Micronutrients (Trace Elements) Micronutrients (trace elements or microelements) are essential elements utilized by plants in very small amounts. Low-analysis fertilizers such as 5-10-5 have trace elements as impurities. High-analysis fertilizers may be fortified with micronutrients. BORON (B) Boron is absorbed by plants as borate (BO 2 4 ). Mobile in the plant system, it affects flowering, fruiting, cell division, water relations (translocation of sugars), and other processes in the plant. When deficient, symptoms appear at the top of the plant. Terminal buds die, producing growth described as witches’-broom. Lateral branches grow and form rosettes; young leaves thicken and become leathery and chlorotic. Stems become hollow and may crack. IRON (FE) Though more abundant in most soils than other trace elements, iron deficiency occurs in alkaline or acidic soil. It can be absorbed through leaves or roots as Fe 2+ ions (and also as Fe 3+ ions to a much smaller extent since availability is reduced by being bound in plant tissue). Iron chelates can also be absorbed. Iron is a component of many enzymes and a catalyst in the synthesis of chlorophyll. Iron deficiency shows up as interveinal chlorosis of young leaves. In severe cases, leaves may become whitish, since iron plays a role in photosynthesis, as indicated previously. Iron is immobile and thus deficiency appears first in younger leaves. MOLYBDENUM (MO) Vegetables, cereals, and forage grasses are among a number of species that are known to show very visible symptoms when molybdenum is deficient in the soil. This element is unavailable to plants grown under very low pH (highly acidic) conditions. In such cases, liming is employed as a corrective measure. Molybdenum is involved in protein synthesis and is required by some enzymes that reduce nitrogen. The leaves of cauliflower and other cruciferous plants become narrow (whiptail) when the element is lacking in the soil. Plant leaves may also become pale green and roll up. MANGANESE (MN) Manganese, absorbed as Mn 2+ ions, is crucial to photosynthesis because of its role in chlorophyll synthesis. It is also important in phosphorylation, activation of enzymes, and carbohydrate metabolism. It is not mobile in plants. When deficient, interveinal chlorosis is observed in younger leaves, just as in iron deficiency. ZINC (ZN) Zinc is an enzyme activator. It is absorbed as Zn 2+ ions by plant roots and tends to be deficient in calcareous soils that are high in phosphorus. When deficient, plant leaves are drastically reduced in size and internodes shortened, giving a rosette appearance. Interveinal chlorotic mottling may occur in young leaves. Kalanchoe is particularly susceptible to zinc deficiency as a greenhouse plant. In species such as peach and citrus, deficiency of zinc produces a type of chlorosis called mottled leaf. COPPER (CU) Soils that are high in organic matter are prone to copper deficiency. Copper is important in chlorophyll synthesis and acts as a catalyst for respiration and carbohydrate and protein metabolism. Younger leaves may show interveinal chlorosis while the leaf tip remains green; with time, the leaf blade becomes necrotic. Terminal leaves and buds die, and the plant as a whole becomes stunted. Copper sulfate or copper ammonium sulfate may be administered to leaves or soil to correct deficiency problems. CHLORINE (CL) Chlorine is absorbed by plants as chloride ions (Cl ). Deficiency in the field is rare. An excessive level of chlorine is more often a problem than its absence. When deficiency occurs in the soil, plants may be stunted and appear chlorotic, with some necrosis. Micronutrient A chemical element that is required in small amounts (usually less than 1 ppm) for the growth and development of plants. 4.3.2 SOIL ORGANIC MATTER Organic matter in the soil may result from plant or animal materials. Plant residue or green manure crop incorporated into the soil by tilling the decaying plant roots is a good source of organic matter. Plant matter such as dried leaves on the surface of the soil is not 4.3 Belowground (Soil) Environment 113
Soil Erosion The wearing away of the land surface by geological agents such as water, wind, and ice. considered organic matter until it is incorporated into the soil. Soil erosion depletes soil organic matter. Organic matter is important to soil productivity since it is a source of nutrients when it decomposes. It improves soil structure by binding together mineral particles into aggregates for better aeration and drainage. It helps to buffer soils against rapid changes in pH. Organic matter increases the water-holding capacity of soils and gives them their characteristic dark brown or black color. Microorganisms (e.g., bacteria, fungi, and actinomycetes) are responsible for decomposing plant parts for easier incorporation into the soil. Sugars, starches, proteins, cellulose, and hemicellulose decompose rapidly, whereas lignin, fats, and waxes are slow to decompose. Organic matter acts as a slowrelease fertilizer, since its nutrients are released gradually over a particular period. Humus is a very stable part of the soil organic matter. Much of humus is formed from two general biochemical processes. The chemicals in the plant residue undergo decomposition by microbial action to produce simpler products. These breakdown products undergo synthesis, by which the simpler products are enzymatically joined to make more complex products such as polyphenols and polyquinones. These synthetic products interact with nitrogen-containing amino compounds to produce a great portion of resistant humus. Further, the synthetic process is aided by the presence of colloidal clays. Humic particles (or humic micelles) carry a large amount of adsorbed cations (e.g., Ca 2+ , Mg 2+ ,H + , and Na + ) as clay micelles. 114 Chapter 4 Plant Growth Environment 4.3.3 SOIL REACTION AND NUTRIENT AVAILABILITY A soil test showing that adequate amounts of a nutrient are present does not indicate its availability to the plant. In addition to adequate amounts, the presence of moisture is critical, because water is the medium in which solutes are transported through the plant. Other factors that interfere with nutrient availability are soil temperature and soil reaction, or pH. Plant processes are generally slowed down by low temperatures. Soil reaction, or pH, is a measure of the hydrogen ion concentration as an indication of the soil’s degree of acidity or alkalinity. A pH of 7 is neutral. Values above 7 are considered alkaline, and values below 7 are acidic. The pH scale is logarithmic (Figure 4–11), meaning that a soil pH of 5 is 10 times more acidic than a soil pH of 6 and a pH of 4 is 100 times more acidic than a pH of 6. Most horticultural crops tolerate a soil pH within the range of 4 to 8. Soil pH regulates nutrient availability. Figure 4–12 shows the relationship between pH and nutrient availability to plants. A pH of7±1appears to be a safe range for most nutrient elements in the soil. Only iron is available at a strongly acidic pH. Conversely, iron is deficient in the soil under alkaline conditions. Sensitive plants (such as bluegrass [Poa pratensis]) develop iron-deficiency symptoms called iron chlorosis, a condition in which young leaves lose their green color and become yellowish. The difference between this kind of chlorosis and that associated with nitrogen deficiency is that iron chlorosis occurs between the veins of the leaves (interveinal chlorosis) and nitrogen causes a more uniform yellowing of leaves. Soil pH affects the biotic population of soil. Fungi tend to prefer highly acidic conditions (pH of 4 to 5), and nitrogen-fixating bacteria (Rhizobia) prefer a pH range of between 6 and 8. Table 4–8 shows the pH requirements of various horticultural plants. Factors That Affect pH Soil pH may rise in a soil that experiences low rainfall or is poorly drained. Salts tend to accumulate under these conditions. Soils formed on calcareous parent material have high alkalinity. Acidic soils (low pH) occur when soils are exposed to heavy rainfall and good drainage such that the bases are leached into lower depths or washed away in the runoff. Correcting pH Low soil pH may be corrected in practice by adding limestone (CaCO 3 ) or gypsum (CaSO 4 ) to the soil to raise the pH. The choice depends on the soil pH and other characteristics. To lower soil pH, sulfur compounds are added to the soil. Nitrogen fertilizers also tend to
HORTICULTURE Principles and Practic
HORTICULTURE Principles and Practic
With love to Theresa, quarterback;
Brief Contents Preface xxi PART 1 T
Contents Preface xxi PART 1 THE UND
5.3 PLANT GROWTH PROCESSES 160 5.4
8.20 COMMON GREENHOUSE DISEASES 276
12.3 INTERNAL ENVIRONMENTAL CONTROL
PART 6 Summary 541 References and S
22.18 INDOOR COMPOSTING SYSTEMS 668
Preface Horticulture is the area of
ACKNOWLEDGMENTS I am very grateful
PART 1 THE UNDERLYING SCIENCE CHAPT
1 What Is Horticulture? PURPOSE AND
(a) (c) (b) (d) FIGURE 1-1 The many
FIGURE 1 Bridge. The plaza view of
CYCADS Many people mistake these pr
FIGURE 2 The world's largest unbran
FIGURE 2 Sold flowers are loaded on
FIGURE 1-4 Formal landscaping featu
1.4 ROLEOFTHENURSERY AND SEED INDUS
1.5 HORTICULTURE AND SOCIETY Hortic
TABLE 1-3 U.S. Horticultural Export
Turfgrass Operation 1. Landscape te
What Is Horticulture? This site pro
Examples of botanical gardens http:
2 Classifying and Naming Horticultu
Eight major taxa are commonly used
TABLE 2-3 The Divisions of the King
HISTORY OF PLANT TAXONOMY PAUL R. F
AGE OF HERBALISTS Two major events
possible system of nomenclature. Ho
TABLE 1 Type Categories for Plant N
2.3 OTHER CLASSIFICATION SYSTEMS (O
2. Shrubs. A shrub has no main trun
Simple Fruits Fleshy Fruits Drupe B
FIGURE 2-14 A pome, represented by
2.3.5 CLASSIFICATION OF VEGETABLES
(a) (b) FIGURE 2-22 (Source: George
FIGURE 2-25 A narrowleaf plant. (So
FIGURE 2-29 Parts of a typical gras
such as rosemary, sage, thyme, marj
c. Leaves d. Bulbs 2. Cut across (t
CO 2 FIGURE 5-6 The C 4 pathway of
Growth and Development The general
TABLE 5-2 Energy Produced from Aero
Certain plants are adapted to dry e
conditions exist to sustain growth
Shoot Elongation In certain plants,
for success, since high temperature
FIGURE 5-13 Ripening of plantain sh
Terminal bud removed Unbranched pla
conditions—pertaining to light, m
them to maturity. The major process
6 Breeding Horticultural Plants PUR
Similarly, there can be no plant br
APPLICATION, CHALLENGES, AND PROSPE
hit with target DNA. Therefore, it
Generally, within ten days of exper
Aziz A.N., Sauve R.J., Zhou S., 200
(b) F 1 Rr Rr round round F 2 RR R
e.g., Aa × Aa), the lethal allele
eeder’s equation. Simply stated,
Before the seed or product becomes
6.18.2 THE GENERAL STEPS OF RDNA TE
2. Political disagreement. There ar
REFERENCES AND SUGGESTED READING Ac
PART 2 PROTECTING HORTICULTURAL PLA
7 Biological Enemies of Horticultur
8. Weeds may clog drains, waterways
is also a root parasite that obtain
LEGISLATIVE Both state and federal
Example Integrated cultural, physic
7.4.2 IMPORTANT INSECT ORDERS Insec
Egg FIGURE 7-3 Life cycle of an ins
sucking insects (also found with so
FIGURE 7-12 Corn earworm damage. (S
TABLE 7-1 Selected Fungal Diseases
7.6.1 SMALL ANIMALS Rabbits, mice,
FIGURE 7-16 The disease triangle. P
fungitoxic exudates in its leaves,
SUMMARY Insects are a major class o
For the home growers or those who c
for consumers and the environment).
TABLE 8-1 Strategy 4: Strategies an
gibberellic acid spray overcomes st
In a competitive industry, a variet
Chemicals gain access to humans thr
2. Pesticide management. Controllin
Every organism has its natural enem
TABLE 8-3 Selected Examples of Biol
1 2 YEAR 3 4 FIGURE 8-5 cycle. A cr
6. Heat treatment. In the greenhous
Organic Compounds (Organics) Organi
under enclosed conditions (e.g., wa
FIGURE 8-9 A tractor-mounted spraye
8.11.9 LANDSCAPE PESTS AND THEIR CO
application, a particular herbicide
Further, they do not provide unifor
SUMMARY Herbicides are chemicals us
Sulfur may be applied for both prev
8.23 PREVENTING GREENHOUSE DISEASES
PART 3 PROPAGATING HORTICULTURAL PL
9 Sexual Propagation PURPOSE AND EX
Anther Microspore Megaspore mother
Lettuce seeds Red light Darkness Fa
FEDERAL AND STATE SEED LAWS Federal
Germination Test In laboratory prac
FIGURE 15 The essential structures
processing into flour or meal). How
physiologically immature seeds must
seeds may be treated in this way be
The two basic modes of seedling eme
locations in the field. Home garden
FIGURE 9-9 A plastic flat. (Source:
(a) (b) FIGURE 9-12 (a) Sowing seed
y the gardener or grower. Whatever
REFERENCES AND SUGGESTED READING Co
species enables vegetative propagat
for rapid rooting. There are two ba
Cutting involving one node (e.g., s
This practice is especially importa
10.6.4 STICKING THE CUTTING Cutting
(a) Indexing by budding Diseased pl
10.11 M ETHODS OF GRAFTING Grafting
Scion Wax FIGURE 10-17 Steps in bar
MODULE 3 BUDDING 10.12 TYPES OF BUD
MODULE 4 LAYERING 10.13 TYPES OF LA
Buried part of shoot is nicked FIGU
variety of ways. In air layering, a
FIGURE 10-34 by using cormels. Prop
Psuedobulbs In the Dendrobium orchi
The technique is used widely in cro
PART 4 GROWING PLANTS INDOORS CHAPT
11 Growing Houseplants PURPOSE AND
TABLE 11-1 Common houseplants Commo
Saddle leaf Philodendron selloum To
Window Displays Plants in windows e
CONTAINER GARDENS DR. TERRI W. STAR
annuals and hardy perennial species
of the large container filled with
perfection about four to six weeks
FIGURE 11-6 Flowers displayed on th
TABLE 11-5 Plant Selected Plants fo
The lighting condition near these w
Fluorescent Lights Fluorescent ligh
may be used for one pot or a group
garden rooms, atriums, or a large c
The photoperiod affects when the ho
patted firm to keep the plant erect
Other Materials Apart from clay and
(a) ( FIGURE 11-25 Support for plan
TABLE 11-7 Common Problems of House
• Keep soil moist all the time
• Prefers high temperatures • P
amount and quality of light. If sup
12 Controlled-Environment Horticult
6. Curvilinear 7. Curved eave 8. Do
Detached greenhouses have several a
12.2.3 FRAME DESIGN There are two b
horticultural business a less-expen
Texas, Hawaii, and California. The
source of heat for times when the t
FIGURE 12-17 Greenhouse production
FIGURE 12-21 Moving tables allowing
Research program on greenhouse engi
greenhouses equipped with a variety
FIGURE 1 Annual energy required per
This system was demonstrated in a 5
FIGURE 6 Amounts of waste energy ut
Ekholt, B.A., D.R. Mears, M.S. Gini
or object to be warmed. Failure to
objects in its path (e.g., the floo
FIGURE 12-27 Motorized ventilation
FIGURE 12-30 Movable internal shade
FIGURE 12-33 A high pressure sodium
Source of Water The quality of loca
FIGURE 12-37 Overhead sprinkler irr
Intermittent Feed Greenhouse plants
However, in winter, greenhouse vent
OUTCOMES ASSESSMENT 1. Explain the
. Foliage or green plants. Foliage
2. Labor. The size of the labor for
FIGURE 13-1 Greenhouse production o
FIGURE 13-2 Lettuce plug is inserte
13.8.4 AGGREGATE HYDROPONIC SYSTEMS
(a) (b) (c) FIGURE 13-6 Plug produc
14 Growing Succulents PURPOSE AND E
FIGURE 14-3 Leaf succulent represen
frost-hardy. Their rosettes are usu
TABLE 14-1 Plant Selected Popular S
(a) (b) FIGURE 14-12 Typical bromel
14.7.1 WHAT ARE CACTI? 14.7 CACTI C
FIGURE 14-16 Opuntia. (Source: Crai
FIGURE 14-23 Mammillaria. (Source:
FIGURE 14-28 Both desert and jungle
Growing mix Gravel Cacti (a) (b) FI
PART5 GROWING PLANTS OUTDOORS: ORNA
15 Principles of Landscaping PURPOS
8. Create recreational grounds. Suc
knowledge, with concern for resourc
(a) (b) (c) FIGURE 15-2 The occurre
GUIDELINES FOR LANDSCAPE DESIGN DAV
the landscape. Some very successful
Rhythm and Line Panoramic view of a
FIGURE 15-10 A formal garden. The e
How frequently do they entertain? A
the patio should be located on the
15.7.1 SELECTING PLANTS A homeowner
Plant Arrangement in the Landscape
Shadow FIGURE 15-15 Planting a tree
SUMMARY Landscaping enhances the su
3. Supply materials on a timely bas
such as preparation rooms (for mixi
of environmental fluctuations. Furt
FIGURE 16-4 A bare-root tree seedli
17 Installation of the Landscape PU
for walks, driveways, and patios (F
Planting may be limited to accentin
17.3.3 PREPARING THE BED The soil s
FIGURE 17-4 Bedding plants raised i
SUMMARY Bedding plants are largely
TABLE 17-6 Selected Ground Covers T
TABLE 17-7 Selected Ornamental Gras
they determine the success and surv
12. Wildlife attraction. Trees in t
pennsylvanica), hackberry (Celtis s
y winds. A stake, which is often a
TABLE 17-8 Selected Narrowleaf Ever
TABLE 17-11 Selected Deciduous Shru
Blooming bushes 1. Blue mist shrub
Planting Bulblets and Bulbils Speci
may be divided such that each secti
FIGURE 18-1 (Source: George Acquaah
Cool-Season (Temperate) Grasses In
Growth Habit Turfgrasses are the mo
Heavy Use Lawns on playgrounds and
The seed should be free from weeds
Source of Sod As with seed, sod sup
A plug of sod FIGURE 18-7 Plugging
way, plants are able to adapt to th
form of a can placed on the lawn wi
TABLE 18-3 Some Common Lawn and Tur
even surface soil surface for layin
MacCaskey, M. 1987. All about lawns
Pruning is sometimes done in conjun
4. Pruning may be done to reduce th
19.4.2 SAWS A saw may be designed t
defeat the purpose of pruning. The
Bud withers as cut end dries back d
19.6 STRATEGIES FOR PRUNING ABOVEGR
Rejuvenation Pruning Cut canes to a
3. In the third and subsequent year
(a) Cut Prune (b) FIGURE 19-16 Step
Eucalyptus and Paulownia are amenab
TRAINING & PRUNING DECIDUOUS FRUIT
Summer pruning eliminates an energy
a) b) FIGURE 2 Newly planted apple
FIGURE 6 Wooden limb spreaders can
FIGURE 9. An apple tree trained to
years to promote continued lateral
Horizontal Espalier The horizontal
19.16.1 CANE FRUITS Cane fruits are
FIGURE 19-26 Shearing of Christmas
pyramid-like form that is wider at
After selecting the appropriate spe
PART 6 GROWING PLANTS OUTDOORS: VEG
20 Growing Vegetables Outdoors PURP
The National Agricultural Statistic
(This item omitted from WebBook edi
growers should take to determine an
pests and reduce/ eliminate hail da
square yard (10 to 68 grams per squ
High tunnels help increase the prof
(This item omitted from WebBook edi
20.4 VEGETABLE MARKET TYPES Fresh V
Establishing the Crop Planting into
home water supply from the tap. Thi
Cole crop Cabbage Root Potato Bean
6. Adequate nutrition. While overfe
variable, ranging from creamy yello
There are two general production pr
This toxin is heat resistant and no
large, or jumbo. The bulb may be sw
REFERENCES Growing selected vegetab
TABLE 21-1 Popular Herbs and Their
(a) (b) (c) (d) (e) (f) FIGURE 21-1
22 Organic Farming PURPOSE AND EXPE
22.3 PRINCIPLES OF ORGANIC FARMING
and the specific materials to be us
22.8 MANAGING SOIL PHYSICAL QUALITY
preemergent or early postemergent o
Composting is a deliberate activity
22.14.5 THE CARBON-TO-NITROGEN RATI
Moisture Supply Water is required b
Compost materials FIGURE 22-4 a wir
As microbial decomposition proceeds
Establishment and Management of an
night, freezing can occur in spring
accomplished by stratification. It
transmitted by the dagger nematode
PART 7 SPECIAL TECHNIQUES AND HANDL
24 Cut Flowers and Floral Design PU
to more than four-fold in standard
Temperature and Humidity Wilting re
FLORAL DESIGN: AN OVERVIEW BY WM. J
Principle Definition Types (or Uses
pH value-a measure of the acidity o
FIGURE 6 Parallel Design-Parallel d
24.3.2 TOOLS AND MATERIALS The tool
3. Establish the focal point. 4. Ad
Natural Drying To dry naturally, fl
24.4.3 DRIED FLOWER ARRANGEMENTS Dr
25 Terrarium Culture PURPOSE AND EX
FIGURE 25-3 Terrarium containers ar
FIGURE 25-5 Assortment of tools use
25.6.7 ENHANCING THE DISPLAY Certai
(a) (b) FIGURE 26-1 Bonsai can be c
TABLE 26-3 Plant A Selection of Pop
26.3.1 COLLECTING BONSAI PLANTS FRO
Strip bark Bare branch FIGURE 26-9
26.5.2 SANITATION It is critical to
27 Postharvest Handling and Marketi
whereas oranges are picked (they ha
(b) (a) (c) (d) (e1) (e2) (f) FIGUR
To reduce packaging injury, contain
is replaced by the by-product of re
Stored produce may lose some color,
with pricing. When selling by volum
(a) (b) FIGURE 27-5 Horticultural p
APPENDIX A Temperature: Converting
APPENDIX B Metric Conversion Chart
APPENDIX D Common and Scientific Na
Pecan (Carya illinoensis) Peony (Pa
GLOSSARY A Abaxial Turned away from
Cellulose A complex carbohydrate th
Floriculture The science and practi
M Macronutrient An essential elemen
Root cap A mass of hard cells cover
INDEX A-frame, 395 A-horizon, 108 A
defined, 390 fertilization, 432-434
Radiant heaters, 378 Radicle, 90 Re
color plate 1 (a) (b) (c) (d) (e) M
color plate 3 (b) (a) (c) (d) (e) (
color plate 5 (a) (b) (d) (c) (e) (
color plate 7 (b) (c) (d) (a) (e) (
color plate 9 (a) (b) (c) (d) (e) (
color plate 11 (a) (c) (b) (d) Grow
color plate 13 (a) (b) (c) (d) (e)
color plate 15 (a) (b) (c) (d) (e)
color plate 17 (a) (b) (c) (d) (e)
color plate 19 (a) (b) (c) (d) (e)
color plate 21 (a) (b) (c) (e) (d)
color plate 23 (c) (b) (a) (d) (e)
color plate 25 (c) (a) (b) (d) (e)
color plate 27 (a1) (a2) (b2) (b1)
color plate 29 (a) (b) (c) (d) (e)
color plate 31 (a) (b) (c) Floral d
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