Botany as a science

Размещено на http://www.allbest.ru/

Botany

Botany, plant science(s), or plant biology a discipline of biology, is the science of plant life. Traditionally, the science included the study of fungi, algae, and viruses. botany nutrition plant farming

Botany covers a wide range of scientific disciplines including structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary relationships among taxonomic groups. Botany began with early human efforts to identify edible, medicinal and poisonous plants, making it one of the oldest branches of science. Nowadays, botanists study about 400,000 species of living organisms.

The beginnings of modern-style classification systems can be traced to the 1500s-1700 when several attempts were made to scientifically classify plants. In the 19th and 20th centuries, major new techniques were developed for studying plants, including microscopy, chromosome counting, and analysis of plant chemistry. In the last two decades of the 20th century, DNA was used to more accurately classify plants.

Botanical research focuses on plant population groups, evolution, physiology, structure, and systematices. Subdisciples of botany include agronomy, forestry, horticulture, and paleobotany. Key scientists in the history of botany include Theophrastus, Ibn al-Baitar, Carl Linnaeus, Gregor Johann Mendel, and Norman Borlaug.

History

Early botany

The history of botany begins with ancient writings on, and classifications of, plants. Such writings are found in several early cultures. Examples of early botanical works have been found in Ancient Indian sacred texts, ancient Zoroastrian writings, and ancient Chinese works.

Theophrastus (c. 371-287 BC) has been frequently referred to as the ”father of botany”. The Greco-Roman world produced a number of botanical works including Theophrastus's Historia Plantarum and Dioscorides' De Materia Medica from the first century.

Works from the medieval Muslim world included Ibn Wahshiyya's Nabatean Agriculture, Abы ?anоfa Dоnawarо's (828-896) the Book of Plants, and Ibn Bassal's The Classification of Soils. In the early 13th century, Abu al-Abbas al-Nabati, and Ibn al-Baitar (d. 1248) also wrote on botany.

Early modern botany

German physician Leonhart Fuchs (1501-1566) was one of "the three founding fathers of botany", along with Otto Brunfels (1489-1534) and Hieronymus Bock (1498-1554) (also called Hieronymus Tragus).

Valerius Cordus (1515-1544) authored a pharmacopoeia of lasting importance, the Dispensatorium in 1546.[12] Conrad von Gesner (1516-1565) and Nicholas Culpeper (1616-1654) also published herbals covering the medicinal uses of plants. Ulisse Aldrovandi (1522-1605) was considered the "father of natural history", which included the study of plants. In 1665, using an early microscope, Robert Hooke discovered cells, a term he coined, in cork, and a short time later in living plant tissue.

During the 18th century, systems of classification were developed that are comparable to diagnostic keys, where taxa are artificially grouped in pairs. The sequence of the taxa in keys is often unrelated to their natural or phyletic groupings. By the 18th century an increasing number of new plants had arrived in Europe from newly discovered countries and the European colonies worldwide and a larger amount of plants became available for study. Botanical guides from this time were sparsely illustrated. In 1754 Carl von Linnй (Carl Linnaeus) divided the plant Kingdom into 25 classes with a taxonomy with a standardized binomial naming system for animal and plant species. He used a two-part naming scheme where the first name represented the genus and the second the species. One of Linnaeus' classifications, the Cryptogamia, included all plants with concealed reproductive parts (mosses, liverworts and ferns), and algae and fungi.

The increased knowledge of anatomy, morphology and life cycles, lead to the realization that there were more natural affinities between plants, than the sexual system of Linnaeus indicated. Adanson (1763), de Jussieu (1789), and Candolle (1819) all proposed various alternative natural systems that were widely followed. The ideas of natural selection as a mechanism for evolution required adaptations to the Candollean system, which started the studies on evolutionary relationships and phylogenetic classifications of plants.

Botany was greatly stimulated by the appearance of the first "modern" text book, Matthias Schleiden's Grundzuge der Wissenschaftlichen, published in English in 1849 as Principles of Scientific Botany. Carl Willdenow examined the connection between seed dispersal and distribution, the nature of plant associations, and the impact of geological history. The cell nucleus was discovered by Robert Brown in 1831.

Modern botany

A considerable amount of new knowledge today is being generated from studying model plants like Arabidopsis thaliana. This weedy species in the mustard family was one of the first plants to have its genome sequenced. The sequencing of the rice (Oryza sativa) genome, its relatively small genome, and a large international research community have made rice an important cereal/grass/monocot model. Another grass species, Brachypodium distachyon is also an experimental model for understanding genetic, cellular and molecular biology. Other commercially important staple foods like wheat, maize, barley, rye, pearl millet and soybean are also having their genomes sequenced. Some of these are challenging to sequence because they have more than two haploid (n) sets of chromosomes, a condition known as polyploidy, common in the plant kingdom. A green alga, Chlamydomonas reinhardtii, is model organism that has proven important in advancing knowledge of cell biology.

In 1998 the Angiosperm Phylogeny Group published a phylogeny of flowering plants based on an analysis of DNA sequences from most families of flowering plants. As a result of this work, major questions such as which families represent the earliest branches in the genealogy of angiosperms are now understood. Investigating how plant species are related to each other allows botanists to better understand the process of evolution in plants. Despite the study of model plants and DNA, there is continual ongoing work and discussion among taxonomists about how best to classify plants into various taxa.

Scope and importance of botany

Molecular, genetic and biochemical level through organelles, cells, tissues, organs, individuals, plant populations, and communities of plants are all aspects of plant life that are studied. At each of these levels a botanist might be concerned with the classification (taxonomy), structure (anatomy and morphology), or function (physiology) of plant life.

Historically all living things were grouped as animals or plants, and botany covered all organisms not considered animals. Some organisms included in the field of botany are no longer considered to belong to the plant (plantae) kingdom, which obtain their energy via photosynthesis, - these include bacteria (studied in bacteriology), fungi (mycology) including lichen-forming fungi (lichenology), non-chlorophyte algae (phycology) and viruses (virology). However, attention is still given to these groups by botanists, and fungi (including lichens), and photosynthetic protists are usually covered in introductory botany courses.

The study of plants is vital because they are a fundamental part of life on Earth, which generates the oxygen, food, fibres, fuel and medicine that allow humans and other life forms to exist. Through photosynthesis, plants absorb carbon dioxide, a greenhouse gas that in large amounts can affect global climate. Just as importantly for us, plants release oxygen into the atmosphere during photosynthesis. Additionally, they prevent soil erosion and are influential in the water cycle.Plants are crucial to the future of human society as they provide food, oxygen, beauty, medicine, habitat for animals, products for people, and create and preserve soil.

Paleobotanists study ancient plants in the fossil record. It is believed that early in the Earth's history, the evolution of photosynthetic plants altered the global atmosphere of the earth, changing the ancient atmosphere by oxidation.

Human nutrition

Virtually all foods come either directly from plants, or indirectly from animals that eat plants. Plants are the fundamental base of nearly all food chains because they use the energy from the sun and nutrients from the soil and atmosphere, converting them into a form that can be consumed and utilized by animals; this is what ecologists call the first trophic level. Botanists also study how plants produce food we can eat and how to increase yields and therefore their work is important in mankind's ability to feed the world and provide food security for future generations, for example, through plant breeding. Botanists also study weeds, plants which are considered to be a nuisance in a particular location. Weeds are a considerable problem in agriculture, and botany provides some of the basic science used to understand how to minimize 'weed' impact in agriculture and native ecosystems. Ethnobotany is the study of the relationships between plants and people, and when this kind of study is turned to the investigation of plant-people relationships in past times, it is referred to as archaeobotany or paleoethnobotany.

Fundamental life processes.

Botanical research has long had relevance to the understanding of fundamental biological processes other than just botany. Fundamental life processes such as cell division and protein synthesis can be studied using plants without the moral issues that come with conducting studies upon animals or humans. Gregor Mendel discovered the genetic laws of inheritance in this fashion by studying Pisum sativum (pea) inherited traits such as shape. What Mendel learned from studying plants has had far reaching benefits outside of botany. Similarly, 'jumping genes' were discovered by Barbara McClintock while she was studying maize.

Medicine and materials

Many medicinal and recreational drugs, like tetrahydrocannabinol, caffeine, and nicotine come directly from the plant kingdom. Others are simple derivatives of botanical natural products; for example, aspirin is based on the pain killer salicylic acid which originally came from the bark of willow trees. As well, the narcotic analgesics such as morphine are derived from the opium poppy. There may be many novel cures for diseases provided by plants, waiting to be discovered. Popular stimulants like coffee, chocolate, tobacco, and tea also come from plants. Most alcoholic beverages come from fermenting plants such as barley (beer), rice (sake) and grapes (wine).

Hemp, cotton, wood, paper, linen, vegetable oils, some types of rope, and rubber are examples of materials made from plants. Silk can only be made by using the mulberry plant. Sugarcane, rapeseed, soy are some of the plants with a highly fermentable sugar or oil content which have recently been put to use as sources of biofuels, which are important alternatives to fossil fuels (see biodiesel).

Environmental changes

In many different ways, plants can act a little like the 'miners' canary', an early warning system alerting us to important changes in our environment. Plants respond to and provide understanding of changes in on the environment:

* Plant systematics and taxonomy are essential to understanding habitat destruction and species extinction.

* ultraviolet radiation causes changes in plants which help in studying problems like ozone depletion.

* Analyzing pollen from by plants thousands or millions of years ago allows reconstruct of past climates and predicting future ones; which is essential to climate change research.

* Study of plant life cycles is an important part of phenology, which is used in climate-change research.

Research

Ecology

The biology of a population is greater than the collective biologies of its individuals. Multiple members of the same species in close proximity constitute a population. Different populations in proximity constitute a community, which in conjunction with its nonliving environment constitute an ecosystem. The relation of each organism to all other organisms and factors in its habitat and environment make up its ecology. This includes structure, genetics and mutations, metabolism, diversity, fitness, adaptation, climate, water, and soil condition. The conditions that constitute an organisms life cycle is its habitat. Both negative and beneficial interactions with other organisms are parts of a plant's ecology. Herbivores eat plants, but plants can also defend against them. Some other organisms form beneficial relationships with plants, called mutualisms, for example with mycorrhizal fungi that provide nutrients, and honey bees that pollinate flowers. A biome is a large part of the earth that has very similar abiotic and biotic factors, climate, and geography, creating a typical ecosystem over that area that is characterized by its dominant plants. Examples include tundra and tropical rainforest.

Evolution

DNA provides the information for a plant's structure, metabolism, and biology. Genetics is the science of inheritance and the gene is its chemical basis. The same basic laws of genetics apply to both plants and animals. In sexual reproduction, offspring are often more fit than either parent since the stronger genes tend to be passed on to the next generation.[46] Mutations and natural selection result in a species acquiring new traits and eventually evolving into one or more new species. Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. Changes can also be caused by natural events such as a large meteor hitting Earth and selective breeding (artificial selection) of plants by humans for specific traits.

Since the mid-20th century, there has been considerable debate over how the earliest forms of life evolved and how to classify them, especially at the kingdom and domain levels and organisms that are or have been considered bacteria. For example, the three-domain method separates Archaea and Bacteria, previously grouped into the single kingdom Monera (bacteria). In this system Eukaryota (nuclei-bearing eukaryotes). Archaea was separated because it was shown to have a completely separate evolutionary history. However, Thomas Cavalier-Smith rejects the three-domain system and places the Archea as a subkingdom of Bacteria. Cyanobacteria were once believed to be related to algae and hence studied by botanists. Even now they are studied by both botanists and bacteriologists. Similarly, the Fungi (or Myceteae) were once considered plants but there is now uncertainty about how to classify them.

The various divisions of algae are also taxonomically problematic as some are more clearly linked to plants than others. Their many differences in features such as biochemistry, pigmentation, and nutrient reserves show that they diverged very early in evolutionary time. The division Chlorophyta (green algae) is considered the ancestor of true plants.

Nonvascular plants are embryophytes that do not have vascular tissue: mosses, liverworts, and hornworts. Many plants that are called "moss" actually are not. For example, Spanish moss (Tillandsia usneoides) is actually in the Bromeliaceae (pineapple) family. Nonvascular plants do not have xylem nor phloem. After the development of xylem and phloem, vascualar plants developed along two lines: Cryptogams (non seed producing), which developed first, and spermatophytes (seed producing). Spermatophytes are plants that produce seeds. Gymnosperms produce unenclosed seeds. Gymnosperms are the ancestors of Angiosperms, which produce a seed encased in a structure such as a carpel.

Physiology

Plant physiology is the energy the plant brings in acting upon materials brought into the plant via various mechanisms. Sunlight, either through photosynthesis or cellular respiration, is the basis of all life. Photoautotrophs gather energy directly from sunlight. This includes all green plants, cyanobacteria and other bacteria that can photosynthesize. Heterotrophs take in organic molecules and respire them. This includes all animals, all fungi, all completely parasitic plants, and non-photosynthetic bacteria. Respiration is the oxidation of carbon whereby it is broken down into simpler structures; essentially the opposite of photosynthesis.

Transport processes are those by which molecules are moved within the organism, such as: membranes transporting material across themselves and enzymess moving electrons. This is how minerals and water get from roots to other parts of the plant. Diffusion, osmosis, and active transport are different ways transport can occur. Examples of minerals that plants need are: nitrogen, phosphorous, phosphate, calcium, magnesium, and sulphur. Chemicals from the air, soil, and water in combination with sunlight form the basis of plant metabolism. Most of these elements come from minerals in a process called mineral nutrition. Few plants live in stable unchanging environments. Most plants most adapt to a variety of environmental factors, including changes in temperature, light and moisture. The better a plant can cope with these changing conditions, the more likely it can survive over both the short and long term as well as a wider geographic range. Cell types are unique and their nucleus stores most of the DNA.

Structure

Plant anatomy is the study of the internal cells and tissues of a plant; whereas plant morphology is the study of their general and external form.

Understanding the structure and function of cells is fundamental to all of the biological sciences. All organisms have cells. Cell biology studies their structural and physiological properties. This includes responses to stimuli, reproduction, and development on the macroscopic scale, microscopic scale, and molecular level. The similarities and differences between the function of a cell are quite varied. Plant cells are eukaryotic, ie, have a membrane-encased nucleus that carries genetic material. With rare exceptions, plant cells also have a central vacuole, cytoplasm, cytosol, dictyosomes, endoplasmic reticulum, microbodies, microfilaments, microtubules, mitochondria, plasma membrane, plastids, protoplasm, ribosomes, storage products, and a cell wall. Cells divide by processes known as karyokinesis and cytokinesis.

The body of a plant contains three basic parts: roots, stems, and leaves. Roots anchor it to the ground, gather water and mineral nutrients from the soil, and produce hormones. Plants with horizontal-spreading roots, such as willows, produce shoots and those with fleshy taproots, such as beets and carrots, store carbohydrates. Stems provide support to the leaves and store nutrients. Leaves gather sunlight and begin photosynthesis. Large, flat, flexible, green leaves are called foliage leaves. Gymnosperms are seed-producing plants which have open seeds, such as conifers, cycads, Gingko, and gnetophyta. Angiosperms are seed-producing plants that produce flowers, having enclosed seeds. Some of the gymnosperms became the ancestors of the angiosperms. Woody plants, such as azaleas and oaks, undergo a secondary growth phase resulting in two additional types of tissues: wood (secondary xylem) and bark (secondary phloem and cork). All gymnosperms and many angiosperms are woody plants. Some plants reproduce sexually, some asexually, and some via both means.

Systematics.

Scientific classification in botany is a method by which botanists group and categorize organisms by biological type, such as genus or species. Biological classification is a form of scientific taxonomy. Modern taxonomy is rooted in the work of Carolus Linnaeus, who grouped species according to shared physical characteristics. These groupings have since been revised to improve consistency with the Darwinian principle of common descent. While scientists do not always agree on how to classify organisms, molecular phylogenetics, which uses DNA sequences as data, has driven many recent revisions along more efficient, evolutionary lines and is likely to continue to do so. Botanical classification belongs to the science of plant systematics. The dominant classification system is called the Linnaean taxonomy. It includes ranks and binomial nomenclature. The classification, taxonomy, and nomenclature of botanical organisms is administered by the International Code of Nomenclature for algae, fungi, and plants (ICN).

The five-kingdom system has largely been superseded by modern alternative classification systems. Textbooks generally begin with the three-domain system: Archaea (originally Archaebacteria); Bacteria (originally Eubacteria); Eukaryota (including protists, fungi, plants, and animals). These domains reflect whether the cells have nuclei or not, as well as differences in the chemical composition of the cell exteriors and ribosomes.

Further, each kingdom is broken down recursively until each species is separately classified. The order is: Domain; Kingdom; Phylum; Class; Order; Family; Genus; Species. The scientific name of an organism is generated from its genus and species, resulting in a single world-wide name for each organism. For example, the Tiger Lily is listed as Lilium columbianum. Lilium is the genus, and columbianum the specific epithet. When writing the scientific name of an organism, it is proper to capitalize the first letter in the genus and put all of the specific epithet in lowercase. Additionally, the entire term is ordinarily italicized or underlined. Phylogenetics is the study of similarities among different species.

Agronomy.

Agronomy is the science and technology of producing and using plants for food, fuel, feed, fiber, and reclamation. Agronomy encompasses work in the areas of plant genetics, plant physiology, meteorology, and soil science. Agronomy is the application of a combination of sciences like biology, chemistry, economics, ecology, earth science, and genetics. Agronomists today are involved with many issues including producing food, creating healthier food, managing environmental impact of agriculture, and creating energy from plants. Agronomists often specialize in areas such as crop rotation, irrigation and drainage, plant breeding, plant physiology, soil classification, soil fertility, weed control, insect and pest control.

Plant breeding

This area of agronomy involves selective breeding of plants to produce the best crops under various conditions. Plant breeding has increased crop yields and has improved the nutritional value of numerous crops, including corn, soybeans, and wheat. It has also led to the development of new types of plants. For example, a hybrid grain called triticale was produced by crossbreeding rye and wheat. Triticale contains more usable protein than does either rye or wheat. Agronomy has also been instrumental in fruit and vegetable production research. It is understood that the role of agronomist includes seeing whether produce from a field of 'x' meets the following conditions: 1. Land and water access, 2. Commercialization (market), 3. Quality and quantity of inputs, 4. Risk protection (insurance), 5. Agricultural credit.

Biotechnology

Agronomists use biotechnology to extend and expedite the development of desired characteristics listed in the Plant Breeding section. Biotechnology is often a lab activity requiring field testing of the new crop varieties that are developed.

In addition to increasing crop yields agronomic biotechnology is increasingly being applied for novel uses other than food. For example, oilseed is at present used mainly for margarine and other food oils, but it can be modified to produce fatty acids for detergents, substitute fuels and petrochemicals.

Soil science

Agronomists study sustainable ways to make soils more productive and profitable. They classify soils and reproduce them to determine whether they contain substances vital to plant growth such as compounds of nitrogen, phosphorus, and potassium. If a certain soil is deficient in these substances, fertilizers may provide them. Soil science also involves investigation of the movement of nutrients through the soil, the amount of nutrients absorbed by a plant's roots, and the development of roots and their relation to the soil.

Soil conservation

In addition, agronomists develop methods to preserve the soil and to decrease the effects of erosion by wind and water. For example, a technique called contour plowing may be used to prevent soil erosion and conserve rainfall. Researchers in agronomy also seek ways to use the soil more effectively in solving other problems. Such problems include the disposal of human and animal wastes; water pollution; and also the build-up in the soil of pesticides. No-tilling crops is a technique now used to help prevent erosion. Planting of soil binding grasses along contours can be tried in steep slopes. For better effect, contour drains of depths up to 1 metre may help retain the soil and prevent permanent wash off.

Agronomy schools

Agronomy programs are offered at colleges, universities, and specialized agricultural schools. Agronomy programs often involve classes across a range of departments including agriculture, biology, chemistry, and physiology. They can usually take from four to twelve years. Many companies will pay an agronomist-in-training's way through college if they agree to work for them when they graduate.

Career outlook

Due to the continued growth of the global population--and the consequent expanding need for study of food crops and agriculture in general--the outlook for agronomy and agronomists is excellent. Past agricultural research has created higher yielding crops, crops with better resistance to pests and plant pathogens, and more effective fertilizers and pesticides. Research is still necessary, however, particularly as insects and diseases continue to adapt to pesticides and as soil fertility and water quality continue to need improvement.

Emerging biotechnologies will play an ever larger role in agricultural research. Scientists will be needed to apply these technologies to the creation of new food products and other advances. Moreover, increasing demand is expected for biofuels and other agricultural products used in industrial processes. Agricultural scientists will be needed to find ways to increase the output of crops used in these products.

Agronomists will also be needed to balance increased agricultural output with protection and preservation of soil, water, and ecosystems. They increasingly encourage the practice of sustainable agriculture by developing and implementing plans to manage pests, crops, soil fertility and erosion, and animal waste in ways that reduce the use of harmful chemicals and do little damage to farms and the natural environment.

Most agronomists are consultants, researchers, or teachers. Many work for agricultural experiment stations, federal or state government agencies, industrial firms, or universities. Agronomists also serve in such international organizations as the Agency for International Development, The United States Department of Agriculture, and the Food and Agriculture Organization of the United Nations.

Agronomists career options are expanding rapidly with possible ties with golf landscaping including topsoil analysis and drainage conditions. They often work in conjunction with landscape architects and engineers to determine the best soil qualities/conditions to suit the site specifications.

Vegetable farming.

Vegetable farming is the growing of vegetables for human consumption.

Traditionally it was done in the soil in small rows or blocks, often primarily for consumption on the farm, with the excess sold in nearby towns. Later, farms on the edge of large communities could specialize in vegetable production, with the short distance allowing the farmer to get his produce to market while still fresh. The three sisters method used by Native Americans (specifically the Haudenosaunee/Iroquois) grew squash, beans and corn together so that the plants enhanced each other's growth. Planting in long rows allows machinery to cultivate the fields, increasing efficiency and output; however, the diversity of vegetable crops requires a number of techniques to be used to optimize the growth of each type of plant. Some farms, therefore, specialize in one vegetable; others grow a large variety. Due to the needs to market vegetables while fresh, vegetable gardening has high labor demands. Some farms avoid this by running u-pick operations where the customers pick their own produce. The development of ripening technologies and refrigeration has reduced the problems with getting produce to market in good condition.

Over the past 100 years a new technique has emerged--raised bed gardening, which has increased yields from small plots of soil without the need for commercial, energy-intensive fertilizers. Modern hydroponic farming produces very high yields in greenhouses without using any soil.

Several economic models exist for vegetable farms: farms may grow large quantities of a few vegetables and sell them in bulk to major markets or middlemen, which requires large growing operations; farms may produce for local customers, which requires a larger distribution effort; farms may produce a variety of vegetables for sale through on-farm stalls, local farmer's markets, u-pick operations. This is quite different from commodity farm products like wheat and maize which do not have the ripeness problems and are sold off in bulk to the local granary. Large cities often have a central produce market which handles vegetables in a commodity-like manner, and manages distribution to most supermarkets and restaurants.

In America, vegetable farms are in some regions known as truck farms; "truck" is a noun for which its more common meaning overshadows its historically separate use as a term for "vegetables grown for market". Such farms are sometimes called muck farms, after the dark black soil in which vegetables grow well.

Размещено на Allbest.ru