Plant Propagation and Nursery Management

MIDLANDS STATE UNIVERSITY

FACULTY OF NATURAL RESOURCES MANAGEMENT AND AGRICULTURE: DEPARTMENT OF HORTICULTURE

HORT 203: PLANT PROPAGATION AND NURSERY MANAGEMENT

GENERAL ASPECTS OF PROPAGATION

1.1 Background

· Millions of years of human existence, man were hunters and gatherers

· Distribution of plant species was influenced by their environment (climate, soil and topography) and interactions of plant, animal and human populations

· The interactions of biological and environmental components were always in equilibrium (ecological climax)

· Deliberate propagation emerged with the objective of cultivating specific preferred plant species

· This cultivation created the concept of nursery

· Nursery is where plants are propagated to be transplanted to their permanent site either as part of the agricultural unit or to be sold to others

· However, modern day plant propagation industry is now large and complex involving not only groups that multiply for sale and distribution but also industries that

· 1. provide services

· 2. sell the products

· 3. are involved in regulation

· 4. provide consultation services

· 5. carry research

· 6. involved in training

2.0 KEY AREAS OF EXPERTISE IN PLANT PROPAGATION

1. Technical skills for manipulating plant growth (Art of propagation)

· This requires a certain level of skill, practice and experience to master e.g. grafting and budding

2. Knowledge of plant growth, development and morphology(Science of propagation)

· Includes knowledge of physical, chemical and ecological aspects of propagation environment

· Acquired by supplemental studies in botany, physics, chemistry and plant physiology

3. Understanding of plants/Knowledge of best propagation techniques

· The method selected must be related to how the plant responds

3.0 PROPAGATION

· It is the controlled perpetuation of plants with the objectives of achieving an increase in number and to preserve the essential characteristics of plants

· There are 2 basic types of propagation which are;

· - sexual propagation

· - asexual propagation

· asexual propagation is the increase of plants through ordinary cell division and differentiation

· Sexual propagation is the increase of plants through seeds formed from the union of gametes

4.0 ENVIRONMENTAL FACTORS AFFECTING PROPAGATION

· In order to enhance propagation of plants there is need to manipulate the environment of propagules (cuttings or seeds) by managing the following

Microclimatic conditions (Relative humidity, ToC, light, gases)
Edaphic factors (mineral nutrients, propagation media and water)
Biotic factors (interaction of propagules with other organisms e.g. rhizal fungi, pathogens, insect pests)

4.1 Microclimatic factors

4.1.1 Water-Humidity control

· Water management and humidity are critical for any propagation procedure

· Water management can be used in regulation of growth

· Evaporative cooling when using intermittent misting can help control the propagation house microenvironment and reduce heat load on cuttings, which also permits increase in light intensity for higher rates of photosynthesis

· The important parameters for measuring water status are leaf water potential (Yleaf)

· However, turgor pressure is physiologically more important as it tells much on the turgidity of plant cells

TEMPERATURE

· Affects propagation in several ways

· Seed dormancy is broken in some woody species by cool moist stratification conditions that allow germination to occur

· In grafting heating devices are sometimes placed at the grafting union area to speed up the healing process or union formation, while the rest of the rootstock is kept dormant

LIGHT

· It has 2 major components which are:

· -light intensity

· -light duration or photoperiod

· Light management is critical for the

rooting of cuttings,
germinating seeds
growing of seedlings
shoot manipulation of explants

· Light can be manipulated by controlling the

1. irradiance, which refers to the relative amount of light measured as radiant energy per unit area

2. light duration (photoperiod)

3. light quality

Daylength

· Long-day plants: these are plants whose physiological response is evoked or triggered when critical photoperiod is equalled or exceeded

· Short-day plants: these are plants whose physiological response is evoked when the critical photoperiod is not exceeded e.g. chrysanthemums

· Day-neutral: these are plants that do not respond to variation in photoperiod e.g roses

· Dahlia cuttings need short days for them to form tubers. Larix spp seeds require long days to germinate.

· Ways of extending short days (winter) include lighting incandescent lights or high intensity discharge lights (HID)

· Under long photoperiods (summer) photoperiod can be shortened by covering the stock plants and cuttings with black cloth or plastic which eliminates light

Light quality (Wavelength)

· Perceived by the eye as colour but usually tallies to a certain range of wavelength(cm)

10-14 10-12 10-10 10-8 10-6 10-4 10-2 100 106

--X-rays------Infra-red------

Cosmic –Gamma------UV-- --solar rays------Radio Waves----

· Red light induces germination in lettuce cultivars while far red light inhibits germination.

· Far red light can promote bulb formation in long day plants such as Allium cepa

· Greenhouse cladding materials used can hyave different spectral quality characteristics hence affecting propagation

GASES AND GAS EXCHANGE

· Aerobic respiration requires oxygen and releases carbon dioxide

· For adventitious root formation and germination of seeds, oxygen must be available. Gas exchange must be promoted at the site of root initiation/seed germination

· Impervious seed coats reduce germination in seeds

· During propagation in enclosed propagation structures eg. Greenhouses, ambient carbon dioxide levels can drop to below optimal levels thereby reducing the photosynthetic rates

· Ethylene gas can build up in the greenhouse, or storage of propagules thereby resulting in deleterious conditions

MINERAL NUTRITION

· Optimal nutrition is required for stock plant to avoid stress

· Nutrients are generally applied to seedlings and plugs by fertigation (ferilisers added to irrigation water)

· Cuttings are normally fertilised with slow-release fertilisers

MODIFICATION OF PROPAGATION ENVIRONMENT

· Propagation Structures

· Greenhouses

· A greenhouse is a structure covered with transparent material for purpose of admitting natural light for plant growth

· Many designs are used in construction of greenhouses. These include A-frame, Quonset shapes and vertical towers

· In large operations several single greenhouses can be joined to form one unit thus eliminating the need for side walls.

HISTORY AND DEVELOPMENT OF GREENHOUSES

Sourced from Doug Bailey,Chair of the Department of Horticulture, University of Georgia, USA

Greenhouses as we know them really began in the 1800's but transparent envelope and provision of heat known back to Roman times - glazing provided by sheets of transparent stone split from laminated minerals. Cultivation of oranges in southern Italy 15th century - called "orangeries." Usually frameworks with clay tile roofs for full or partial protection during cold spells.

In 17th century greenhouses became more common with first glass lites held together via lead just then coming into use. Structures more elaborate, south facing, dense walls on north, east and west side. First greenhouse, an "orangery," fitted with windows in 1591 at the botanic garden at the University of Pisa. Heating was by the use of a stove. 1664 John Evelyn coined the term "conservatory" for a place for conserving delicate plants in winter. Oxford botanic garden 1675. Ham House 1677. Chelsea Physic Garden 1684. Powys Castle 1685. Hampton Court 1690. Kew 1757.

Still there were problems with low light - generally structures were still walls of stone as sides. Invention of putty in 1737 and improved glass technology and the first real lean-to greenhouses led to better light penetration. First lean-to was in 1710 at the Leyden Botanic Garden. In U.S. by 1758 greenhouses not uncommon. First recorded greenhouse in New York City was Beckmans in 1764. By end of 18th century, cast and wrought iron brought improvements and ornamentation. Big glass-making jump by French and imported into Britain by Chance Bros of Birmingham in 1832. Flat sheets. Cost goes down.

First free-standing even span greenhouse was designed in 1806 by Tod, a surveyor and hothouse-builder employed by Sir Joseph Banks. 19th century design enhanced first by Mackenzie's studies of light transmission in 1815 and next by the structural technology developed by Loudon and Paxton.

By 1800 American horticulture had begun to mature. Period of 1800-1915 era of large display houses - conservatories, winter gardens and palm houses. Playground for the rich and famous. Science and education also pushed greenhouse development in the 1800's - botanic gardens at the forefront for study of tropicals. Palm house at Kew 1848. Haupt conservatory at the New York Botanical Gargens 1902. Giant exhibitions. Public groups and city involvement built greenhouses for the pleasure of visitors to parks and gardens. Sparked by interest in public winter gardens in central Europe. The idea began in Berlin but spread westward quickly. First public park in U.S. was in Boston in 1839. New York 1859. Other cities followed. Demand also increased for the small home greenhouse.

Nurserymen first to use greenhouses for commercial purposes - 1827 Loddiges at Hackney - metal houses with curvilinear roofs. Now we have greenhouses in private, public and botanic gardens, and for commercial crop production. Utilitarian and not ornate. They were developed about the same time in North America , Britain, France and Belgium and followed by the Netherlands in the early 1900's. By 1940 crop production in greenhouses was dominated by the Netherlands, the UK and North America, with significant centres in Germany, Scandinavia and Belgium. Initially first crops mainly fruits - particularly grapes. Tomatoes introduced about 1880 and by start of 20th century they were most important crop. Roses, chrysanthemums and carnations grew into the trade followed by other pot plants. Mass produced greenhouses - multi-span design. Within a very short period, commercial production greatly exceeded all other uses.

World War I had a crippling effect on the large country estates. Little development in botanical gardens. End of World WII saw a wide range of new structural materials. Aluminum and galvanized steel came into the world in the early 1950's and by 1960 greenhouse structures of wood had almost ceased. Aluminum allowed long clear spans up to 75' or more. Great expansion after 1950. Netherlands soared into number one in terms of acreage (still there). Early 1960's saw switch to film plastic. Revolutionary. changed the world. Galvanized steel came into heavy use. Explosion in important botanical greenhouses - Climatron at the Missouri Botanical Garden in 1960; six conservatories at the Hamburg Botanic Gardens (1963); the Exhibition Plant Houses at Edinburgh (1967); others.

U.S. greenhouse history - 1st in U.S. 1764, Beckman, in NYC - needed close proximity to markets - vegetables out of season, then floral crops - Rail first and then trucks dominated trade till the 1950's, then air shook up the system as far as cut flower production - could now grow in mild climate with low costs, then ship to urban, tougher clime, high pop centres - Air transport killed and gave birth to floral industries - 1989: California took 82% chrysanthemum pompom crop, 82 % std chrysanthemum, 82% carnation, 67% tea rose, 53% sweetheart rose. Of total fresh flowers in U.S. Calif takes little over 50%! Why: heat costs lower and air transport west to east cheaper. Trucks looking more competitive all the time but still most by air. Growth in landscape bedding plants big impact on the industry.

History of Greenhouse Development

Approximate Date / Location / Event
BC
4000 / Egypt / Grape culture depicted on tomb of Ptah-hotap at Memphis
2737-2697 / China / Wen-Wang established ceremonies for sowing of vegetables and cereals
427-347 / Greece / Plato mentions protected cultivation
300 / Greece / Theophrastus notes that rotting manure warms and "ripens" the soil and hastens crop maturity; writes of "adonis gardens" (i.e. potted plants)
92 / Italy / Sergius Orata invented heating system, with passage of combustion gases (heat) through flues in floor
AD
1-100 / Italy / Columella describes use of mica (translucent) sheets to protect plants and temper sunlight for young plants
14-37 / Italy / Tiberius Caesar used: "lapis speculare" (translucent slabs of mica (musconite), alabaster (selenite), or talc) for "horte pensiles" (hotbeds on wheels)
23-79 / Italy / Pliny describes use of straw caps to protect young plants
380 / Italy / roses forced by pouring warm water into nearby trenches twice a day
12th Century
Europe / crusaders bring back many exotic plants
14th Century
1385 / France / flowers grown in a glass pavilion turned to the south
15th Century
1490 / Italy / trees in tubs and overwintering of trees in wooden sheds described by Pontano
16th Century
Europe / Renaissance period; origins of the Middle Class; wintering sheds with open flues first reported
1500s / Italy / Great glass industry progresses; probably manufacture of glass bells to cover plants
1500s / England / Jacob flowers carnations in a glasshouse during winter; used solar heating
1530 / Germany / Fugger of Augsberg builds orangery probably imported from Italy
1550 / Italy / first botanical garden with greenhouse at Padua
1597 / France / Gerrarde's Herbal describes plant beds insulated with mats, cloth, straw, etc. during cold nights and/or days
17th Century
Europe / orangeries with glass south sides and stoves (Hybernaculums, stove houses)
1602 / The Netherlands / Dutch East India Company founded; The Netherlands well on the way to becoming the shipping leader and sea power leader
1610-1643 / France / Claude Mollet describes frames covered with glass panes and heated with manure
1611 / Germany / subtropical trees in Stuttgart protected by removable sheds ("orangery sheds")
1626 / France / Jardin des Plantes with greenhouses established in Paris
1630 / Germany / brick castle garden designed by de Caus built in Heidelberg; side glass and roof removed in summer
1631 / England / summer bulbs forced on wheeled cart by night frost protection in building
1632 / England / Oxford conservatory built and heated with burning charcoal in a metal wagon
1650 / France / orangery exists with trees and flowers in Vincence
1658 / Sweden / Uppsala greenhouse (orangery) built
1660 / England / forcing frames used
1668 / England / Lord Sandwich notes burning of high-sulfur coal in greenhouse kills plants
1670 / The Netherlands / covered frames used
1675 / England / Evelyn first heats greenhouses with warm water system