Improved varieties refer to varieties with high yield, good quality, timely product supply and high economic value produced by adopting excellent cultivation techniques in suitable areas and farming conditions.
Developing agricultural production and improving agricultural production level are basically achieved through two closely related ways:
1. Improve the genetic characteristics of plants, and select new varieties that meet the requirements of agricultural technology progress and have stronger adaptability-breeding.
2. Improve cultivation techniques and conditions, and give full play to the genetic potential of variety cultivation.
Section 1 Evolution and Genetic Improvement of Plants
Evolutionary process means that all kinds of plants in nature, including varieties used for cultivation, are evolved from relatively primitive plants and are in the process of continuous evolution and development.
Darwinists believe that the evolution of all living things, including wild plants and crops, depends on three basic factors: variation, heredity and selection; Variation and inheritance are the internal causes and foundations of evolution, and selection determines the development direction of evolution; Natural evolution is the evolution of natural variation and natural selection.
Artificial evolution means that horticultural plants and other crops cultivated now are all formed by artificial domestication, cultivation and selection from the original wild type.
Plant breeding is actually the artificial evolution of crops, making proper use of natural evolution.
Modern Darwinism holds that population is the basic unit of evolution; Species are isolated populations; Mutation and gene recombination produced by hybridization are the basic raw materials of evolution; The basis of selection lies in differential reproduction, which causes the change of gene frequency in the intermediate population; Isolation promotes the formation of new types. The basic elements of evolution are mutation, gene recombination, separation and selection.
Genetic improvement refers to crop variety improvement.
Section 2 The concept of crop varieties and the function of improved varieties
Cultivated variety (variety. ) is a cultivated plant group that has been cultivated and created by human beings, and its economic characters and agricultural biological characteristics meet the requirements of production and consumption. Under certain cultivation conditions, it can be distinguished from other taxa according to the specificity of morphology, cytology and chemistry, and its main characters are similar among individuals, and its important characteristics can be maintained through appropriate reproduction (sexual or asexual).
Variety is not a taxon of botany.
Characteristics of crop varieties:
1. specificity means that as a variety, there is at least one identifiable marker trait that is obviously different from other varieties.
A strain refers to a population whose individual traits are different from the original variety, but whose other forms are basically the same as the original variety.
2. Consistency refers to the adoption of a breeding method suitable for this variety, except for foreseeable variation, and its related characteristics after breeding.
Consistent with characteristics or characteristics. Individuals in the same variety should be relatively consistent in plant type, growth habit, phenology and main economic characters of products.
Predictable variation refers to the variation of some characters or characteristics due to the influence of external environmental factors, such as plant height and growth period.
3. Stability means that the related traits or characteristics of the variety remain relatively unchanged after repeated reproduction or at the end of a specific reproduction cycle.
4. Regionality means that the biological characteristics of varieties adapt to the ecological environment and agricultural technical requirements of a certain area.
5. Timeliness means that the yield, quality and adaptability of this variety meet the needs of production and consumption in a certain period of time.
The role of improved varieties:
1. Increase the output per unit area
2. Improve product quality
3. Improve insect resistance and reduce pesticide pollution.
4. Enhance adaptability and stress resistance, and save energy consumption in protected production.
5. Extend the supply and use cycle of products.
6. Conducive to the reform of farming system and the development of mechanization, adapt to intensive management and save labor.
Section 3 Plant Breeding and Plant Breeding Science Plant breeding is a science that studies the principles and methods of cultivating and propagating excellent plant varieties.
History of plant breeding: