The principle of hybrid rice is to produce it through the crossbreeding of different rice species, and rice is a self-pollinating crop. Yuan Longping used hybrid rice to greatly increase the yield and greatly increase the grain output. To cross two different rice species, the stamens of one variety must first be artificially emasculated or killed, and then the stamen pollen of the other variety should be given to the emasculated variety, so that self-pollination of the emasculated variety will not occur. of false hybrid rice. With the application and promotion of hybrid rice, the yield per unit area has been increased and the amount of seeds used has been reduced; the hybrid rice direct seeding cultivation technology saves the traditional rice seedling cultivation process and directly sows the soaked and germinated rice seeds into the field. It is a simplified cultivation method that allows it to grow into seedlings and tillers until maturity.

In the 19th century, the Austrian scientist Mendel discovered the laws of inheritance, the separation of genetic factors, and the free combination of genetic factors through the famous "pea hybrid experiment." Hybridization refers to the method of recombining the genes of the parents and complementing their excellent traits through two genetically different varieties. Hybridization is a ubiquitous phenomenon in nature and is called "hybrid vigor." Rice flowers have male and female flowers wrapped in green husks. Normally, they grow together. When flowering and bearing fruit, the female flower can only accept pollination from its own male flower. If it is to be hybridized with other varieties, the male flower must be removed before it reaches sexual maturity to prevent self-fertilization. At this time, the remaining female flowers can be used as female parents and crossed with other male parents to produce hybrids. However, the efficiency of artificial castration cannot meet the needs of large-scale production applications. It was Academician Yuan Longping who published an important article "Male Sterility of Rice" in the "Science Bulletin" magazine sponsored by the Chinese Academy of Sciences. At that time, he proposed In order to use male sterile materials to complete hybrid seed production, the process of artificial emasculation can be eliminated. With this idea in mind, Yuan Longping and his team conducted long-term exploration and found a male-sterile wild rice in Hainan in 1970. Using this wild rice as the basic material, they successfully developed hybrid rice. technology. There is also a problem faced in this process, that is, if you want to take advantage of "hybrid vigor", hybrids must be cross-produced every year, but this male sterile line has no reproductive ability, so the sterile line must reproduce offspring. You need to use other materials. Therefore, scientists have to match it with a "cousin" and use the pollen of the "cousin" to complete the pollination process, so as to ensure that the male sterile line has offspring, which is the "three-line hybrid rice" technology. It is this method that has led to a qualitative leap in grain yield per mu.