Producer: Popular Science China
Producer: Bi Kun (Chinese Agricultural Society "Knowledge is Power" micro-platform)
Producer: Computer Network Information Center, Chinese Academy of Sciences
Recently, major news websites have rushed to report that the salt-tolerant rice planted by Yuan Longping's "seawater rice" team and the Jiangsu Provincial Agricultural Technology Extension Station has been tested in the Lingken District of Rudong Li Tea in Jiangsu Province, and the average yield of "Super Excellent Qian" salt-tolerant rice has reached 802.9 kg, which experts said has set a new record for high yield of rice in saline-alkali land. Because of its miraculous characteristics of salinity tolerance, seawater rice has attracted much attention from all walks of life.
So what is seawater rice? How was seawater rice discovered?
<h1 class = "pgc-h-arrow-right" > seawater rice: the vanguard warrior of desert-turned-oasis</h1>
Seawater rice, a figurative term for saline-tolerant rice, is named for its ability to grow in saline land where "seawater passes" such as seaside mudflats. Just by the name, one might think that seawater rice is rice grown in the sea, but in fact, seawater rice is just not afraid of short-term soaking in seawater.
In general, ordinary rice seeds cannot germinate in brine with salinity of more than 0.3%, and plants cannot absorb water and will die due to dehydration. Seawater rice is just the opposite, and can germinate normally in brine at concentrations of 0.9%-1.2%. At high tide, rice seedlings are submerged by seawater for three or four hours, and seawater rice grows faster after low tide.
△ Heavily saline land with seawater rice
Image source: Xinhua News Agency reporter Gao Han
Originally a saline land and desert with no grass, seawater rice may become the vanguard warrior who turns the desert into a green mountain. Why?
As we all know, the traits of organisms are mainly determined by genes. According to whole genome sequencing and comparative transcriptome analysis, through the comparison with the genome sequences of 3000 rice varieties in 89 countries, it was found that seawater rice is a relatively old subspecies of indica rice, with 64869 unique variants and a large number of salt-inducing genes. This unique gene can help seawater rice thrive in a saline environment.
It has been observed that the root system of seawater rice is particularly developed, and the root depth can reach 30-40 cm. The plant is much taller than ordinary rice, and the length of the rice panicle after maturity can reach 23 cm. With these special physiological structures, seawater rice is not only resistant to salinity and alkali, but also has excellent characteristics such as waterlogging resistance, disease and pest resistance, and lodging resistance. Therefore, in the process of growth, it does not need to apply fertilizers, pesticides, the rice produced, although carmine, is a real green food.
△ Seawater rice
Image source: The Paper's reporter Zheng Chaoyuan
The rice of seawater rice has mango spines and protects the fruit, which is a clear characteristic of wild rice. Seawater rice, on the other hand, began with the accidental discovery of a wild rice plant.
how was <h1 class="pgc-h-arrow-right" > seawater rice discovered? </h1>
According to the data, the international began to study the cultivation of salt-tolerant rice varieties, and it goes back to 90 years ago, when Sri Lanka discovered a strong salt-tolerant local variety Pokkali. From 1944 to 1945, India developed a hybrid breeding program for salt-tolerant rice, promoting the salt-tolerant rice varieties Kala Rata l-24 and Bhura Rata 4-10, bangladeshi bred salt-tolerant rice varieties BRI, BR 203-26-2, Sail, etc. Since 1970, the International Rice Research Institute (IRRI) has identified 10 salt-tolerant varieties from 9,000 rice varieties and families, including materials such as Pokkali, Getu and Nona Bokra, providing technical reserves for the breeding of rice salinity-tolerant varieties, and proposing rice salt tolerance identification standards and methods in 1979. In addition, Pakistan, Japan, the United States, the United Kingdom, Australia and other countries have also carried out research on the salt tolerance of rice.
China started late in the research of salt-tolerant rice, starting from the "National Rice-Wheat Salinity Resistance Cooperation Conference" held in 1981, and the identification of salinity tolerance of rice seed resources was taken as a national scientific research project during the "Seventh Five-Year Plan" period, and national collaboration was carried out.
In recent years, the seawater rice storm that has blown in the media originated from Chen Risheng in Zhanjiang, Guangzhou. In 1986, when Professor Luo Wenlie, who graduated from the forestry and fruit major, conducted a census of beach mangrove resources in Hutoupo, Suixi County, Zhanjiang, he accidentally found a wild rice in the reed field and carefully removed 522 seeds of the wild seawater rice, thus opening a life path intertwined with seawater rice.
△ Chen Risheng in the seawater rice test field
Image source: China News Network
Chen Risheng learned rice breeding from scratch, and due to the long experimental cycle, it took 5 years to finally select and finalize a new strain named "Haidao 86". Since 1992, Chen Risheng has continuously cultivated and promoted sea rice 86 to saline-alkali ground trials throughout the country, gradually expanding the scope to 3,000 mu, and the yield per mu has increased from 50 kg to 150 kg. In 2014, after the on-site inspection of rice experts organized by the Ministry of Agriculture, Haidao 86 was unanimously recognized as a specific rice germplasm resource with high scientific research and utilization value. Chen Risheng has been working silently for nearly 30 years, and finally the world knows it.
Academician Yuan Longping, the "father of hybrid rice", wrote to Wan Gang, then minister of science and technology, after inspecting seawater rice, saying that seawater rice has extremely high scientific research and utilization value, no less than male sterile wild rice. He integrated all aspects of resources and led the establishment of the Qingdao Seawater Rice Research and Development Center, which promoted saline-tolerant rice to different ecological regions such as Golmud City in Qinghai Province and the Tropical Desert Region of Dubai at high altitudes, and combined with rice hybridization technology, increased the yield of seawater rice per mu to 600 kg.
<h1 class="pgc-h-arrow-right" > the value and future of seawater rice</h1>
Seawater rice can use traditional unusable land such as saline-alkali land to ensure food security to a certain extent, and can effectively cope with the severe challenges facing food security. According to the Food and Agriculture Organization of the United Nations, 820 million people still suffer from hunger worldwide, while 950 million hectares of saline land are underutilized. It is estimated that 200 million mu of saline-alkali land in China has the potential to grow rice, and if 250 kg of seawater rice is planted, it can increase the yield of grain by 50 million tons and feed about 200 million more people.
△ The staff harvests seawater rice
Image source: Surging News reporter Liu Ji
Experiments in many places have shown that by planting seawater rice for 3-5 consecutive years, saline-alkali land can be transformed into land that can be cultivated by common crops. In some places, through the cultivation of seawater rice, the small environment of the saline-alkali land area has been changed, and even birds such as egrets have been attracted to inhabit, and biodiversity has been restored to a certain extent.
At present, although the genome sequencing has filled the gap in the molecular research of seawater rice and laid a molecular foundation for the cultivation of new varieties of salt tolerance, what is the specific salt tolerance mechanism has yet to be analyzed by scientists on the genes of seawater rice. With the improvement of salt tolerance, the still controversial problem of dilution irrigation of seawater should be resolved to some extent.
Resources:
1、https://xueqiu.com/5124430882/160943911?page=1
2. Dragon Fly. Differences in rice fertilization in different regions[J]. Planting and Breeding, 2011, 000(021):9.
3、http://news.gdzjdaily.com.cn/zjxw/content/2017-08/25/content_2239099.shtml
4、https://www.sohu.com/a/195717100_260616
5、http://www.chinanews.com/gn/2018/01-03/8414831.shtml
6、http://www.xinhuanet.com/2018-07/20/c_1123151882.htm