Heterosis is a common phenomenon in biology, and using heterosis to improve crop yield and quality is one of the main achievements of modern agricultural science.
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Ethnicity
Yuan Longping1971February was transferred to Hunan Academy of Agricultural Sciences to specialize in hybrid rice research. In order to strengthen and coordinate the scientific research of hybrid rice, Hunan Hybrid Rice Research Center, a national specialized research institution of hybrid rice, was established in June, 1984, and then the National Hybrid Rice Engineering and Technology Research Center was established, with Yuan Longping as its director. 1995 was elected as an academician of China Academy of Engineering. Known as the father of hybrid rice.
From 65438 to 0960, Yuan Longping learned from some periodicals that hybrid sorghum, hybrid corn and seedless watermelon have been widely used in domestic and international production. This made Yuan Longping realize that the laws of gene separation, free combination and chain exchange put forward by geneticists Mendel, Morgan and their followers are of great significance to crop breeding. Therefore, Yuan Longping jumped out of the circle of asexual hybridization theory and started the experiment of sexual hybridization of rice.
1in July, 960, he found a unique rice plant in the experimental field of early rice conventional varieties. The next spring, he sowed the seeds of this mutant into the experimental field, and the results proved that this rice that stood out last year was an out-and-out "natural hybrid rice". He believes that since "natural hybrid rice" exists objectively in nature, as long as we can explore its laws and mysteries, we will certainly cultivate artificial hybrid rice according to our requirements, so as to make use of its hybrid advantages and increase rice yield. In this way, Yuan Longping broke through the traditional idea that rice is a self-pollinating plant without heterosis in practice and reasoning. Therefore, Yuan Longping immediately turned his energy to the new subject of cultivating artificial hybrid rice.
During the rice flowering period from 1964 to 1965, he and his assistants stood in the scorching sun every day, stepped on the soil and bowed their heads, and finally found six natural male sterile plants in the rice field. After two years of observation and experiment, he has a rich understanding of rice male sterile materials. Based on the accumulated scientific data, he wrote a paper, Rice Male Sterility, which was published in Science Bulletin. This is the first time to discuss rice man in China.
The paper on sterility not only describes the characteristics of rice male sterile plants in detail, but also divides the materials found at that time into three types: no pollen, pollen abortion and partial male sterility. Since 1964 discovered "natural male sterile plants", Yuan Longping and his assistants spent six years crossing more than 3,000 varieties with 1000, but still failed to cultivate sterile lines with sterile plant rate and sterility degree reaching 100%. Yuan Longping summed up the experience and lessons in the past six years, and according to the infertility observed by himself, he realized that it was necessary to jump out of the small circle of cultivated rice and re-select parent materials, and put forward a new idea of "crossing distant wild rice with cultivated rice". Under the guidance of this idea, Yuan Longping led his assistant Li Bihu to find the male sterile plant 1970+065438+ in the common wild rice community in Hainan Island on June 23rd, and tested it with Fangao and Jingan 66, and found that it has the ability to maintain the wild sterile plant, which opened a breakthrough for cultivating the rice sterile line and the subsequent "three lines".
Should we seal up the precious data of "wild defeat" and study it behind closed doors, or mobilize more scientific and technological personnel to tackle the problem together? On this important issue of principle, Yuan Longping unequivocally and unreservedly informed the national breeding experts and technicians of his latest discovery in time, and generously distributed the "wild failure" discovered after going through hardships to the relevant units for research, and cooperated with the "third-line" support.
From 65438 to 0972, the Ministry of Agriculture listed hybrid rice as a national key scientific research project, forming a national collaborative research network. 1973 on the basis of breaking through the "sterile line" and "maintainer line", the majority of scientific and technical personnel selected more than 1000 varieties for cross test screening, and found more than 1000 varieties with restoring ability. Zhang Xiancheng, Yuan Longping and others took the lead in discovering a number of restorer lines represented by IR24, which have strong advantages and large amount of pollen, and the restoration degree is over 90%.
1973 10 Yuan Longping published a paper entitled "Progress in Breeding Three Lines by Wild Abortion", which officially declared the success of "Three Lines" matching of indica hybrid rice in China. This is a major breakthrough in rice breeding in China. Then, he and his colleagues overcame the "heterosis obstacle" and "seed production obstacle" successively, paving the way for the utilization of rice heterosis.
In fact, Yuan Longping has this concern. As early as 1986, in his paper "Breeding Strategy of Hybrid Rice", he put forward that the breeding method of hybrid rice can be divided into three stages: three-line method, two-line method and one-line method, that is, the breeding procedure develops from complex to simple, and the efficiency is getting higher and higher; From the level of heterosis utilization, it can be divided into three stages: interspecific heterosis utilization, interspecific heterosis utilization and distant heterosis utilization, that is, heterosis utilization is developing in a stronger and stronger direction. According to this idea, every time hybrid rice enters a new stage, it is a new breakthrough, which will promote rice production in by going up one flight of stairs. 1In August, 1995, Yuan Longping solemnly announced that after nine years, the research of two-line hybrid rice in China had made a breakthrough, which could be widely popularized in production. As envisaged in Yuan Longping's breeding strategy, the two-line hybrid rice has indeed shown a better yield-increasing effect, generally increasing the yield by 750- 1500 kg per hectare compared with the three-line hybrid rice in the same period, and the rice quality has been greatly improved. Up to now, in the production demonstration, more than 80,000 mu of two-line hybrid rice/kloc-0 has been planted nationwide. At present, the national "863" plan has taken Pei 'ai series combination as the pioneer combination of two-line hybrid rice, and has increased its promotion throughout the country.
1In August 1998, Yuan Longping launched an attack on a new commanding height. He put forward the research topic of cultivating super hybrid rice to Premier Zhu. Premier Zhu was very happy after hearing the news and immediately allocated100000 yuan to support it. Yuan Longping was greatly encouraged. At Sanya Farm Base in Hainan, Yuan Longping led a team of cooperative scientific research units from more than ten provinces and regions across the country to fight day and night to overcome the difficulties of two-line hybrid rice. After nearly a year's efforts, super hybrid rice was successfully planted in a small area, with a yield of 800 kilograms per mu, and was successfully introduced in Southwest Agricultural University and other places. At present, super hybrid rice is heading for large-scale trial planting and popularization.
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Related terms
Male sterile line: It is a kind of female rice with male degeneration (mainly pollen degeneration) but normal pistil. Because pollen can't live, it can't pollinate and bear fruit by itself, and it can only be fertilized and borne by exotic pollen. Therefore, with this mother rice as a genetic tool, a large number of hybrid seeds can be produced by artificial pollination.
Maintainer: It is a normal rice variety, and its special function is that after its pollen is given to the sterile line, the offspring produced are still male sterile. Therefore, with the help of maintainer lines, sterile lines can be propagated from generation to generation.
Restorer line: It is a normal rice variety. Its special function is that the hybrid male produced by its pollen returns to normal and can be self-bred. If hybrids have advantages, they can be used for production.
Three-line hybrid rice: refers to three-line breeding of male sterile line, maintainer line and restorer line. Sterile lines provide the possibility for mass production of hybrid seeds. Breeding sterile lines with maintainer lines and pollinating sterile lines with restorer lines to produce hybrid rice with male restorer advantages.
Two-line hybrid rice: a kind of rice named photo-thermo-sensitive sterile line, whose fertility transformation is closely related to the length of sunshine and temperature, and it shows male sterility under long-term high temperature conditions; Under the condition of short-day average temperature, male fertility recovered. Hybrid rice bred by photo-thermo-sensitive male sterile line can be used with restorer line for seed production in long sunshine in summer, and can reproduce itself in autumn or spring in Hainan, so it is no longer necessary to use maintainer line to propagate male sterile line, so the hybrid rice prepared by photo-thermo-sensitive male sterile line is called two-line hybrid rice.
Super hybrid rice: Super high-yield rice breeding is a key project of many countries and research institutions in recent 20 years. Japan took the lead in developing super-high-yield rice breeding in 198 1, and plans to increase rice yield by 50% in 15. 1989, the international rice research institute launched the "super rice" breeding plan, which required to cultivate super rice with a yield of 20%-25% higher than the highest variety at that time in 2000. But their plan has not been realized so far. The Ministry of Agriculture of China launched the China Super Rice Breeding Plan in 1996, in which the first-season yield of hybrid rice was 700 kg per mu in the first phase (1996-2000) and 800 kg per mu in the second phase (200 1-2005).
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Breeding technical route of super hybrid rice
(1) Two lines and three lines developed synchronously, and morphological improvement was combined with the utilization of heterosis among subspecies.
(2) For the middle and lower reaches of the Yangtze River, build an excellent plant-type hybrid rice combination with high canopy height, short panicle layer, low center of gravity, large and uniform sink and high lodging resistance; In view of the single-season rice area in southwest China, the intersubspecific heavy panicle hybrid rice combination was selected.
(3) Using indica-japonica heterosis to select parents, and using interspecific heterosis.
(4) Using distant beneficial genes with the help of biotechnology.
(5) According to the characteristics of super hybrid rice, the cultivation techniques of super high yield were established.
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Fertilization method for hybrid rice
According to the determination of basic application amount of organic fertilizer, 50%-60% of nitrogen and 70% of phosphorus and potassium in the total fertilizer requirement of hybrid rice come from soil. Insufficient fertilization will consume too much nutrients in the soil and reduce fertility. Increasing application of organic fertilizer is an important way to improve fertility. Therefore, in hybrid rice production, the application amount of organic fertilizer should account for 40% of the total fertilization amount.
Tillering fertilizer can be applied to early rice 5 days after transplanting and to late rice 3 days after transplanting. Tillering fertilizer should be applied in stages. For the first time, 6-7.5 kilograms of urea should be applied per mu, and every 7 days or so, according to the seedling situation, 4 kilograms of urea should be applied per mu to the fields with poor growth; 5-7.5 kilograms of potassium fertilizer should be applied to the land with little organic fertilizer and potassium deficiency per mu.
According to the different application time, ear fertilizer can be divided into flower-promoting fertilizer and flower-keeping fertilizer. Where fertilization is suitable in the early stage and the seedlings are in good condition, flowers are generally protected and grains are increased, only flower protection fertilizer is applied, and about 2.5 kilograms of urea is applied per mu. If there is insufficient fertilization in the early stage, the number of seedlings in the group is small and the individual growth is poor, it is necessary to apply both flower-promoting fertilizer and flower-protecting fertilizer, and apply 5 kg of urea per mu each time. Hybrid rice has a great demand for potassium fertilizer, so it should be combined with topdressing nitrogen fertilizer after the sun rehydrates, and topdressing potassium fertilizer is about 2.5 kg per mu.
Before heading with granular fertilizer, look at the fields with too light seedlings, and apply 22.5 kilograms of urea per mu; Apply 2.5-3 kg urea per mu to the land that falls yellow prematurely after full heading; For normal growing fields, 50 kg of water and 5-7.5 kg of urea should be sprayed per mu. Because of the great demand for phosphorus and potassium in the late growth stage of hybrid rice, it is necessary to use 150-200 grams of potassium dihydrogen phosphate per mu, and spray 50 kilograms of water 4-6 days before heading or 2-3 days after heading.
If you want to get seeds for production, you can't use the seeds left by hybrid offspring, especially rice. I can see that you have some knowledge of biology and genetics. You know, hybrids are the most advantageous combinations that breeders have finally selected after crossing with different parents for a long time. Usually, there are complementary effects between genes, such as crossing with parents with disease resistance but poor quality and parents with high quality but not disease resistance and low yield, which may produce hybrids with disease resistance, high yield and high quality. After self-crossing in hybridization, genes will be separated and recombined, so different genes may be combined together first, and diseases, low yield and inferior types may occur, which is definitely not what you want. Why can't rice especially use the offspring of hybrids as production seeds? At present, most rice hybrids use male sterile lines as female parents. Because of the interaction between nuclear genes and cytoplasmic genes, hybrids are fertile. However, sterile plants may be separated after selfing, and this part of rice plants can not bear fruit, so the yield will of course be affected. This is certainly not what you need.
Of course, if you want to cultivate your own varieties, you can separate excellent materials from hybrids. In fact, many breeders have selected the materials they need from the offspring of excellent hybrids. As you said, you can not only separate its parents, but also get excellent materials beyond its parents. But it takes time, patience, experience and a little luck.
You said it was better than Yuan Longping looking around in the fields, which is wrong. Yuan is not looking around, but looking for the natural variation he needs (usually the frequency of variation is only one in hundreds of thousands). This variation may be an unprecedented new type, which can bring revolutionary changes, rather than being separated from ordinary materials. As a matter of fact, he was lucky enough to find it and make full use of it, thus enabling China's hybrid rice research to be in the leading position in the world.
You said: "It is very difficult to study the secret of hybrid rice from the seeds you bought, but there are still some information." That's right. Theoretically, the secret of hybridization can be solved from the seeds bought. But it will take a long time, because it will take five generations to get stable homozygotes. Whether this homozygote can be used as a parent material still needs the experience and vision of the breeder. So from this perspective, breeding is not only a technology, but also an art.
Let's just say that the rice grown from hybrid seeds is not easy to produce, because the characters are unstable. At first, the traits of parents may meet the planting requirements, but after the morphological separation of offspring, inferior seeds will be produced, because the traits are determined by genotype and performance. Through hybridization, we gather pure and optimal traits together, but if we want to use them in agricultural production, we have to go through many generations of self-screening, take out heterozygotes and keep the traits stable.
Ps: (Yuan Longping looked around in the field at that time), this is the sorrow of scientific rigor!
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Super-high yield plant type model of rice
Plant height: 100 cm
Stem height: 75 cm
Tillering ability: medium.
Plant type: moderately compact
The upper three leaves: long, straight, narrow, concave and thick.
Spike type: drooping
Ear number: 2.7 million/ha
Single ear weight: about 5 grams
Harvest index: 0.55
Daily output: 100 kg/ha
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Utilization of heterosis among subspecies
There are two subspecies of rice: indica rice and japonica rice. Theoretically, the yield of intersubspecific hybrid rice can be increased by more than 30%.
At present, the main problems in the utilization of heterosis among subspecies have been basically solved. The newly bred super hybrid rice between subspecies has large panicles and many grains, and good quality, which has increased the yield by more than 20% compared with the existing hybrid rice in production test and demonstration.
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Yuan Longping-the Father of Hybrid Rice in the World
Farmers in China said that eating depends on "two levels", Deng Xiaoping (responsibility system) and Yuan Longping (hybrid rice). According to the western world, hybrid rice is "Oriental magic rice", and its other name is "China magic rice". His achievements not only solved the problem of eating in China to a great extent, but also were regarded as the magic weapon to solve the world hunger problem in the next century. Internationally, hybrid rice is even regarded as the fifth great invention of China after the four great inventions, which is called the "second green revolution".
Yuan Longping,/kloc-0, born on September 7th, 930, is an academician of China Academy of Engineering. He is currently the director of the National Hybrid Rice Work Technology Center, the Hunan Hybrid Rice Research Center and the vice chairman of the Hunan Provincial Political Consultative Conference. China, the founder of hybrid rice research, was the first person in the world to successfully utilize the heterosis of rice. Yuan Longping has been engaged in the theoretical research of hybrid rice breeding and the practice of seed production technology for a long time. 1964 first put forward the idea of cultivating "sterile line, maintainer line and restorer line" to make use of rice heterosis, and carried out scientific experiments. 1970, he and his assistants Li Bihu and Feng Keshan discovered a male sterile wild rice in Hainan, which became the key to break through the "three lines" matching. 1972 bred the first rice male sterile line "Erjiunan 1 A" and the corresponding maintainer line "Erjiunan 1 B" in China, and bred the first strong combination "Nanyou No.2" in the following year, and studied a set of seed production techniques. 1986 puts forward the strategic assumption that hybrid rice breeding is divided into "three-line method using interspecific heterosis, two-line method using interspecific heterosis and one-line method using distant heterosis". Known as "the father of hybrid rice" by peers.
He has successively won the Gold Award for Outstanding Inventor of the United Nations Intellectual Property Organization, the UNESCO Science Award, the Jean-Claude Award of the Jean-Claude Foundation of the United Kingdom, the World Hunger Saving Award of the Fanster Foundation of the United States, the Food safety award of the United Nations Food and Agriculture Organization, the Nikkei Asia Award of Japan, the Pioneer Scientist Award for Utilization of Crop Heterosis, and the Yue Guang International Rice Award of Japan.
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Enlightenment of hunger
From 65438 to 0960, there was a nationwide famine in China, and Yuan Longping and his students were also threatened by hunger.
On one occasion, he took more than 40 agricultural school students to build a brigade in Xizhou Commune, Qianyang County to participate in productive labor. One day, the landlord always came back with a load of rice in the rain. He told Yuan Longping that this is the rice he bought from another village.
"Why do you want to change rice seeds?" Yuan Longping asked.
"There is a high slope open space, full of food and high yield. Fertilization is not as good as diligent planting. " Lao Xiang said, "Last year we used the rice seeds we bought there, and the yield in the field increased. We didn't eat the grain that the country sold back this year. "
In the face of famine, villagers did not wait for state relief, but took the initiative to find ways to increase production. Yuan Longping was very moved.
This incident inspired him greatly: improving varieties and increasing production is of great significance to overcoming hunger. He thought that in addition to teaching good classes, he should also make some achievements in agricultural scientific research and cultivate good seeds with high yield for fellow villagers.
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Principle of increasing yield of hybrid rice in Yuan Longping
Hybrid rice is produced by crossing different rice seeds with each other. Rice is a self-pollinated crop, which is not conducive to the preparation of hybrid seeds. In order to cross two different rice varieties, the stamens of one variety should be emasculated or killed artificially, and then the stamen pollen of the other variety should be given to the emasculated variety, so that there will be no false hybrid rice which is self-pollinated by the emasculated variety. However, if tens of thousands of rice flowers are emasculated and pollinated manually, the workload is huge, and it is actually impossible to solve a large number of seeds used in production. So a kind of rice was bred as the female parent, which has a special personality, with thin stamens and withered anthers. You can't fertilize and sow with your own pollen.
In order not to cut off the offspring of the mother, we should find two objects for it. The characteristics of these two objects are different: the first object looks very much like the female parent, but has sound pollen and developed stigma. When its pollen was given to its female parents, it gave birth to a daughter. She looks exactly like her mother, and she is also a female parent. The stamens are thin and degenerate, the anthers are withered and deformed, and there is no fertility. The other object is completely different from the female parent in appearance, generally taller than the female parent, and also has sound pollen and developed stigma. After its pollen was given to the female parent, it gave birth to a son, stronger than both parents. This is the hybrid rice we need, a female parent and its two objects. According to their different characteristics, people have given three names respectively: the female parent is called sterile line, and two objects, one is called maintainer line and the other is called restorer line, which is called "three lines" for short. With the "three-line" system, we know the preparation of hybrid rice in production: a breeding field and a seed-making field should be planted in production, and a sterile line and a maintainer line should be planted in the breeding field. When both flowers bloom, the pollen of the maintainer line will be transferred to the sterile line by the wind, and the sterile line will get normal pollen results, and the offspring will still be sterile, thus achieving the purpose of breeding the sterile line. We can keep a part of the propagated sterile line seeds for further propagation in the next year, and the other part can be used for seed production together with the restorer line. When both the sterile line and the restorer line in the seed-making field bloom, the pollen of the restorer line will be transferred to the sterile line, and the offspring produced by the sterile line will be the hybrid rice seeds planted in the field. Because the male and female stamens of the maintainer and restorer lines are normal and self-pollinated, the seeds they produce are still the descendants of the maintainer and restorer lines.
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Magazine of the same name
Hybrid Rice is the only professional technical publication in hybrid rice field at home and abroad so far. With the aim of "promoting the pioneering research and development of hybrid rice, transforming the research results into productive forces as soon as possible, promoting the continuous development of hybrid rice research and production, and better serving China's socialist modernization", we adhere to the publishing policy of "combining popularization with improvement, focusing on improvement". The publication covers all aspects of research, development and application of hybrid rice, integrating academics, technology, popularization and information. It has successively set up special topics and reviews, breeding and breeding, breeding and seed production, cultivation techniques, basic theories, new combinations, translation, briefings, newsletters, foreign trends, rice quality, academic contention and special reports. It has been distributed to all provinces (cities, districts) with rice cultivation in China, and has been distributed to the United States, India, Vietnam and other countries and regions 10. Readers are agricultural scientists and technicians, teachers and students in agricultural colleges, agricultural production and management personnel and knowledge farmers.