A Summary of Methods for Purity Identification of Crop Seeds
Wang Congyan Hu Ying Guo Erhui Tian Chaoyang Li Xiaohui
(College of Life Sciences, Henan Agricultural University, Henan Academy of Agricultural Sciences)
High-yield, high-quality, and disease-resistant varieties are the preconditions for increasing farmers' income from agricultural production. However, the quality of seed quality is the key to the full play of the characteristics of varieties, and seed purity is an important indicator of seed quality. The term "genetic purity of seed" refers to the percentage of seeds (or spikes per plant) of the species in the test sample to the total number of samples tested. Whether the seeds, seeds, or genus of a batch of seeds are the same as those on the label and whether they are genuine or not are called the "genuineness of seed". At present, China's relevant laws and regulations regarding the control of seed quality are still not perfect, and the seed quality detection technology is still not perfect. Therefore, the occurrence of counterfeiting and sale of counterfeit goods has occurred from time to time, which has greatly damaged the interests of the country and farmers and has become a potential obstacle to promotion of improved varieties and increased crop yields. To solve this problem, in addition to the need to improve relevant laws and regulations, it is necessary to establish a simple and fast, accurate and economical method for the detection of seed purity.
With the rapid development of biochemical analysis and molecular techniques, the identification of crop varieties and the method of seed purity testing have been identified from the observation of appearance morphology, and they have been developed to the physiological and biochemical levels and the identification of DNA molecules. At present, the crop seed purity identification technology can be roughly divided into four categories: first, morphological observation and identification technology, second, physical chemical identification technology, third, protein electrophoresis identification technology, and fourth, identification of DNA molecular markers.
1 Morphological Observation and Identification Technology
1.1 Identification of seed morphology
Differences between varieties are sometimes reflected in the differences in the appearance of seeds. Seed morphological characteristics are one of the most stable and reliable traits in the life history of plants, and they are an important basis for identifying varieties. For watermelon seeds, they can be distinguished according to the characteristics of seed size, shape (aspect ratio), plumpness, and color luster. This method is simple, fast, convenient, and intuitive. At present, it is widely used in production. However, as far as seeds are concerned, the morphological characteristics that can really be used for species identification are limited, and the seed morphology is more susceptible to external environmental conditions such as climate, water and fertilizers during seed maturation, which will make use of the differences in seed morphology. The identification of seed purity poses further difficulties. When there are many varieties and the differences in morphology between varieties are small, it is difficult to distinguish them. Therefore, the accuracy is relatively low.
1.2 seedling morphology identification
The seedling morphology identification method, also called the field planting identification method, is a traditional, reliable and accurate method of purity identification. Seedling morphological identification is the determination of seedlings and plants in which the seeds are planted under a consistent controlled environment, based on the morphological characteristics and biological characteristics of the seedlings or plants during the reproductive period. The best time of identification is the obvious period of typical traits of crops, and the best time of different crop identification is different. The seedling morphology identification method has significantly expanded the use of the seed morphology method and the rapid method because there are many more traits that can be identified, and it is a commonly used method for indoor purity identification.
Identification of seedlings can be done in two ways: The first approach is to provide conditions for accelerated development of the plant, such as conditions that give the seedlings accelerated growth and development (such as higher temperatures and long days), or to reduce the seasonal requirements of the plant when the seedlings When the development stage is suitable for identification, the identification is carried out. When the seedlings reach a suitable development stage, the color of the coleoptile and mesocotyl of all or part of the seedlings is identified. Another way is to allow the plants to grow under certain stress conditions and identify the species based on the different responses of different species to stress. If the nutrient conditions are controlled, cultivar growth in the absence of nutrients, especially in the absence of phosphorus, will accelerate the development of the purple or red pigments of the seedling hypocotyl system, or expose the seedlings and plants to growth under insecticide conditions. Insecticide damage response and record the extent of insecticide change in growth.
The seedling morphology identification method is mainly based on the morphological characteristics, heterosis, adverse physiology, resistance level, or character markers of a certain period of growth. In the life history of plants, genes are expressed sequentially, controlled at a specific stage by specific genes, and thus exhibit traits at specific stages, such as cotyledon shape, leaf color, leaf margin color, budding sheath color, seedling phase, Root development, true leaf birth time and so on. Different cultivars can be distinguished by these traits.The seedling morphology identification method is carried out under specific conditions, which is a simple equipment, easy to operate, low cost, short identification cycle, the impact of the human factors of the appraisers is small, more objective, the result is relatively accurate, is a reliable indoor inspection method, Widely used in production. However, this method also has its limitations: Firstly, it requires a long period of time and labor, and is subject to seasonal restrictions. It is difficult to determine the purity of the seed produced in the current year, which causes difficulty in ranking and invoking seed acquisition; secondly, the impact on environmental conditions The resulting mutation is more difficult to discriminate from the genetic variation of the breed; at the same time, the identification results are also influenced by the technical level and the identification experience of the appraiser; in addition, the two genetically similar seed combinations can be used in individual differences. On the difference, but it is difficult to distinguish them within the group; finally the method can be used to identify relatively few traits, so the seedling morphology identification method can only be used for the identification of significant differences between varieties. Therefore, the seedling morphology identification method has been limited in actual production.
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