Plant Breeding and Cultivar Development
- [Golden Rice Field - These rice plants have been genetically engineered to produce significantly higher amounts of β-carotene compared to normal rice, leading to their golden appearance. Since β-carotene is a precursor of vitamin A, this fortified rice can help prevent blindness and disease associated with diets low in vitamin A.]
- Overview
Plant breeders have made great strides in genetic enhancement of yield, adaptive traits, pest and disease resistance, abiotic stress tolerance, and nutritional and/or end-use quality, increasing crop yield and productivity (yield per unit area) of major crops.
With increasing population demands and increasing climate change, plant breeding is more important than ever to meet production challenges and ensure a steady supply of food, feed and fiber.
Recent research advances in the fields of biotechnology, genomics, and phenomics provide plant breeders with advanced tools for producing improved varieties.
- The Objectives and Scope of Plant Breeding
The overall objective of plant breeding is to improve the plant species. breeding objectives include higher yield, higher quality, greater vigor and persistence, resistance to pests, and greater tolerance of climatic and soil conditions.
Plant breeding, the application of genetic principles to produce plants that are more useful to humans. This is accomplished by selecting for economically or aesthetically pleasing plants, first by controlling the mating of selected individuals and then by selecting certain individuals among the offspring. Such processes, repeated over many generations, can alter the genetic makeup and value of plant populations far beyond the natural limits of pre-existing populations.
Plant breeding is the science of altering plant traits to produce desired traits. It has been used to improve the nutritional quality of human and animal products. The goal of plant breeding is to develop crop varieties with unique and superior traits, suitable for various applications.
The most frequently mentioned agricultural traits are related to biotic and abiotic stress tolerance, grain or biomass yield, end-use quality traits (e.g. taste or concentration of specific biomolecules (proteins, sugars, lipids, vitamins, fibres)) Characteristic processing related to ease of use (harvesting, milling, roasting, malting, blending, etc.).
- Plant Breeding Techniques
Plant breeding can be performed through many different techniques, ranging from simple selection of plants with desirable reproductive characteristics, to methods that exploit knowledge of genetics and chromosomes, to more complex molecular techniques.
The genes in a plant determine what type of qualitative or quantitative trait the plant will have. Plant breeders strive to create plants with specific fruits and potential new plant varieties, and in doing so, narrow the genetic diversity of that variety to a specific few biotypes. It is practiced worldwide by individuals such as gardeners and farmers, as well as professional plant breeders employed by organizations such as government agencies, universities, industry associations for specific crops, or research centers.
International development agencies believe that breeding new crops is important to ensure food security by developing new varieties with higher yields, disease resistance, drought tolerance or regional adaptation to different environmental and growing conditions.
A recent study shows that without plant breeding, arable crop yields in Europe would have been reduced by 20% over the past 20 years, consuming an additional 21.6 million hectares and emitting 4 billion tons of carbon. Wheat varieties created for Morocco are currently being crossed with plants to create new varieties for northern France. Soybeans, previously grown mainly in southern France, are now grown in southern Germany.
- [Holy Basil (Ocimum Tenuiflorum) - Denver Botanic Gardens]
- Cultivar Development
A cultivar is a cultivated plant that people select for desired traits and that retain those traits when propagated. Methods used to propagate cultivars include: divisions, rhizome cuttings, offsets, grafting, tissue culture, or carefully controlled seed production. Most varieties come from purposeful human manipulation, but some come from wild plants with unique characteristics. Cultivar names are chosen according to the rules of the International Code of Cultivated Plant Nomenclature (ICNCP), and not all cultivated plants qualify as cultivars. Horticulturalists generally agree that the word cultivar was coined as a term meaning "cultivated variety".
Popular ornamental plants, such as roses, camellias, daffodils, rhododendrons, and rhododendrons, are often produced through breeding and selection as cultivars, or as sporting varieties, for flower color or size, plant form, or other desirable characteristics. Likewise, the world's food crops are almost exclusively selected varieties for traits such as increased yield, flavor and disease resistance, and few wild plants are now used as food sources. Trees used in forestry are also special choices planted for wood quality and yield.
- Cultigen and Cultivar
Cultigen and cultivar may be confused with one another. Cultigen is a general-purpose term encompassing not only plants with cultivar names but others as well, while cultivar is a formal classification category.
A cultigen or a component of a cultigen can be accepted as a cultivar if it is recognisable and has stable characters. Therefore, all cultivars are cultigens.
Cultivars are distinct from plant varieties, which are a taxonomic level below subspecies, and there are differences in the rules for the creation and use of plant variety and cultivar names. The naming of cultivars has become complicated in recent years by the use of plant statutory patents and the recognition of plant breeders' rights.
[More to come ...]
