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Conventional Plant Breeding Has Been Has Breeding Plant Conventional See still commonly used today. Early today. used commonly still domesticated plant species plant domesticated Breeding”.) going on for hundreds of years, and is and years, of hundreds for on going dramatically changed dramatically Conventional plant breeding has been has breeding plant Conventional see. (See box “Mutation box (See see. seeds, or sweeter fruits has fruits sweeter or seeds, traits that breeders would like to like would breeders that traits and disease resistance, larger resistance, disease and unreliable to produce all the plant the all produce to unreliable forearm. faster growth, higher yields, pest yields, higher growth, faster rate of mutation is very slow and slow very is mutation of rate which produce cobs as long as one’s as long as cobs produce which The selection for features such as such features for selection The but the natural the but , mutation called hundreds of varieties of corn, some of some corn, of varieties of hundreds spontaneously through a process a through spontaneously one’s little finger. Today, there are there Today, finger. little one’s improved varieties. improved farmers harvested were smaller than smaller were harvested farmers traits occasionally arise occasionally traits desirable traits to develop to traits desirable desirable traits. A few of these of few A traits. desirable corn cobs corn a plant to select for specific for select to plant a individual plants that exhibit that plants individual of different crops. This has This crops. different of years ago, the ago, years what they knew about the genes of genes the about knew they what travel long distances in search of search in distances long travel to create new and improved varieties improved and new create to thousands of thousands understood, plant breeders used breeders plant understood, Breeders scrutinize their fields and fields their scrutinize Breeders select superior plants and breed them breed and plants superior select America, genetics became better became genetics important in plant breeding. plant in important breeders understood better how to how better understood breeders South season. Then, once the science of science the once Then, season. future generations is very is generations future North and North developed in the 20th century, plant century, 20th the in developed saved them to plant for the next the for plant to them saved traits and incorporating them into them incorporating and traits grown in grown science of plant breeding was further was breeding plant of science best looking plants and seeds and seeds and plants looking best The art of recognizing desirable recognizing of art The combined in the offspring. When the When offspring. the in combined was first was grow. Early farmers selected the selected farmers Early grow. different parent plants could also be also could plants parent different when corn when genetic makeup of the crops they crops the of makeup genetic fiber. Desirable characteristics from characteristics Desirable example, farmers have been altering the altering been have farmers S plants we grow for food, feed and feed food, for grow we plants cross-pollinated to increase yields. increase to cross-pollinated relatives. For relatives. ten thousand years ago, years thousand ten productivity and quality of the of quality and productivity their wild their plants could be artificially mated or mated artificially be could plants agriculture began, eight to eight began, agriculture dramatically increased the increased dramatically compared to compared farmers discovered that some crop some that discovered farmers ince the practice of practice the ince References Pocket Ks are Pockets of Knowledge, Pocket Conclusion packaged information on crop Bauman, F. and Crane, P.L. 1992. Hybrid corn biotechnology products and related Conventional plant breeding - History, development and selection issues available at your fingertips. They considerations. National Corn Handbook. KK KKNo. 13 resulting in open pollinated are produced by the Global Knowledge varieties (OP) or hybrid varieties Purdue University, US. Center on Crop Biotechnology (http:// DANIDA. 2002. Assessment of potentials and www.isaaa.org/kc). For more has had a tremendous impact constraints for development and use of on agricultural productivity over information, please contact the plant biotechnology in relation to plant International Service for the Acquisition the last decades. While an breeding and crop production in developing of Agri-biotech Applications (ISAAA) extremely important tool, countries. Working paper. Ministry of SEAsiaCenter c/o IRRI, DAPO Box conventional plant breeding also Foreign Affairs, Denmark. 7777, Metro Manila, Philippines. has its limitations. First, East-West Seeds 1982-2002. 2002. Tel: +63-2 8450563 Conventional Plant breeding can only be done Vegetable Breeding for Market Fax: +63-2 8450606 between two plants that can Development. Edited by Karl Kunz. E-mail: [email protected] Bangkok, Thailand. Breeding sexually mate with each other. Food and Agriculture Organization. 2002. First Printing, March 2004 This limits the new traits that can Crop Biotechnology: A working paper for be added to those that already administrators and policy makers in Sub- exist in a particular species. Saharan Africa. Second, when plants are History of Plant Breeding (http:// crossed, many traits are www.colostate.edu/programs/lifesciences/ transferred along with the trait/s TransgenicCrops/history.html) of interest - including those traits Hybrid varieties and saving seed (http://aggie-horticulture.tamu.edu/ that have undesirable effects on INTERNATIONAL SERVICE plantanswers/vegetables/seed.html) FOR THE ACQUISITION Global Knowledge Center yield potential. International Rice Research Institute. (http:// OF AGRI-BIOTECH PPLICATIONS on Crop Biotechnology www.irri.org) A Hybrid seed technology The end result of plant breeding is either an This is the simplest form of hybridization, In the US, the of improved open-pollinated (OP) variety or an F1 (first but there are complications, of course. A widespread use plant filial generation) hybrid variety. OP varieties, completely pure line can sometimes take of corn hybrids, characteristics, when maintained and produced properly, seven or eight years to achieve. coupled with tropical retain the same characteristics when Sometimes, a pure line is made up of improved cultural vegetable multiplied. The only technique used with OP several previous crossings to build in practices by breeders can varieties is the selection of the seed- desirable features. The resulting plant is farmers, has more point to some bearing plants. then grown on until it is genetically pure than tripled corn rather clear achievements over the last two before use in hybridization. grain yields over decades: Hybrid seeds are an the past 50 years improvement over In addition to from an average • Yield improvement. Hybrids often open pollinated seeds qualities like of 35 bushels per outyield traditional OP selections by in terms of qualities good vigor, acre in the 1930s 50-100% due to its improved vigor, such as yield, trueness to to 115 bushels per acre in the 1990s. No improved genetic disease resistance, resistance to pests type, heavy other major crop anywhere in the world improved fruit setting under stress, and diseases, and yields and high even comes close to equaling that sort of and higher female/male flower ratios. time to maturity. Hybrid uniformity success story. seeds are developed which hybrid plants enjoy, other • Extended growing season. Hybrids by the hybridization or characteristics such as earliness, disease Hybrid rice technology helped China often mature up to 15 days earlier than crossing of parent lines that are ‘pure lines’ and insect resistance and good water increase its rice production from 140 million local OP varieties. For many crops, the produced through inbreeding. Pure lines are holding ability have been incorporated into tons in 1978 to 188 million tons in 1990. hybrid’s relative advantage over the plants that “breed true” or produce sexual most F1 hybrids. Research at the International Rice Research OP is most pronounced under stress offspring that closely resemble their Institute (IRRI) and in other countries conditions. parents. By crossing pure lines, a uniform Unfortunately, these advantages come with indicates that hybrid rice technology offers population of F1 hybrid seed can be a price. Because creating F1 hybrids opportunities for increasing rice varietal • Quality improvement. Hybrids have produced with predictable characteristics. involves many years of preparation to yields by 15-20%. And this is achievable helped stabilize product quality at a create pure lines that have to be constantly with the improved, semi-dwarf, and inbred higher, and more uniform level – this The simplest way to explain how to develop maintained so that F1 seeds can be varieties (IRRI). implies improved consumption quality an F1 hybrid is to take an example. Let us harvested each year, the seeds then (e.g. firm flesh of wax gourd, crispy say a plant breeder observes a particularly become more expensive. The problem is Many cultivars of popular vegetables or taste of watermelon). good habit in a plant, but with poor flower compounded because to ensure that no ornamental plants are F1 hybrids. In terms color, and in another plant of the same type self-pollination takes place, all the he sees good color but poor habit. The best hybridization of the two pure lines, plant of each type is then taken and self- sometimes, has to be done by hand. Mutation breeding pollinated (in isolation) each year and, each year, the seed is re-sown. Eventually, Another disadvantage is if the seeds of the In the late 1920s, researchers every time the seed is sown the same F1 hybrids are used for growing the next discovered that they could greatly identical plants will appear. When they do, crops, the resulting plants do not perform increase the number of these variations this is known as a ‘pure line.’ as well as the F1 material - resulting in or mutations by exposing plants to X- inferior yields and vigor.
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