7/2/2015dma: chapter i hartmann's plant science, 4th edition 1 chapter i: history, trends,...

04/19/23 DMA: Chapter I Hartmann's Plant Science, 4th edition

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CHAPTER I: History, Trends, Issues, and

Challenges in Plant Science HISTORY• If we were to go back in time 150 million years, we would

see many plants very similar to those common in our century.

• During this time, humans had no influence on changes in life forms that occurred.

• 12,000 to 10,000 years ago (perhaps earlier according to recent archaeological finds) humans began


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Plant cultivation • Plant cultivation: The purposeful growing or cultivation

of plants to improve the supply of materials obtained from these plants.

• is believed to have started in areas tropical and subtropical regions in the Middle East and Africa. (By cultivating plants, humans reduced the need to travel to follow the food supply).

Agronomy is the study of field-grown crops such as wheat, soybeans, corn, forages, and those used for industrial purposes that require relatively low input during the growing part of their life cycle.

Horticulture is the study of crops include most fruits, vegetables, and ornamentals that require more intense and constant care, from planting through delivery to the consumer.


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TRENDS AND ISSUES AFFECTING PLANT SCIENCE

• Photosynthesis is the underlying process that makes all life on earth dependent on all plants, not just the cultivated ones.

Embodied Energy:

is the sum of all the

energy required

to produce any goods

or services, considered

as if that energy was

incorporated or

'embodied' in the

product itself.


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Domestic Trends and Issues: give dull

view about green coverage • Even though yields continued to increase,

income per acre declined (Fig. 1-2)


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The number of farm workers also continued its

long-term decline (Fig. 1-3).


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The area of farmland has also declined (Fig. l-4).


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Global Trends and Issues • Two major trends that will affect crop production and the global

environment are:

– The increases in human population: → more production– The increases in energy use.

• After two centuries of exponential growth, world population shows signs of stabilizing at about 9 billion in 2050 (Fig. 1-5). النسل تنظيم


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Energy use is projected to rise about twice as fast as population because of economic development=

export (Fig. 1-6).


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Example:

• China alone represents a major challenge to the world's food supply. It has about 20 percent of the world's population but less than 7 percent of the world's cropland. It had about 0.2 hectares per person in 1950 and now has about 0.08. ==== import


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Research • For several centuries, plant scientists studied ways to

improve crop productivity in a cost-effective way: بطريقةالتكلفة حيث من فعالة

1. They studied abiotic factors: light, soil, water, and temperature and developed ways of managing or monitoring those factors to influence or predict plant growth. As Glass houses, improve soil characters and water use eff.

2. They studied biotic factors: herbs, virus, and pests and their management reduced losses to those factors. Control of factors.

3. Improved understanding of plant genetics lead to breeders developing plants that surely would produce more.Modern Plant biotechnology. Genetically modified organisms (GMOs). Changes in DNA structure


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Organic farming

• Organic farming has been proposed as a solution to many problems related to crop production and environmen tal impact.

• Organic farming does not allow the use of GMOs

and certain types of chemicals for pest control and fertilization.

• However, it is not known if organic farming has the capability to produce the quantities of crop products needed in today's world.


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Perfect plant and dependency

• Maintaining perfect plants almost certainly has some degree of negative environmental impact.

• Although most plants grow very well without human intervention, the cultivated grains and grasses, fruits, vegetables, and orna mentals have become dependent on human intervention to survive. Without cultivation, these plants would die out after several generations and be replaced by hardier species such as wild grasses and thistles: الشوكية


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Cultivated plants are:

Over half the world's food supply comes from the photosynthetic activity of cereal crops.

1. Cereal crops Wheat, maize (corn), rice, barley, oats, sorghum, ryeجاوادار, and millet دخن . (Over half the world's food supply comes from the photosynthetic activity of these crops.)

2. Roots and tubers

Potatoes, sweet potatoes, and cassavas.

3. Oil crops Soybeans, corn, peanuts سوداني ,فولpalm,coconuts هند ,sunflowers, olive ,جوزand safflower.

4. Sugar Sugar cane and sugar beets.

5. Fruit crops Bananas, oranges, apples, pears, and many others.

6. Vegetable crops

Tomatoes, lettuce, carrots, melons, asparagus, and so for


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Not all of the total production of food materials becomes available for human consumption

1. Much is lost during harvesting, transportation, and marketing, primarily from attacks by insects, diseases, birds, and rodents.

2. Some of the production is saved to be used as seed for future plantings.

3. Some plants are used to produce human food in the form of animal products.


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3. Some plants are used to produce human

food in the form of animal products – Loss: Energy loss. For example, it takes about 10

kilograms of grain (which could be consumed by humans directly) to produce 1 kilogram of beef.

– Gain: Some of the kinds of feed consumed by animal is ordinarily not eaten by humans.

– Gain: Meat, milk, and eggs are important in the human diet because they contain proteins of the proper quality, as well as some of the necessary minerals and vitamins.


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TABLE 1 Some Important Food Crops Ranked According

to Calorie and Protein Production per Unit of Land Area Rank Calories Produced per Unit

AreaProtein Produced per Unit

Area

1 Sugar cane Soybeans

2 Potato Potato** short season +↑prod. /unit of area

3 Sugar beets Corn

4 Corn Peanuts

5 Rice Sorghum

6 Sorghum Peas

7 Sweet potato Beans

8 Barley Rice

9 Peanuts Barley

10 Winter wheat Winter wheat


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The requirements for continuing increases in the world's food-producing capability are of following conditions:1. The shift in food consumption patterns. processing2. The tremendous increase in world population,

especially in developing regions (see Fig. 1-7).

3. Much of the world's best agricultural land is already under cultivation, although there is still unused productive land awaiting develop ment in Argentina, Brazil, Canada, Sudan, and Australia.

4. Agricultural land losses for many reasons such as urban expansion and climate changes.


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Mid-1970s various projections

In the mid-1970s various projections implied that the world was on the brink of famine or ecological disasters due to desperate food needs. But this assessment changed in the 1980s by:

1. Improved production technology and greater

incentives to use it.

2. Agricultural research made new cultivars of high-yielding wheat, rice, corn, and other crops (Cultivar = cultivated variety.)


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MEETING THE CHALLENGES IN PLANT SCIENCE

Currently, enough food is produced to feed the world's population. However, malnutrition and starvation exist in both developed and undeveloped countries (mostly in the sub-Saharan regions of Africa) mostly because social and political issues prevent the distribution of food to those who need it.


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Social and political issues prevent the distribution of food to those who need it1. Drought2. Wars3. Political instability4. High human fertility rates5. Low per capita income الدخل من الفرد نصيب انخفاض6. Insufficient monetary investment in agricultural

production. 7. Poor distribution of available food since it is of costand

remain in the hands of rich countries.• Solution: Produce food crops locally in starvation-

prone areas.


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Meet today's challenges includes the ecological paradigmنموذج of agriculture in all scientific studies.

A model for this concept was developed that is built on four areas of focus:

• Production efficiency, • Economic viability, • Environmental

compatibilityمتوافق , • Social responsibility. [Fig.

1-8]


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BENEFITS FROM CULTIVATED PLANTS

Plants improve soil properties and prevent its erosion because:

1. Their decomposing roots, stems, and leaves add to the soil's mass, forming a humus material.

2. Their roots act as webs to hold the soil in place.

3. Their leaves and branches slow the force of the falling water.


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Wood and Wood Products from Timber Trees

1. Human shelter.

2. Source of fuel (Unlike coal, gas, and oil, wood is a renewable natural resource).

3. Construction and other utilitarian uses, such as home furnishings.

4. The ornamental value of trees used for landscape and other aesthetic purposes such as carvingنحت is nearly inestimable.

5. The biochemicals found in some wood species provide products for industry and medicine. Industrial products include latexمطاط, pitch مالعب .and resin ,فرش

6. The manufacture of paper.


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Textiles from Fiber-Producing Crops

1. Cotton, flaxكتان, and hemp فنب supply much of the fabric that clothe us and shelter us.

2. Cotton, hemp, and also jute are used to make string خيط , twineجدايل, rope, and burlapالخيش.

• Unfortunately, hemp grown for fiber is the same species as marijuana قنب Marijuana plants produce the drug .هنديtetrahydrocannabinol (THC).


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Drugs and Medicines

• From the earliest history of humans, man used herbs to treat diseases and disorders.

• Much of this wealthثروة of plant lore is in danger of being lost as indigenous cultures الثقافة .are absorbed into modem civilizationsاالصلية

• Ethanobotany, the study of plant usage by indigenous cultures and the preservation of that knowledge about plants.


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Examples:1. Salicylic acid, the pain-relieving component of aspirin, is found in

the bark of willowصفصاف trees (Salix). quinine, which is used to treat malaria, and the heart medication, digitalis. Morphine, opium codeine, and heroin are all pain-relieving extracts of the ,افيونopium poppy افيون .(Papaver somniferum)خشخاش

2. Cocaine, another painkiller, is derived from the coca plant (Erythroxylum coca). However, each of these pain-relieving drugs also has addic tive properties.

3. One of the newest plants to be recognized for its medicinal benefits is a yew الطقسوس that produces taxol, a chemical (Taxus)خشبthat shows promise in the treatment of cancer.

Plants also provide latex, pitch, waxes, essential oils, perfumes, species, and other products.


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Plants for Ornamental and Recreational

Purposes

1. The appearance and playability of fields is vitally important to many sports.

2. Residential and commercial landscaping is a business that generates billions of dollars annually in the United States alone.

7/2/2015dma: chapter i hartmann's plant science, 4th edition 1 chapter i: history, trends,...

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