1. 15.2 Plants in Agriculture By : James Quach

2. Food Plants  Plants are either eaten directly or indirectly either from animals that feed on grain or grass, or through fruits and vegetables  Edible parts of plants can be put into 3 categories:  Parts that grown underground (Ex. Potatoes and Carrots)  Parts that grow above ground (Ex. Lettuce)  The seeds and fruits of plants (Ex. Tomatoes, Apples, etc)  Grain provides the most food supply in the world that includes rice, wheat, corn, oats and barley.  Group of plants that specialize in fruit-producing are called legumes, the major source of food and the second most important group of food- producing plants.  Many types of peas and beans are found in this group that includes soybeans, peanuts, and lentils.

3.  Plants can be processed into a variety of different food products that exist today such as wheat seeds grounded into flour, to which is made into bread or soybeans are processed to make tofu, soy sauce, soy milk or vegetable proteins.  Many plants serve different purposes for different food products and adding a combination might lead to new food products which may exist today.

4. Increasing Plant Productivity  Growers that select individual plants based on their desirable trait and use them to breed and produce offspring with those traits, resulting in new species is called selective breeding.  This process has been tested with many plant species that has lead to increase crop yield and enhanced disease resistance.  Another process that plant breeders use to take advantage of different characteristics of the same or similar plant species is known as hybridization which the “daughter” plants inherits both the “parent” varieties’ characteristics when they are grown from the resulting seeds.  Some plant species can grow into entirely new plants just through a single leaf of the parent plant which is identified as cloning.  In cloning, there are two methods to choose from which are cuttings and grafting.

5.  Cuttings is the first, far-most simplest method to cloning which involves cutting off a piece of the plant that includes a stem and eventually a clump of tissue will develop at the end of the cut called callus, by which roots will form and soon grow exactly identical to the parent plant.  The other method is grafting which can only work on certain plants that contain a special tissue called cambium.  Grafting starts off with a bud from a plant with certain desired characteristics is grafted or attached onto a rooted stem or root of another plant, that contains other wanted features. The shoot is called the scion, while the root is called the stock.  At the graft site, the cambium of the stock and the cambium of the scion will eventually merge into one resulting a “new” plant that can contain thousands of genetically identical copies.  Apples, plums, grapes and peaches are commonly produced by grafting  Now today, grafting is easier to perform with the help of technology just by small pieces of tissue or single cells growing in test tubes. Test tubes contain a growth medium that has nutrients and hormones to speed up the growth process and differentiate into seedlings and transferring it to soil.

7. Control of Agricultural Pests  There are many ways of controlling agricultural pests and here are some:  Chemical control: Agricultural pesticides are chemicals that eliminate organisms that eat, infect or compete with crops. Each type of pesticide kills certain organism, and has saved many crops due to these chemicals. These pesticides may cause health and environmental problems, and are very expensive to maintain as farmers spend about $750 million year on them.  Biological control: Anything that involves with the use of natural parasites or predators to control or eliminate agricultural pests and also to keep them away from crops too. Farmers may grow certain plants that may contain toxin or bad taste to the insects to prevent them from destroying crops nearby. This method reduces the amount of chemical pesticides needed, but requires a lot of knowledge of which parasite or predator should be used against the agricultural pests, as it can backfire as well.

8.  Food irradiation: Technology that is used to preserve food. Fruits, vegetables and grains are examples of food that are selected for measure doses of radiation to kill of any harmful pests, fungi and bacteria. Many benefits are gain from irradiation as it slows the ripening of certain fruits and vegetables and fruits, therefore expanding their storage life. Also the preserved food are expose to radioactive cobalt and cesium which emits out immense energized particles that kill off pests that are living off in or on the food. This process has been used mainly on wheat flour, ground spices, potatoes and onions in Canada.

9. Genetically Modified (GM) Plants  Plants that have been modified through selective breeding or hybridization have different genes with desire characteristics produced. Now with recombinant DNA, other plant species and even animal species can be added to produce a newly modified plant called a transgenic plant or as a genetically modified (GM) plant due to the genes it contains from completely different species.  Bacteria is often introduced in this process, and is mainly useful for gaining further desired characteristics such as insect-resistant and these GM plants are always tested to ensure safety and no adverse effects to humans when eaten; however, long-term possible effects are unknown.  Main purpose of GM plants are so that it will increase crop yields to meet the standard nutritional demands of a steadily growing population. Many GM plants get enhanced and modified either to gain improved nutritional content, drought- and salt-resistant, etc.

11. Preserving Old Plant Varieties  When a plant has developed with the desirable characteristics, it is commonly grown in large numbers. Cultivation of a crop in a large area is known as monoculture. Though growing the same variety does provide benefits, it can also have drawbacks such as unable to resist a certain bacterial or fungal disease. In this case, the entire crop may be wiped out clean.  Anywhere around the world, agricultural seeds of all varieties are stored in seed banks, including wild and cultivated varieties. There are several reasons the seed banks are important:  Firstly, the genes of a large number of varieties of an agricultural plant must be saved in case of disasters that can occur and are available to be used after the disaster.  Secondly, when new or stronger diseases intend to appear, wild relatives of crop plants often are good sources of resistance against them.

12.  Thirdly, if a plant variety were about to go into extinction, scientists may re- introduce the plant using the stored seeds.  Lastly, seed plants of that no longer are used in agriculture are available for research purposes. Improved varieties may develop from the stored seeds with the help of new technology.

13. Plant Technology Trade-offs  Many factors are considered when creating and using plant technologies. Some of the factors are:  The cost and development of the technology and is based on the price of the product.  The safety of developing a new plant technology that will affect everyone which may include health risks like nut allergies, overweighing the benefits in the process  Consumer preferences can determine what plant technology should be made and used for many types of reasons that include eco-friendly, cheapest food possible while maintaining its taste and looks good, prefer costly organic food, etc.

14. References  http://en.wikipedia.org/wiki/Plant http://en.wikipedia.org/wiki/Plant  http://www.epa.gov/agriculture/tipm.html http://www.epa.gov/agriculture/tipm.html  http://www.sciencedaily.com/articles/b/biological_pest_control.htm http://www.sciencedaily.com/articles/b/biological_pest_control.htm  http://www.physics.isu.edu/radinf/food.htm http://www.physics.isu.edu/radinf/food.htm  http://www.greenfacts.org/en/gmo/index.htm http://www.greenfacts.org/en/gmo/index.htm  Biology Grade 11 Addison Wesley Textbook

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