Horticulture

Summary

Horticulture is both a science and an art and includes the propagation and cultivation of plants often associated with gardening. Trees, bushes, grasses, and fungi are typical naturally occurring plant materials. Cultivated plants include not only trees, shrubs, grasses, and fungi but also vegetables, fruits, nuts, herbs, spices, ornamentals, and flowers. Although horticulture has existed since ancient times, modern scientific advances in the field have resulted in many practical uses of plant materials, including the development of pharmaceuticals. Genetics plays a significant role in modern-day horticultural practices, especially in areas such as food production.

Definition and Basic Principles

Horticulture is the art of aesthetically arranging plant materials and the science of breeding, propagating, and growing plants. Horticulture requires a knowledge of landscape design, plant science, and individual plants. The ability to identify plants and their growing needs is necessary for determining how to use plant materials in landscape designs and also in plant breeding and propagation.

Plants are classified as herbaceous or woody. Woody plants include deciduous and evergreen trees, shrubs, and smaller plant materials. Deciduous plants become dormant at the end of the growing season, and plants classified as evergreens will retain their foliage—needles and broad leaves—throughout the year.

Horticulture is not the same as agriculture, which involves growing crops on a much larger scale than the typical horticultural venture and may also include animal production. Horticulture can be pursued either as a hobby or as a commercial pursuit. Those involved in horticulture need to be versed in many disciplines. Design, planning, graphics, and construction engineering are important for the art of horticulture, and a background in math and biochemistry is needed for horticultural science.

Background and History

Horticulture is associated with ancient botany, which began as early as the fourth century Before the Common Era (BCE). Plants were selected and domesticated, and early propagation practices such as grafting can be seen in artwork found in ancient Egyptian tombs. Classical philosophers, such as Aristotle, defined plant types and developed some of their early uses for food, drugs, and fuel. Although an interest in botanical sciences waned during the Middle Ages, monasteries were known for their gardening prowess. During the eighteenth and nineteenth centuries, gardening became important as an art form, especially in Europe and Asia, and horticulture as a science began to expand.

One of the first modern horticulturalists in the United States was Liberty Hyde Bailey, a graduate of Michigan Agricultural College. As is true of many horticulturalists, Bailey wrote many texts on botany and horticulture. Bailey also worked with President Theodore Roosevelt's administration to improve rural life through horticulture. Early landscape architects, such as Frederick Law Olmstead, were also instrumental in advancing the field of horticulture.

How It Works

A horticulturist must be cognizant of soil, light, temperature, and water conditions to propagate and cultivate plants. Horticulture begins with the preparation of soil through tilling and fertilization unless the plant is grown without soil, as in hydroponics. Light and temperature can be controlled by beginning plant cultivation inside greenhouses and transplanting plants to the outdoors when light and temperature are optimal for growth. Installation of water collectors and irrigation systems, which have been part of horticulture since ancient times, is also necessary. Xeriscaping with modified drought-resistant plant materials, however, has reduced the reliance on water in some locations. Control of pests and diseases is also important, although many pest- and disease-resistant plant materials exist because of modern technology. Some horticulturalists no longer rely on chemical fertilizers and pesticides, and organic gardening is becoming profitable because of the public demand for naturally grown foods. Horticulture may also involve modern harvesting and handling practices that use more mechanical methods than manual labor.

Propagation. Propagation techniques vary from microscopic techniques such as gene splicing and producing tissue cultures to plant breeding and employing natural and cultivated plant structures and cuttings to generate new plants. The most common form of plant propagation is with seeds. Vegetables and flowers are typically propagated in this manner.

Clonal propagation can be done naturally or achieved through scientific methods involving plant structures rather than seeds. Some examples of natural clonal propagation through plant structures include strawberry runners, potato tubers, crocus corms, daffodil bulbs, and Calla lily rhizomes. Scientific propagation can be as simple as placing cuttings of shoots, roots, and leaves into water or moist soil. Shoots, such as willows, will regenerate roots. Roots, such as sweet potatoes, will grow new shoots, and leaves, such as African violets, will grow both new shoots and roots.

More complex clonal propagation methods include grafting techniques that physically join the parts from two plants together (often used in the propagation of fruit trees) and micropropagation, which requires horticulturalists to grow plant cells and tissues artificially. Micropropagation is used in the production of modified plants that may have desirable qualities such as pest and disease resistance. It enables the production of a greater number of hardier plants in a shorter amount of time than could be produced from seeds or other propagation methods in the same amount of time.

Cultivation. Cultivation involves the direct planting of seeds and plant structures or the transplanting of plants that were started elsewhere. Cultivation of plant materials requires pruning and weeding to enhance future growth and improve a plant's appearance. Ornamental cultivation techniques might include training plants so that they are reoriented to better conditions, such as light. Dwarfing is an ornamental cultivation practice that is often used in Asian cultures. Ornamental horticulture is important for those involved in floriculture and landscape architecture.

Applications and Products

Plants are everywhere and are necessary to sustain life. The practice of horticulture, therefore, has multiple applications that are important to society. In addition, modern technology has resulted in a greater diversity in plant-based products.

Food Production.Plant biotechnology includes genetic engineering, which allows the exchange of genes between plant species, usually ones that are closely related. More than 70 percent of processed foods are believed to contain some ingredients that have been genetically engineered, and biotech crops, such as corn and soybeans, are on the rise. New horticultural technologies and research are especially important in global regions where horticultural production is restricted because of marginal climate conditions, poor soils, lack of water for irrigation, and reduced land resources for cultivation. DNA plays a major role in plant breeding of both quantitative and qualitative traits. Developing nations must especially depend on horticultural research to breed plants with pest- and drought-resistant characteristics to expand productivity on less acreage.

The global food market is changing. The ability to transport food products longer distances and the improved shelf life of such food are the result of horticultural advances that have opened up new markets for foods that may be exported by small producers in developing nations. Moreover, the methods of producing food are changing, and horticulturalists are finding ways to meet society's desire for more natural and organic food products while sustaining and protecting the environment.

Pharmaceuticals. Herbal remedies and medicinal plants have been used by healing practitioners since ancient times. Although scientists have questioned the curative powers of some herbs, horticulture continues to play an important role in the breeding of plants used as alternative medicines and in the development of plant-based mainstream drugs. Horticulturalists are also involved in synthesizing plant compounds into new medicines. Rainforest plants have become especially important in this research because of the many naturally occurring chemical defenses against pests and diseases that these plants exhibit. Horticulturalists are at the forefront of conducting research concerning the curative properties of naturally occurring chemical compounds found in plants. These chemicals, known as phytochemicals, may provide new drugs for fighting cancer.

Flavors and Fragrances. The cultivation of plants, such as flowers and fruits, is necessary to produce many diverse products. Among these are cosmetics, perfumes, and food flavorings. Plant breeding and genetic engineering have enhanced the quality of plant-based flavorings, thus making some foods more palatable.

Farms and Nurseries. Horticultural practices play an important role in any enterprise that involves the growing of plants for commercial, public, or private uses. Tree farms range from farms specializing in the production of Christmas trees to those providing trees for forest conservation, which protects the environment by providing flood control and carbon sequestration. Other farms may produce vegetables, flowers, or turf. Golf course, park, and garden designers depend on farms and nurseries to produce plant materials to implement their plans.

Energy Production. Horticulture plays a role in the production and breeding of plants that can be converted into biofuels. Although the biofuel industry is in its infancy, substantial global research is taking place. For example, Clemson University has conducted research to turn discarded peaches into hydrogen gas, and nations such as India have produced biodiesel from inedible plant oil seeds. Sugarcane and maize have also been used to produce ethanol. Because diverse plants can be used to produce biofuels, developing nations may be able to create biofuels cheaply by using naturally growing plant materials and thus create new industries to sustain population growth. However, horticulturalists must ensure that sufficient plants are available for both food production and these emerging biofuel industries.

Education. Development of healthy eating habits has become an important goal in many developed nations, such as the United States, where obesity increased substantially between the 1980s and 2010s. Educators are employing gardening and horticulture in their lesson plans to teach children about nutrition. In less-developed countries, where poor nutrition is caused by a lack of horticultural crops, international organizations such as the United Nations provide education not only on advanced production and cultivation practices, including irrigation and pest control, but also on food safety, conservation, and marketing.

Therapy. Horticulture and gardening are therapeutic for those with learning, mental health, and physical disabilities. The American Horticultural Therapy Association is one of several organizations involved in this growing practice. Horticultural therapists incorporate gardens into wellness programs, and this type of therapy has become popular in programs to treat alcohol and substance abusers.

Careers and Course Work

Horticultural careers include gardening and landscaping, which may require little education, and scientific careers, such as plant breeding and genetic engineering, for which advanced degrees are required. A Bachelor of Science degree in horticulture or a related field prepares a student for careers that include plant and crop cultivator and plant disease or pesticide specialist. Governmental careers such as extension work are also popular. A dual bachelor's degree in business administration and horticulture would support work in a greenhouse, nursery, garden center, or golf course. Those interested in garden and landscape design might seek a bachelor's degree in landscape architecture.

Students interested in plant biotechnology, one of the fastest growing fields, can work in research laboratories as technicians or research scientists. Many who have gained a doctorate degree in biotechnology work in educational settings and continue to conduct horticultural research. Biotechnologists are sought by governmental agencies and private industry, especially companies associated with food production and pharmaceuticals.

Basic courses for students seeking a career in horticulture include plant biology, botany, and plant materials. More advanced coursework includes entomology, plant physiology, breeding and propagation, plant nutrition, and plant pathology. Specialized educational courses might include floriculture, for those who want to work with flowers or arboriculture, for those interested in caring for trees. Students interested in an advanced degree, such as biotechnology, must expand their coursework to include biochemistry, genetics, and molecular science.

Social Context and Future Prospects

As the worldwide population continues to increase, horticultural advances through biotechnology can benefit society by ensuring an adequate food supply. Genetically engineered plants are more pest- and disease-resistant, and modified plants that withstand cold temperatures and are more tolerant of drought and salt allow for longer growing seasons and more numerous habitats. Plants are being genetically engineered to have superior nutrient properties that could reduce the quantity of food necessary to nourish the world's growing population. Furthermore, many of the plants created through biotechnology and genetic engineering are playing a greater role in the production of beneficial medicines and drugs; some experts predict that society may one day have access to edible vaccines.

However, these scientific advances are raising concerns. Scientists are debating whether genetically engineered foods could produce gene mutations in organisms that consume them, create new food allergens, or cause environmental damage because of the antibiotic resistance of genetically engineered foods. Cross-pollination has also become an issue, as it cannot be prevented or stopped. Some fear the creation of super weeds that cannot be controlled after naturally occurring weeds cross-pollinate with genetically modified, pesticide-resistant plants. Still, horticulturalists continued to innovate in the twenty-first century, balancing the scienctific and aesthetic focuses of the field. Automation of horticultural operations through mobile technologies, drone usage, and new soil types are just a few of the advances made in horticulture. 

Bibliography

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