Plant breeding is the science of modifying the characteristics of plants to produce desired characteristics.[1] It has been used to improve the nutritional quality of products for humans and animals.[2] The goals of plant breeding are to produce plant varieties with unique and superior characteristics for a variety of agricultural applications. The most frequently addressed traits are those linked to tolerance to biotic and abiotic stresses, grain or biomass yield, end-use quality characteristics such as taste or concentrations of specific biological molecules (proteins, sugars). , lipids, vitamins, fibers) and ease of processing. (harvesting, milling, cooking, malting, mixing, etc.).[3]

Plant breeding can be carried out using many different techniques, from simple selection of plants with desirable traits for propagation, to methods using knowledge of genetics and chromosomes, to more complex molecular techniques (see cultigen and cultivar). A plant's genes determine the type of qualitative or quantitative traits it will have. Plant breeders strive to create a specific result of plants and potentially new plant varieties and, in doing so, restrict the genetic diversity of that variety to a few specific biotypes.

It is practiced worldwide by individuals such as gardeners and farmers, as well as professional plant breeders employed by organizations such as government institutions, universities, crop-specific industry associations, or research centers. research.

International development agencies believe that breeding new crops is important to ensure food security by developing new varieties that are higher yielding, disease resistant, drought resistant or regionally adapted to different environments and growing conditions.

History

History of plant breeding
Plant breeding began with sedentary agriculture and in particular with the domestication of the first agricultural plants, a practice that dates back 9,000 to 11,000 years. Initially, early farmers simply selected food plants with particularly desirable traits and used them as broodstock for subsequent generations. resulting in an accumulation of valuable traits over time.

Grafting technology was practiced in China before 2000 BCE.

By 500 BCE, grafting was well established and practiced.

Gregor Mendel (1822-1884) is considered the “father of genetics”. His experiments with plant hybridization led him to establish inheritance laws. Genetics has stimulated research to improve agricultural production through plant breeding.

Modern plant breeding falls under applied genetics, but its scientific basis is broader and covers molecular biology, cytology, systematics, physiology, pathology, entomology, chemistry and statistics (biometrics). It has also developed its own technology.

A major plant breeding technique is selection, the process of selectively propagating plants with desirable characteristics and eliminating or "eliminating" those with less desirable characteristics.

Another technique is the deliberate crossing of closely or distantly related individuals to produce new crop varieties or lines with desirable properties. Plants are crossed to introduce traits/genes from one variety or lineage into a new genetic background. For example, a downy mildew resistant pea can be crossed with a high yielding but susceptible pea, the aim of the cross being to introduce resistance to downy mildew without losing the high yielding characteristics. The offspring from the cross would then be crossed with the high-yielding parent to ensure that the offspring most closely resemble the high-yielding parent (backcross). The progeny from this cross would then be tested for yield (selection, as described above) and resistance to downy mildew and high-yielding resistant plants would be developed further. Plants can also be crossed with each other to produce inbred varieties for breeding. Pollinators can be excluded through the use of pollination bags.

Classical breeding relies largely on homologous recombination between chromosomes to generate genetic diversity. The conventional plant breeder can also use a number of in vitro techniques such as protoplast fusion, embryo rescue or mutagenesis to generate diversity and produce hybrid plants that would not exist in nature.

Traits that breeders have tried to incorporate into cultivated plants include:

Improved quality, such as increased nutrition, improved flavor, or greater beauty
Increased harvest yield
Increased tolerance to environmental pressures (salinity, extreme temperatures, drought)
Resistance to viruses, fungi and bacteria
Increased tolerance to harmful insects
Increased tolerance to herbicides
Longer storage period for harvested crop

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