Horticultural Fruit Crop Production - Vocabulary Flashcards
Branches of Horticulture
Olericulture: Study of vegetables
Pomology: Study of fruits
Floriculture: Study of flowers (as a crop)
Spices, medicinal, aromatic crops: e.g. black pepper, mint, patchouli
Etymology and Background
Hortus: Latin for garden or enclosure
Cultura: Latin for cultivation
Importance of Fruits
Excellent source of vitamins, minerals, and fibre
High economic importance (high net profitability)
Basis for value-added products
Increasing per capita consumption
Growing health consciousness among consumers
Fruit Industry in the USA (Examples and Order of Importance)
Major fruits: Grapes, Citrus, Apples, Strawberry, Pears, Peach, Cranberry, Cherry, Prunes, Blueberry
US Agricultural productions: Citrus states contribute about 3.4 \times 10^9 \text{ USD} to the economy and employ about 6.0 \times 10^4 people
Other important fruits include: Avocado, Nectarine, Raspberry, Plum, Olive, Date, Apricot, Kiwi, Papaya, Pineapple
US States and Fruit Production (Regional Highlights)
States listed with various fruit production profiles (e.g., Washington, California, Florida, etc.)
Spatial distribution indicates diverse fruit crops across different climates
Distances and regional notes (e.g., 200 \text{ km}, 100 \text{ mi} markers) appear in slides, indicating regional scale connections
Introduction to Fruits
Fruit: The matured or ripe ovary of a flowering plant, with or without accessory parts
Fruits can be used raw or canned/processed
Parts of a Fruit
Normally fruits have two main parts:
Pericarp
Seeds
Seed description: Ovules mature into seeds; seed components include the Seed Coat, Embryo, and Stored Food
Pericarp Structure
Pericarp: The outer wall of the ovary that matures into the wall of the fruit
Pericarp can be either dry or fleshy
Layers of the pericarp:
Exocarp (outermost layer, typically the skin)
Mesocarp (middle layer, often the edible part in fleshy fruits)
Endocarp (innermost layer, surrounds the seed)
Seed Structure
Ovules mature into seeds
Seed functions: To protect and nourish the embryo; to produce new plants
Seed components: Seed Coat, Embryo, Stored Food
Classification by Climatic Region
Fruit plants thrive in three main climatic groups:
Temperate zone fruit plants
Subtropical zone fruit plants
Tropical zone fruit plants
Temperate Zone Fruit Plants
Enter dormancy in fall/late summer
Require specific chill hours to break dormancy and resume growth in spring
Tolerant to frost
Examples: apple, pear, peach, cherries
Subtropical Zone Fruit Plants
Temperature requirements are milder than temperate crops
Moderately tolerant to chilling (brief spells)
Chilling can sometimes aid production
Sensitive to frost
No definite dormancy period or chill hour requirement
Examples: avocado, citrus, olives
Tropical Zone Fruit Plants
Require high temperatures; not tolerant to freezing
Perform well in hot, humid weather
Narrow diurnal temperature variation (small difference between day and night temperatures)
Examples: mango, jackfruit
Classification by Ripening Behavior
Fruits are classified by their ripening behavior into two groups:
Climacteric fruits
Non-climacteric fruits
Climacteric Fruits
Continue ripening after harvest; often harvested at a fully mature but unripened stage
Post-harvest ripening makes fruits soft and delicate, so transport mainly occurs at the mature stage
After harvest, they emit higher levels of ethylene and show an increased respiration rate, accelerating ripening
Ethylene gas is sometimes used to induce or enhance ripening in closed environments
Examples: mango, banana, papaya, pear, apple
Non-Climacteric Fruits
Do not ripen significantly after harvest
Produce very little ethylene gas
Do not respond to ethylene treatments for ripening
Show no significant increase in respiration rate after harvest
Examples: citrus, strawberry, cherries
Climacteric vs Non-Climacteric Respiration Pattern
Climacteric: The CO_2 production pattern shows a pre-climacteric minimum, followed by a climacteric peak, and then a post-climacteric decline
Non-climacteric: No such pronounced peak in CO2 production; relatively stable CO2 levels throughout
Classification by Photoperiodism
Photoperiodism: The developmental response of plants to the relative lengths of light and dark periods
Photoperiod examples (light/dark): 14 \text{ hrs} light, 10 \text{ hrs} dark
Plant types based on photoperiodism:
Short-day plants
Long-day plants
Day-neutral plants
Short-Day Plants
Also known as long-night plants
Flower when day length is less than approximately 12 \text{ hours}
Examples: strawberry, pineapple
Long-Day Plants
Also known as short-night plants
Flower when day length is longer than approximately 12 \text{ hours}
Examples: banana, apple (flowers when day length > 12\text{–}14 \text{ hours})
Day-Neutral Plants
Do not require a definite light/dark period to flower
Flower after a certain period of vegetative growth and development
Example: papaya
Classification by Morphology (Ovary Position)
Ovaries positioned on the thalamus classify fruits into three types:
Superior ovary
Half-inferior ovary
Inferior ovary
Superior Ovary
The ovary is at the highest position on the thalamus (receptacle)
Petals, calyx, and stamens are located below or around the base of the ovary
Examples: citrus, mustard (Brassica)
Half-Inferior Ovary
The thalamus forms a cup-like shape around the ovary, enclosing it partially
Petals, calyx, and stamens are attached along the rim of this cup
Examples: rose, prunus
Inferior Ovary
The thalamus tissue completely covers the ovary and is fused with its wall
Petals, calyx, and stamens are located near the top of the ovary
Examples: cucurbits, apple
Carpels (Gynoecium)
Female reproductive part of a flower, consisting of the stigma, style, and ovary
Flowers can have a single carpel (monocarpellary) or multiple carpels (multicarpellary)
Compound or Multicarpellary Gynoecium
More than one carpel in a flower
Types:
Apocarpous: Carpels are separate and distinct (isolated gynoecia)
Syncarpous: Carpels are fused together to form a single gynoecium
Locule (Locules)
Chambers or compartments within the ovary
Fruits can be unilocular (single locule) or multilocular (multiple locules)
Ovules (which later mature into seeds) are located within these locules
Classification of Fruits Based on Ovary Involvement in Fruit Formation
Three main groups based on the number of ovaries involved in fruit formation:
A. Simple fruit
B. Aggregate fruit
C. Multiple or composite fruit
A. Simple Fruit
Derived from a single ovary of a single flower
Based on pericarp maturity, these are divided into two broad groups:
I. Fleshy fruits
II. Dry fruits
Examples across various subtypes are provided in the following sections
I. Fleshy Fruits
Pericarp becomes fleshy and succulent at maturity
Pericarp layers: Epicarp (exocarp), Mesocarp, Endocarp
Fleshy fruits are further classified into:
Berries
Drupes
Pomes
Hesperidium
Pepo
1) Berries
Developed from a single flower with one or more carpels
Characterized by a fleshy pericarp and multiple seeds; the exocarp is thin, and the mesocarp and endocarp are undifferentiated (fleshy pulp)
Seeds are embedded directly in the pulp
Examples: tomato, grape, blueberry
Note: Botanically, strawberries, raspberries, and blackberries are not considered true berries
2) Drupes (Stone Fruits)
Developed from a single flower with a superior ovary and typically a single carpel with 1 or 2 seeds
Exocarp is thin; mesocarp is fleshy and pulpy (can be fibrous in coconut or tough/edible in almond)
Endocarp is hard and stone-like, enclosing the seed(s)
Examples: peach, plum, cherry, apricot, mango, almond
3) Pome
Developed from a compound, syncarpous, inferior ovary
Accessory tissue (like the receptacle) becomes fleshy along with the ovary; therefore, it is not considered a true fruit botanically, as the main fleshy part is formed from accessory tissue
The central part of the fruit contains the true fruit (ovary wall); the fleshy part is the exocarp and mesocarp; the endocarp is cartilaginous or stony, enclosing the seeds
Examples: apple, pear, quince
Accessory Fruit
Other flower parts, along with the ovary wall, form a significant portion of the fruit
Example: strawberry (the fleshy part is the receptacle, not the ovary wall), cashew apple, figs
4) Hesperidium
Developed from a multilocular, syncarpous, and superior ovary
Exocarp is leathery with characteristic volatile oil glands; the exocarp + mesocarp form the rind or cover; internal sections represent individual carpels
Inner sections contain juice vesicles (sacs)
Examples: orange, lemon, grapefruit (all citrus fruits)
5) Pepo
Developed from one carpel or fused carpels of an inferior ovary
Exocarp is typically woody or leathery; mesocarp is fleshy; contains many seeds
Examples: zucchini, cucumber, squash
II. Dry Fruits
Pericarp becomes hard/brittle with very low moisture content at maturity
Pericarp is not differentiated into distinct exocarp, mesocarp, and endocarp layers
Categorized into two types: Dehiscent and Indehiscent
Dry Fruit Types
Dehiscent: Pericarp opens at maturity along sutures to release seeds
Examples: legumes (bean, pea), brassica (mustard)
Indehiscent: Pericarp does not split open at maturity to release seeds
Examples: nuts (chestnut, hazelnut)
B. Aggregate Fruit
Develop from multiple separate ovaries of a single flower (apocarpous type)
Each ovary forms a small fruitlet (e.g., a small berry or drupe) which then matures into a cluster of seeds
Examples: raspberry, blackberry, strawberry (botanically an aggregate of achenes on an accessory receptacle)
C. Multiple Fruit
Develop from an entire inflorescence (a cluster of flowers) where multiple flowers are tightly packed
Each flower in the cluster forms a small fruitlet, and these fruitlets mature together into a single, cohesive fleshy mass
Examples: pineapple, mulberry, fig, jackfruit
Plant Propagation
Propagation: The process of developing or creating new plants from existing ones
Involves the multiplication of a plant or cultivar
Propagation ensures the continuation of a species
Structures Needed for Successful Propagation
Mist chambers: Provide mist irrigation to maintain 95\%\,\text{ to } 98\% humidity, crucial for rooting
Greenhouses: Controlled environments; specialized types include heated greenhouses and ventilated systems for air circulation
Shade houses: Provide protection against excessive sun and high light intensity
Seedling trays: Used for germination and early growth; offer space-saving benefits and ease of management
Types of Propagation
Propagation is primarily of two main types:
1) Asexual propagation
2) Sexual propagation
1) Asexual Propagation
Involves the use of vegetative parts of a plant (stem, root, leaves, or tissue culture)
Regeneration of new plants using somatic (non-sexual) tissue
Includes any vegetative part other than seeds
Advantages of Asexual Propagation
Useful for plants that do not produce viable seeds (e.g., rose, grapes, fig, seedless banana, seedless watermelon)
Produces genetically identical plants (clones), thus avoiding genetic variation common in seed propagation of heterozygous plants
Bypasses issues with poor seed germination or seed dormancy (e.g., pear, olive)
Addresses problems with seeds that lose viability quickly or are difficult to store (e.g., mango)
Grafting/budding can impart stress resistance (via rootstock); allows for quicker fruiting (e.g., grafted mangoes fruit in 3\text{–}4 years vs. 8\text{–}10 years from seed)
Disadvantages of Asexual Propagation
Often more expensive than seed propagation
Typically results in less hardy plants due to the absence of a taproot system from a seedling
Longevity may be less than seed-propagated counterparts
Limited ability to develop new varieties through genetic recombination
Less genetic variation, making the population potentially more susceptible to widespread disease or pests
Plant Hormones (Growth Regulators) in Asexual Propagation
Organic compounds that regulate rooting and shooting processes in plant propagation
Used at very low concentrations (parts per million, ppm)
Auxin is the most popular regulator for promoting rooting
Applied during early morning or late evening for spraying to minimize evaporation and maximize absorption
Application Methods for Growth Regulators
Basal quick dip method
Diluted soak method
Foliar spray method
Talc method
Basal Quick Dip / Soak Method
The basal end of the cutting is soaked in a hormone solution for 1\text{–}5 seconds (quick dip) or 2\text{–}48 hours (diluted soak)
Advantages: High success rate, quick application (quick dip)
Disadvantages: Requires longer time and space (soak), requires skill for consistent application
Spray Method
After placing cuttings in growing media, growth regulators are sprayed to moisten the soil and cuttings
Advantages: Quick application over many cuttings
Disadvantages: Requires skill to ensure even distribution and proper dosage
Lanolin Paste Method
Powdered hormones are mixed into viscous lanolin to form a paste
This method facilitates slow and sustained release of auxin to the cutting
Talc Method
Powdered growth regulators are applied by dipping the basal end of the cutting in water before coating it with the powder
Advantages: Can be stored normally; no solubilization needed; generally less expensive
Disadvantages: Potential loss of chemical during insertion into media; may lead to uneven distribution on the cutting
Techniques of Asexual Propagation
A. Cutting
B. Grafting
C. Budding
D. Layering
E. Specialized structures
F. Apomixis
G. Separation and division
A. Cutting
One of the most common methods of asexual propagation
Suitable for both herbaceous (non-woody) and woody plants
Steps: Select a healthy, disease-free shoot; use sterile, disease-free rooting media; disinfect cutting tools (e.g., with rubbing alcohol or a 1:9 bleach/water solution)
Useful links to example videos provided in source
Advantages of Cutting
Simple and fast to prepare
Requires no specialized skills for basic forms
Relatively low cost
Disadvantages of Cutting
Cuttings are fragile in early stages
Requires specific environmental conditions, often high humidity
Not all plant species root easily from cuttings
Can take longer for roots to develop compared to other methods
Types of Cuttings
A. Stem cutting
B. Leaf cutting
C. Root cutting
A. Stem Cuttings
A segment is cut from the main stem or a part of it
High-sugar shoots tend to root better
Herbaceous cuttings root best during spring (period of active growth)
Cuttings from young shoots or rooting from young plants generally have higher success rates
Types by season/maturity of wood:
i) Hardwood cutting
ii) Semi-hardwood cutting
iii) Softwood cutting
i) Hardwood Cutting
Mature, woody stems are used (typically pencil-thick); usually taken during the dormancy period
The top cut is slanted to prevent water accumulation
The basal part is often treated with rooting hormones (e.g., Indole-3-butyric acid, IBA)
Examples: grapes, fig, pomegranate, mulberry
ii) Semi-Hardwood Cutting
Slightly mature, woody, yet succulent shoots from the current season's growth
Examples: grape, fig, mango, citrus, olive
iii) Softwood Cutting
Soft, succulent, non-woody shoots; generally root more easily and quickly than hardwood cuttings
B. Leaf Cutting
Used for plants with thick, succulent leaves; entire leaves (with or without a petiole) are used to generate new plants
C. Root Cutting
Used for plants that naturally produce root suckers; best performed during dormancy when stored carbohydrates in the roots are high
Examples: blackberry, raspberry
B. Grafting
Grafting: The horticultural technique of joining or combining two independent plants to grow as a single plant
The upper portion (scion) is the desired variety providing the shoot system; the lower part (rootstock) develops the root system
Importance of Grafting
Essential for plants not easily propagated by cuttings or seeds
Enables changing existing varieties or introducing disease/pest resistance via specific rootstocks
Dwarfing rootstocks allow for higher-density planting in orchards
Can add pollinator scions to predominantly female plants to ensure fruit production
Useful for plant repair after physical, disease, or animal damage
Types of Grafting
a) Tongue grafting
b) Whip grafting
c) Cleft grafting
d) Wedge grafting
a) Tongue Grafting
Highly successful due to strong vascular/cambial alignment
Preparation: Stock prepared with a downward cut (2.5\text{–}6 \text{ cm} long); a second cut is made from the top, about one-third distance down, forming a 'tongue'
Scion: Prepared with a matching upward cut and tongue
Joining: The tongues interlock neatly
Securing: Graft is secured with waxed paper or grafting tape; the top of the rootstock is cut after successful union to allow scion bud growth
Examples: apples, kiwi
b) Whip Grafting
Similar to tongue grafting but typically involves a single slanting cut on both the scion and rootstock, without the second interlocking cut
If the scion is smaller in diameter than the rootstock, it is placed to one side to align cambial layers
Examples: apple, pear
c) Cleft Grafting
Can be performed during the dormant season; best in early spring just before active growth begins
Used to introduce new varieties or repair damaged large limbs/plants
Typically used with larger diameter rootstock (split) and smaller scions (wedge-shaped)
Examples: walnut, hazelnut, grape
d) Wedge Grafting
Best performed in late winter or early spring
The base of the scion is cut into a wedge shape; a corresponding vertical cut is made into the beheaded rootstock
The scion wedge is inserted into the rootstock opening; the union is then taped and waxed
Examples: tropical fruits like avocado, passion fruit
Grafting as Top-Working
Used to change an existing mature cultivar to a new cultivar by grafting onto established framework branches
Used to repair damaged scaffolds (main branches) due to physical injury, disease, or animal damage
Techniques include: inarching, bridge grafting, bark grafting, veneer grafting, and cleft grafting
Graft Incompatibility
Occurs when a successful union fails to form after grafting or budding
Reasons: Poor grafting technique, genetic incompatibility between scion and rootstock, disease interference, or extreme weather conditions
Signs of Graft Incompatibility
Poor plant growth, yellowing leaves (chlorosis), bulging or swelling at the graft joint, breakage at the graft joint, or eventual plant death
C. Budding
Budding is a specific form of grafting where a single bud (with a small piece of bark and cambium) is used as the scion, rather than a shoot with multiple buds
The rootstock is the plant receiving the bud
Budding can be considered grafting of a single bud
Importance of Budding
Requires smaller scion material compared to traditional grafting
Generally simpler and faster than many grafting methods
Not suitable for plants that exude excessive gums or sap from injuries
Typically forms a stronger union than some grafting types due to minimal tissue disruption
Types of Budding
a) T-budding or Shield budding
b) Inverted T-budding
c) Patch budding
d) I-budding
e) Ring budding
f) Chip budding
a) Shield (T) Budding
The scion bud must be fully mature
The scion bud is cut in a shield shape (including a small piece of bark and phloem)
The rootstock must be actively growing (bark 'slipping' easily); a T-cut is made in its bark
The bark flap is opened, the bud is inserted, and the joint is wrapped with budding tape
After successful budding, the top of the rootstock is cut above the bud to promote the bud's growth
Examples: peaches, citrus, apple, plum
b) Inverted T-Budding
Common in high rainfall regions to prevent water accumulation near the bud
Similar to T-budding, but the horizontal cut of the 'T' is placed at the bottom instead of the top, allowing water to drain
c) Patch Budding
A rectangular or square bud patch is removed from the scion; this patch size must exactly match a prepared bark area on the rootstock
Both the scion (budwood) and rootstock must be in active growth (bark slipping)
The bud patch is inserted into the prepared rootstock and secured
Examples: thick-bark trees like walnut, pecan
d) I-Budding
An I-shaped cut is made in the rootstock bark
A patch containing a bud from the bud stick is placed into the rootstock, ensuring matching thickness and cambial alignment
e) Ring Budding
A subtype of I-budding; a ring-shaped bark section with a bud is removed from the bud stick and inserted into a precisely same-sized ring cut on the rootstock
Examples: mulberry, peach (also I-budding method)
f) Chip Budding
Used when the rootstock bark does not slip easily, typically during dormant periods or when cambial activity is low
A chip of bark and wood, including a bud, is removed from a smooth area between internodes of the rootstock
A matching chip with a bud is collected from the bud stick; it is inserted into the rootstock cut and securely tied
Example: pawpaw
D. Layering
Layering is an asexual propagation technique used particularly for hard-to-root plants
The layered stem remains attached to the parent plant while adventitious roots form
After sufficient root development, the rooted stem is separated from the parent plant for independent growth
Techniques often involve notching or ringing the stem to encourage rooting; rooting hormones may also be applied
Two main types: a) Air layering; b) Ground layering
Importance of Layering
Relatively easier method for some species; the parent plant continuously provides nutrients and water to the developing roots, aiding establishment
Reduces transplant shock for the newly rooted plant
Can be costly due to labor and materials; new plants may be shallow-rooted compared to seed-propagated plants; rootstock benefits (like disease resistance) are not available
a) Air Layering
Select a healthy live branch, typically 1\text{–}2 inches in diameter, at a mid-level position
Make two horizontal cuts 1\text{–}2 inches apart around the circumference of the branch, then a vertical cut to remove the bark strip between them
Wrap the exposed cambium with moist peat moss (rooting hormones are optional but recommended)
Cover the peat moss and wound securely with clear plastic film and tie both ends to create a moisture-retaining package
When roots are visible through the plastic, cut the branch below the rooted area and plant the new, independent plant
Examples: citrus, apple, guava, pear, pecan
b) Ground Layering
Involves burying a part of the stem in the soil to encourage rooting while still attached to the parent plant
Types of ground layering:
i) Simple layering
ii) Tip layering
iii) Trench layering
iv) Mound layering (Stool layering)
v) Serpentine/Compound layering
i) Simple Layering
Suitable for plants with relatively flexible, trailing shoots; a portion of the stem is bent to the ground and buried in soil
The buried portion roots; after rooting, the rooted part is detached from the parent plant; the exposed tip forms the new plant
Examples: purple and black raspberries, blackberries
ii) Tip Layering
Specifically for plants with trailing shoots; the tip of the current season's growth is bent and buried in the soil
Pegs or weights are used to keep the tip in place underground
Roots form at the bend (node or wounded area); the new plant is then separated and planted
Examples: purple/black raspberries, blackberries