..dense, sturdy, long lived plants
- Liana..woody plants that twine
Climate
- Warm season and cool season are often categories used for grass and vegetables that define optimal conditions for growth and survival
- Plants can be cold hardy or tender
Soil moisture
- Hydrophytes..aquatic plants such as water lilies
- Xerophytes..drought tolerant plants such as cacti
- Mesophytes..plants that prefer intermediate soil moisture, a group including most plants
Unique characteristics
- Halophytes..plants that thrive in high salt soils
- Basophilic..plants that prefer basic soils
- Acisophilic..plants that prefer acidic soils
Life Cycle
- Annuals..plants which go from seed to seed in one season
- Biannuals..plants that have a two season life cycle
- Winter annuals..plants that germinate in the fall, overwiner, and flower in the spring
- Perennials..plants that live two or more seasons
Foliage
- Deciduous..plants that drop their leaves
- Evergreen..plants that hold leaves all year long
Usage
- Edible..plants whose primary usage is consumption
- Amenity..plants that provide aesthetic primarily
Terms
Forma..subdivision of a species differing only slightly
Variety..subclassifications of the traditional species
Plant varieties are listed as the genus and species name followed by their variety, such as Scilla sibirica var. alba.
Cultivar..a group of plants within a species often distinguished by flower, fruit, or vegetative characteristics that can be patented
Cultivars can be listed of ‘Hidcote’ or cv. Hidcote, but should be kept separate.
Hybrid plants names should be preceded by a capital X (Petunia X hybrida)
Cultigen..plant or group of plants originated in domestication with no native form
Cultigens include brussels sprouts, cabbage, and corn
Line..sexually reproduced cultivar
Clone..population of plants derived asexually from one individual
Lecture 3: The Plant Environment and Light
Plant Environment
Horticulture is the manipulation of plants and their environment
Plants are bred for particular characteristics and growth
A plant’s environment includes both abiotic and biotic factors
- Atmospheric environment includes wind, light, temperature, and rainfall
- Edaphic environment refers to underground conditions
Plants are influenced by genetics primarily and their environment secondarily. Their environment impacts growth and development.
Wind
Wind is an abiotic facor that impacts aboveground plant growth
Higher winds lead to plants that are smaller, more compact, and with a tougher cuticle.
Wind cools a plant, reduces moisture, and reduces disease by making plants more resistant to mechanical stress, pathogens, and pests
Wind can cause destruction of plants, spread spores, pests, and seeds, and cause salt spray.
Light
Light is majorly important to plant growth
Light can be defined by its itensity (quantity), color (quality), and the length of the dark period (photoperiod).
Quantity
Light quantity..the amount of light within particular wavelengths
The main source of light for plants is the sun and the highest amount of light is at noon.
Light can be absorbed or reflected off of a leaf; only a small amount is used in photosynthesis
Photon..discrete particle of energy
Light compensation point..where carbon dioxide fixed by photosynthesis is equal to that lost by respiration. At this point a plant maintains tissue but does not grow.
Light saturation point..the point where light is no longer the limiting factor. Varies by species and number of leaves per individual.
Quality
Light quality refers to its wavelength
Plants absorb light from the visible spectrum. Chlorophylls, carotenoids, and phycobilin absorb light from specific wavelength
Leaves absorb blue and red light and reflect green light.
Photosynthesis
Photosynthesis takes place in the chloroplasts.
Light reactions are driven by light energy and occur in the grana.
Photosynthesis required carbon dioxide, water, and light, and yields glucose and oxygen as a waste product.
Stomatal opening is regulate by guard cells and facilitates carbon dioxide entering the leaves as well as water exiting.
Spacing and Orientation Issues
Field plants need to be spaced ideally for maturity. This leads to wasted space when plants are young.
As a rule of thumb, bigger plants should be placed in the back or to the north and smaller plants should be in the front or to the south.
Pruning
Horticultural crops are often pruned for enhanced light interception, particularly for more light to hit the middle of the tree.
Pruning properly allows for more photosynthesis, more sugars, higher yields, and more fruit color.
Ornamental hedges are pruned for aesthetic, but also light capture. Keeping bottoms wider ensures that the tops don’t shade lower leaves.
Etiolation
Etiolation..exaggerated plant stem growth in the absence of light
Etiolatoin results in visible internode elongation and yellow tissues
Etiolation does not occur in monocots, rather leaves just get bigger
Cuttings from etiolated leaves root easier
Blanching..when plants or plant parts are covered to be devoid of light.
Cauliflower heads are covered with leaves to keep the head white in an example of blanching.
Plants can etiolate in response to blanching treatment
Phytochrome Response
An excess of red and far red light can lead to phytochrome responses in plants. This is a light quality issue.
Phytochrome resonses are essentially etiolation, but due to lower quality light rather than lower quality.
This occurs in plants so that they can outcompete surrounding competitors that may be shading them.
Anthocyanin Production
Light can stimulate anthocyanin production, making fall leaves more colorful and fruits more red.
Photoperiodism
Photoperiodism..a plant’s response to daylength where darkness is the critical portion
Day neutral plants..plants that flower across a wide range of day lengths
Some day neutral plants flower more or less in response to day length, called quantitative long or short plants.
Long day plants..plants that flower when nights do not meet a critical length
Short day plants..plants that flower when nights are more than a certain critical length
Alternating day length plants..plants that need short days followed by long days or vice versa
Understanding photoperiodism allows plants to be produced in any hemisphere at any time.
Critical night length aries by species and by cultivar of a species.
Storage organ development can also depend on photoperiodism, such as in onion and garlic, which depend on a long day (short night)
Plants can be very sensitive to light when it comes to photoperiodism, with some being able to be reset by a flashlight.
Shade Tolerance
Many horticultural crops need full sun
Rapidly shifting an individual from shade to sun or vice versa can cause issues with scorching and mortality
Supplemental Lighting
A variety of supplemental lighting can be used to improve plant growth
High intensity discharge lamps are very expensive, but can last up to 24,000 hours, be used in windowless warehouses, and increased rose production by 240%
Fluorescent lamps are used in seed germination and tissue culture. They are less intense but can be used to lengthen the day
Incandescent lamps are too hot and have improper wavelengths, so they are primarily used to control the photoperiod
LED lights are expensive, but last longer, use less energy are harder to break, and can be put closer to plants than other light options.
Lecture 4: Temperature
Temperature is the most important factor in plant distribution. It also plays a major role in plant physiology, impacting growth, development, flowering, dormancy, yield, and color.
Hardy plants are less sensitive to temperature.
Tender plants cannot tolerate cold temperatures.
Classification
Many horticultural crops are divided into cool season, intermediated season, and warm season.
Most plants can survive from 0 to 50 degrees celsius, but 10 to 30 degrees celsius is optimal.
The USDA breaks the country into zones 1-11 based on annual minimum temperatures. Zones do not factor in maximum or mean temperatures.
Plants can be grown outside of their zones by using protection, placing them in sheltered areas, and burying them with soil and snow.
Soil Temperature
Soil temperature impacts seed germination, root growth, water uptake, and disease.
Plant roots stop growing when soil temperature is below 41 degrees Fahrenheit.
Sandy soils warm more quickly than clay soils due to differences in water content. Soil temperature is also impacted by air temperature, wind, and solar radiation.
Optimum soil temperature is 59-86 degreed Fahrenheit
Modifying Soil Temperature
Soil temperature can be modified by applying plastic mulch in light or dark colors to achieve the desired effect, altering soil moisture, heating irrigation water, or using heating pads.
Thermoperiodicity
Thermoperiodicity..When plants grow better with alternating day and night temperatures
In 1944 it was discovered that tomatoes grow much less when they are constantly at 80 degrees Fahrenheit than when the day was 80 degrees Fahrenheit and the night was 68 degrees Fahrenheit.
Thermoperiodicity is especially important to plant height
Recommendations regarding thermoperiodicity vary based on species, market, and sunny vs. cloudy.
Lilies, poinsettias, and chrysanthemums grow taller if night temperatures are constant and day temperatures are increased, but shorter if the night is increased and the day is constant.
The difference between night and day is DIFF, calculated by subtracting the night temperature from the day temperature.
Growing Degree Days
Growing degree days relate to development and reproduction of plants and insects. They are also known as heat units.
Growing degree days are used for organisms that cannot maintain their own temperature, where their development is predicted by temperature and time.
Growing degree days help people know when to scout for pests or market crops.
Minimum development threshold..minimum temperature at which growth occurs
Maximum development threshold..maximum temperature at which growth occurs
A growing degree day is 24 hours at 1 degree above the minimum development threshold
Biofix date..date at which you being calculations, including seedling emergency, calendar date, first trapping, etc.
Degree days= ((daily maximum temperature + daily minimum \n temperature)/2)-minimum threshold temperature
A plant needs a certain number of degree days to exist.
Dormancy
Buds of woody plants go to pre-dormancy in the summer, which is broken if the plant needs more growth. By winter the buds are dormant. If a plant is placed in a greenhouse after this, buds will not grow unless overcome by a chilling period.
There is a minimum number of hours that a temperature must be below a certain threshold for buds to break dormancy.
Chilling period varies by species and cultivar.
Endodormancy..imposed by internal blocks in seeds and buds, regulated by hormones and removed by winter chilling (rest)
Ectodormancy..plants refrain from growing until external conditions are satisfied (quiescence)
Both endodormancy and ectodormancy work together to prevent bud break during the wrong time of year.
We can overcome dormancy by calculating chilling hours and the heat units required for buds to break once chilling hours are reached.
Temperature Injury
Chilling Injury
Chilling injury can occur to tropical plants at temperatures as warm at 59 degrees Fahrenheit (non-freezing temperatures).
While tropical plants are susceptible to cold at any time, temperate plants have different tolerances depending on whether they are growing or dormant.
Two main freeze events can threaten plants that grow in temperate regions.
Advective freeze..mass of cold air moved in by strong winds often leading to temperatures below freezing for a full day or more.
It is difficult to protect plants from advective freezes as they are very windy and have long durations.
Radiational cooling..clear nights and calm winds that last a few hours.
Protection
There are multiple ways to protect from radiational cold events as they typically only last a few hours on either side of the sunrise.
Row covers..protection from radiational cooling that can offer 1-3 degrees C of protection. Woven materials protect more than paper or plastic
Torches..a method of protection from cooling events that uses open flames throughout plantings, used widely in European vineyards
Helicopters..can be used to protect crops from cooling by mixing the air
Irrigation may be used to protect plants. Overhead irrigation begins at a very specific time using low volume sprinklers. As the water freezes, it gives off heat that warms plant tissues. Irrigation must continue until the ice is melted. This method is only effective for short periods within a few degrees of freezing.
Other Forms of Winter Injury
Sunscald..damage of thin barked trees which occurs when temperatures are below freezing, sun hits the bark and raises the temperature, thawing the tissues, and freezing conditions return as soon as the sun is no longer on the tissues. The cells die and the bark splits.
Frost cracking..splitting of turns due to extremely cold temperatures
Summer Injury
Very high temperatures can kill plants
High head with direct sunlight can cause sunburn or sunscald.
Temperature Fluctuation Injury
Rapid changes in temperature can cause injury to plants, sometimes even including cold water falling on leaves.
Site Selection
Temperatures are important to consider when selecting a site, with many factors impacting it such as air, slope, altitude, bodies of water, and latitude.
Frost pockets..low areas where cold air settles
Cool air is more dense than warm air and thus will flow downhill. Fruit orchards are usually planted on slopes to avoid cool air.
Altitude..the elevation of the site
For every 300m increase in altitude, the air temperature can drop by 5 degrees celsius, and higher altitudes have higher thermoperiodicity.
Variables at particular latitudes make prime locations for fruit production.
Large bodies of water can be useful for crop production due to the temperature moderation provided by the heat capacity. Warm water in the fall protects from early frosts, cool water in spring prevents buds bursting before a cold snap, and summer and winter temperatures are much less extreme.
Lecture 5: Water
70% of the Earth’s surface is water and many ancient civilizations were built near water.
Water is important for plants so that they can perform photosynthesis. Requirements vary by crop, region, and development state. Herbaceous plants are 80-90% water by weight, woody plants are 50% water by weight, and tomatoes are 95% water.
200 to 1000 grams of water can be needed to produce 1 gram of dry matter.
Water has unique properties that make it even more useful for plants.
- High specific heat stabilizes extreme temperatures
- Water is a universal solvent, helping transport nutrients, fertilizers, sugars, and hormones
- Surface tension
- Turgor pressure keeps plants erect
- Water in guard cells open stomata
Water in Air
Transpiration..loss of water from a plant as vapor. Loss occurs through stomatal openings
Evapotranspiration..evaporation loss of water from plants and soil influenced by humidity
Water in Soil
When soil is saturated, all pores are full of water moving along gravitational potential
When soil is not saturated, water moves by metric potential
Water enters plants through root tips.
Field capacity..when water is only held in small pores, reached when large pores are drained by gravity
Permanent wilting point..the point when water will not longer be able to be absorbed
Incipient wilting..occurs when plants temporarily wilt and then recover without additional water
Irrigation
Water penetration of soil is important in irrigation as runoff is not desired and standing water reduces oxygen to plants
Irrigation..supplemental meeting of water needs of a crop
There are many different ways to irrigate plants
- Hand watering is simple and low cost, but has variable success and requires a lot of labor.
- Furrow irrigation..irrigation where ditches are placed between crop rows and gates are open to release water
- Requires ground to have slope, not suitable for well draining soils, and does not wet foliage
- Flood irrigation..irrigation that covers most of a field
- Most inefficient form of irrigation
- High volume irrigation
- Overhead irrigation using sprinklers
- Circular pivot sprays in a circular pattern
- Lateral system walks through a field
- Common in fields as good airflow is needed if it is used in a greenhouse
- Wind can distort patterns
- Evaporation loss is high, equipment is expensive, and salt can build up in soils
- Low volume irrigation
- Trickle or drip systems
- Conserves water, limits weeds, reduces disease issues, more uniform, and fertilizers can be added
- Clogging can be problematic, coyotes may destroy systems, and they are expensive
- Subirrigation..applying water below the root zone
- Floor flood
- Plants are on a floor or bench and flooded for 15 minutes at a time
- Efficient for water and fertilizer, low labor and cost
- Pathogens become problematic very quickly
Open irrigation system..water is not reused
Closed irrigation system..water is recycled repeatedly
Lecture 6: Nursery and Floriculture
Nursery Crops
Nursery crops mostly involve the sale of woody ornamental plants in one of the fastest growing segments of agriculture
In the USA there are both wholesale and retail nurseries
Wholesale nurseries have fewer crops on a larger scale and sell to other nurseries whereas retail nurseries often sell these plants.
Product mix..type of plants to be grown
Methods of Nursery Production
Container production and field production are used, but the trend is leaning towards container stock.
- Less labor required
- More control
- High density of crop
- Quicker recovery
- More marketable
Container Nursery Production
Plants are grown in pots
- Very valuable in the market
- Pots need to last a long time
- Ground needs to be level
- Issues with root binding
- Pots are expensive
- Roots are not are protected in the winter
- Plants should be grouped together or border pots can be placed
- Alternatively, pots can be buried in the ground
Field Nursery Production
Fields need tilled before planting
- Cover crops may be used to make soil more fertile
- Plants must be spaced for maximum size because they cannot be moved
- Space for equipment must be considered as well
- Plants may be sold “balled and burlapped” with a ball of soil dug up and wrapped or bare root, which risks transplant shock
Nursery Stock Protection
Greenhouses may be used to control the environment
- Cold frames have no heat
- Shadehouses only protect from the elements
Floriculture
The first use of flowers is documented in 2800 B.C.E. Egypt
Flower petals are used during ceremonies in Greece in 600 B.C.E.
Flowers are used in India, China, and Japan for religious ceremonies
In the 1920s corsages began to be used
Cut Flowers
Flowers are detached and used in arrangements
Cut flowers have very short lifespans
Both woody and herbaceous plants are used
Vase life..how long a cut flower will last
There are different stages or development that are optimal for harvesting in different plants and all species have their own vase life
Once cut one should minimize a flower’s exposure to heat and ethylene and should recut stems and place in warm, high quality water
Interiorscaping
Interiorscaping..ornamental plants for functional and aesthetic purposes
Interior plants filter the air, reduce noise, and look nice.
Lighting is key in interiorscaping.