Scientific name: rice; English name: rice
Gramineae belongs to fibrous root system, with developed adventitious roots and panicles, and is self-pollinated. Annual cultivated grain. The culm is erect and 30 ~ 100 cm high. Leaves alternate two rows, linear-lanceolate, ligule membranous, 2-lobed. Panicle is loose; Spikelet oblong, squashed on both sides, containing 3 florets, glume degenerated, leaving only traces, top floret bisexual, lemma boat-shaped, awned; Stamens 6; Degenerate 2 flowers leave only the lemma under bisexual flowers, which is often mistaken for glume. Dianthus native to tropical Asia. It is one of the main food crops in the world. China's rice planting area accounts for 1/4 of the national grain crops, but the output accounts for more than half. The cultivation history has been 6000 ~ 7000 years. As an important food crop; In addition to eating caryopsis, it can also be used to make starch, wine and vinegar. Rice bran can be used to make sugar, extract oil and extract furfural, and is used in industry and medicine. Rice straw is a good feed, paper-making raw material and textile material, and rice buds and roots can be used as medicine.
Rice is an annual gramineous plant, with a plant height of about 1.2m, long and flat leaves, and an ear composed of many spikelets. The fruit is rice, which is called rice or rice after hulling. Nearly half of the world's population, including almost the whole population of East Asia and Southeast Asia, feeds on rice. The history of rice cultivation can be traced back to India around 3000 BC, and then gradually spread to the west and southern Europe in the Middle Ages. In addition to the ecotype called upland rice, rice is planted in coastal plains, tidal deltas and flood-stricken areas in tropical, subtropical and temperate regions. Sow the seeds on the prepared paddy field, transplant them to the paddy field with a water depth of 5- 10 cm around the dike at the seedling age of 20-25 days, and soak them in water all the time during the growing season. The harvested rice grains are called rice and have shells. When milling rice, the husk is often removed together with the rice bran layer, and sometimes a thin layer of glucose and talcum powder is added to make the rice grains shiny. Rice with only the husk removed during rice milling is called brown rice, which is rich in starch and contains about 8% protein and a small amount of fat, including thiamine, nicotinic acid, riboflavin, iron and calcium. Rice without husk and rice bran is called polished rice or white rice, and its nutritional value is greatly reduced. The way of eating rice is mostly cooking. In the East, the Middle East and many other regions, rice can be served with various soups, side dishes and main teas. By-products of rice milling include rice bran, ground rice bran powder and starch extracted from rice bran, all of which are used as feed. The oil obtained from rice bran processing can be used as food and industry. Broken rice is used to make wine, extract alcohol, and make starch and rice noodles. Rice husk can be used as fuel, filler and polishing agent, as well as fertilizer and furfural. Straw can be used as feed, bedding for livestock, roofing materials, packaging materials, mats, clothes and brooms. The main rice producers are China, Indian, Japanese, Bangladeshi, Indonesian, Thai and Myanmar. Other important producers are Vietnam, Brazil, South Korea, the Philippines and the United States. In the late last century, the average annual output of rice in the world was about 400 billion kilograms, and the planting area was about 65.438+0.45 billion hectares. 95% of the rice produced in the world is eaten by human beings.
Rice likes high temperature, high humidity and short sunshine, and has low requirements for soil, and paddy soil is the best. The lowest temperature of seedling germination is 10 ~ 12℃, and the optimum temperature is 28 ~ 32℃. The average daily temperature at tillering stage is above 20℃, and the optimum temperature for ear differentiation is around 30℃. Low temperature prolonged the differentiation of branches and glumes. The optimum heading temperature is 25 ~ 35℃. The optimum flowering temperature is about 30℃, lower than 20℃ or higher than 40℃, which seriously affects fertilization. The relative humidity is 50 ~ 90%. The key period of fruiting is from panicle differentiation to full filling stage; The population with balanced nutritional status and high photosynthetic efficiency is of great significance to improve seed setting rate and grain weight. A lot of water and mineral nutrients are needed at heading and fruiting stage; At the same time, it is necessary to enhance the root activity and prolong the functional period of stems and leaves. It takes about 500 ~ 800 kg of water to form 1 kg of rice.
Production covers all continents except Antarctica.
China is a country with the longest history of planting rice in the world. According to the research of Hemudu excavation in Yuyao, Zhejiang, rice was planted here as early as six or seven thousand years ago, more than one thousand years earlier than Thailand.
China's famous station rice is mainly produced in Tianjin. When Yuan Shikai was training in the station, he successfully planted it in the station area. Later, it was improved by Gaoli Zhuangzi, the landlord in the southern suburbs of Tianjin, and became today's post rice. After cooking, it tastes good, soft and delicious, and it has become one of the main foods in Tianjin. However, it was stopped for a long time as a four-old variety during the Cultural Revolution, and it was planted in a large area in the southern suburbs of Tianjin after the reform and opening up.
In recent years, the drought and lack of rain in a large area in northern China and the serious shortage of fresh water resources have once again hindered the cultivation of rice, and no rice has been planted for several years.
Transgenic rice goes from laboratory to field
According to Xinhua News Agency, the research on genetically modified rice, which has attracted worldwide attention, is moving from laboratory to field. The reporter recently learned from China Rice Research Institute that transgenic rice has entered the field release stage and is now applying for commercial production.
From 65438 to 0996, the research group headed by researcher Huang Danian of China Rice Research Institute developed herbicide-resistant transgenic hybrid rice for the first time in the world, which provided a new method to solve the purity problem of hybrid rice seed production. This achievement ranks first in the "1997 Top Ten Scientific and Technological Progress in China" selected by 500 academicians of Chinese Academy of Sciences. After that, the research group successfully prepared herbicide-resistant transgenic direct-seeded rice, which can save labor and time and eliminate weeds in rice fields.
In March last year, China Rice Research Institute and Zhejiang Qianjiang Biochemistry Co., Ltd. jointly established Zhejiang Jinsui Agricultural Genetic Engineering Co., Ltd., which officially kicked off the industrialization of genetically modified rice.
At present, Huang Danian and others have cultivated a number of excellent transgenic rice combinations and new lines. After laboratory research and intermediate tests in Fuyang, Lin 'an and Lishui, Zhejiang Province, these new varieties have been released and demonstrated in the field and are being applied to relevant departments for commercial production.
Breakthrough in Rice Gene Separation Technology in China
Scientists in China have successfully obtained nearly 2,000 rice cDNA fragments by using original gene isolation technology, and developed the first rice gene chip with unique functions in China.
This modular expression sequence tagging technology (M-EST) was first proposed by Professor Li Debao from Institute of Biotechnology of Zhejiang University, and recently obtained a patent in China National Intellectual Property Administration, China.
Thousands of densely arranged molecular microarrays integrated on the chip enable people to analyze a large number of biomolecules in a short time and obtain biological information in samples quickly and accurately, and the efficiency is hundreds of times that of traditional detection methods. It is praised by some scientists as another far-reaching scientific and technological revolution after large-scale integrated circuits.
The research team led by researcher Lin Hongxuan from Institute of Plant Physiology and Ecology, Shanghai Institute of Life Sciences, Chinese Academy of Sciences, and State Key Laboratory of Plant Molecular Genetics made a breakthrough in the research of rice yield-related functional genes, successfully cloned the quantitative trait gene GW2 for controlling rice grain weight, and elaborated the related biological functions and mechanisms, indicating that the gene has broad application prospects in high-yield molecular breeding. Related papers were published online in Nature Genetics, the top international journal of genetics, on April 8th.
Genetic improvement or genetic engineering is one of the effective means to increase crop yield. Searching for functional genes related to high yield has important theoretical significance and application value for high yield breeding of rice. Grain weight is one of the factors that determine rice yield. It is a complex quantitative trait controlled by multiple genes, and the genetic regulation mechanism of related molecules is still unclear.
Researcher Lin Hongxuan directed doctoral students Song Xianjun and Huang Wei to successfully clone the quantitative trait gene GW2 for controlling rice grain weight after years of painstaking research. A large number of detailed experimental results show that GW2, as a new E3 ubiquitin ligase, may participate in the degradation of protein, which promotes cell division, thus regulating the size of rice husk and controlling grain weight and yield. When the function of GW2 is lost or reduced, the ability of gene to degrade protein related to cell division will decrease, thus accelerating cell division and increasing the number of cells in rice husk, thus significantly increasing the width of rice grain, accelerating grain filling speed and increasing grain weight and yield.
Researchers introduced GW2 gene of large-grain varieties into small-grain varieties to cultivate new strains by molecular marker selection, and harvested 25 plants planted in the field respectively. Measure the yield of each plant. Compared with small grain varieties, although the number of grains per panicle of the new strain decreased, the yield per plant increased significantly due to the obvious increase of grain weight, which indicated that the gene was valuable in high-yield breeding. The effect of increasing production needs to be further investigated and verified by plot test. The research results provide new genes with independent intellectual property rights and important application prospects for crop high-yield breeding; A new viewpoint is put forward to clarify the molecular genetic regulation mechanism of crop yield and seed development.
Three reviewers of Nature Genetics unanimously spoke highly of this study: "We can now control the function of GW2 to obtain rice grains of appropriate size. At this point, I believe this is a work of great significance in the history of rice yield breeding. The experiments of gene location cloning, sequence analysis, transgenic phenotype identification and E3 ubiquitin ligase function are convincing. This is a masterpiece that will arouse great interest of geneticists. In this paper, a large number of in-depth experiments, including gene location cloning, gene structure analysis, function and phenotype identification, proved that the gene controlled rice grain size, and put forward valuable insights for the study of genetic regulation mechanism of crop seeds.
The panicle types of rice are as follows:
Heavy panicle type: the number of grains per panicle is about 200, and the middle panicle weighs about 5g.
Multi-spike type: less than 100 grains per spike.
Large spike type: per spike 120 grains.
Heavy panicle rice has large panicle and many grains, developed transportation organization and good grain enrichment, and the stem and sheath substances move quickly and much to the panicle in the later stage. While paying attention to field management in the early stage, we must strengthen fertilizer and water management in the later stage to prevent premature aging.
(1) Indica rice and japonica rice are two climatic ecotypes formed by long-term adaptation to different ecological conditions, especially temperature conditions, and there are obvious differences in morphological and physiological characteristics between them (Table 3- 1). Among the rice producing countries in the world, only China has both indica rice and japonica rice, with a large area and obvious geographical distribution. Indica rice is mainly concentrated in tropical South China and subtropical lowlands south of Huaihe River. The distribution range is narrower than japonica rice. Indica rice has the habit of heat resistance and strong light resistance. Its botanical characteristics are slender grain shape, poor rice viscosity, rough and hairy leaves, short capillary on the shell, easy to drop grains, similar to wild rice. Therefore, indica rice is a basic type of cultivated rice evolved from wild rice. Japonica rice is widely distributed, from the alpine mountain area in the south and the Yunnan-Guizhou Plateau to the vast areas north of Qinling Mountains and Huaihe River. The characteristics of poor light resistance, short and round grain shape, strong rice viscosity, little or no hair on leaves, long and dense glume and difficult to drop grains are quite different from those of wild rice. Therefore, it can be said that japonica rice is a variety that people gradually adapt to low temperature after introducing indica rice from south to north and from low to high.
(2) The fundamental difference among early rice, middle rice and late rice lies in their different responses to light. Early rice and middle rice are insensitive to light and can mature normally all year round. Late rice is sensitive to short sunshine, so it is strictly required to go through the photoperiod under short sunshine before heading and fruiting. Late rice is very similar to wild rice, which is a basic type directly evolved from wild rice. Mid-season rice is a variety of late rice differentiated under different temperature and light conditions. Rice in northern rice areas belongs to early rice or middle rice. (3) Rice and upland rice are planted in paddy field and upland rice is planted in dry land. The morphological difference between upland rice is small, but the physiological difference is big. Both upland rice and upland rice have aeration tissues, but upland rice seeds need less jiaozi, have strong water absorption and germinate quickly. Dry rice stems and leaves have developed protective tissues and strong heat resistance; Upland rice can be planted in dry land or in water, and some varieties can be cultivated as upland rice, but the yield of upland rice is generally low, upland rice is gradually replaced by rice, and only a small amount of upland rice is cultivated in northern rice areas.
(4) Non-glutinous rice and glutinous rice are the staple foods in China, and glutinous rice is used to make cakes or make wine. The main difference between them lies in the viscosity of rice grains, which is strong and weak. Viscosity is mainly determined by starch structure. The starch structure of glutinous rice is mainly amylopectin, while non-glutinous rice contains more amylose. Starch dissolved in iodine solution turns blue due to high iodine absorption, while glutinous rice absorbs iodine.