Rice is a cereal grain, and in its domesticated form is the staple food for over half of the world's human population, particularly in Asia and Africa, due to the vast amount of soil that is able to grow rice. Rice is the seed of the grass species Oryza sativa or, much less commonly, O. glaberrima. Asian rice was domesticated in China some 13,500 to 8,200 years ago, while African rice was domesticated in Africa some 3,000 years ago. Rice has become commonplace in many cultures worldwide; in 2021, 787 million tons were produced, placing it fourth after sugarcane, maize, and wheat. Only some 8% of rice is traded internationally. China, India, and Indonesia are the largest consumers of rice. A substantial amount of the rice produced in developing nations is lost after harvest through factors such as poor transport and storage. Rice yields can be reduced by pests including insects, rodents, and birds, as well as by weeds, and by diseases such as rice blast. Traditional polycultures such as rice-duck farming, and modern integrated pest management seek to control damage from pests in a sustainable way.
Domestication is a multi-generational mutualistic relationship between humans and other organisms, in which humans took over control and care to obtain a steady supply of resources including food. The process was gradual and geographically diffuse, based on trial and error.
Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Introgression is a long-term process, even when artificial; it may take many hybrid generations before significant backcrossing occurs. This process is distinct from most forms of gene flow in that it occurs between two populations of different species, rather than two populations of the same species.
Oryza rufipogon, known as brownbeard rice, wild rice, and red rice, is a member of the genus Oryza.
Oryza longistaminata is a perennial species of grass from the same genus as cultivated rice. It is native to most of sub-Saharan Africa and Madagascar. It has been introduced into the United States, where it is often regarded as a noxious weed. Its common names are longstamen rice and red rice.
A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon.
Oryza glaberrima, commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown in West Africa around 3,000 years ago. In agriculture, it has largely been replaced by higher-yielding Asian rice, and the number of varieties grown is declining. It still persists, making up an estimated 20% of rice grown in West Africa. It is now rarely sold in West African markets, having been replaced by Asian strains.
Oryza nivara is a wild progenitor of the cultivated rice Oryza sativa. It is found growing in swampy areas, at edge of pond and tanks, beside streams, in ditches, in or around rice fields. Grows in shallow water up to 0.3 metres, in seasonally dry and open habitats.
Japonica rice, sometimes called sinica rice, is one of the two major domestic types of Asian rice varieties. Japonica rice is extensively cultivated and consumed in East Asia, whereas in most other regions indica rice is the dominant type of rice. Japonica rice originated from Central China, where it was first domesticated along the Yangtze River basin approximately 9,500 to 6,000 years ago.
Rice production in China is the amount of rice planted, grown, and harvested for consumption in the mainland of China.
Perennial rice are varieties of long-lived rice that are capable of regrowing season after season without reseeding; they are being developed by plant geneticists at several institutions. Although these varieties are genetically distinct and will be adapted for different climates and cropping systems, their lifespan is so different from other kinds of rice that they are collectively called perennial rice. Perennial rice—like many other perennial plants—can spread by horizontal stems below or just above the surface of the soil but they also reproduce sexually by producing flowers, pollen and seeds. As with any other grain crop, it is the seeds that are harvested and eaten by humans.
Plant breeding is the science of changing the traits of plants in order to produce desired characteristics. It has been used to improve the quality of nutrition in products for humans and animals. The goals of plant breeding are to produce crop varieties that boast unique and superior traits for a variety of applications. The most frequently addressed agricultural traits are those related to biotic and abiotic stress tolerance, grain or biomass yield, end-use quality characteristics such as taste or the concentrations of specific biological molecules and ease of processing.
Plant breeding started with sedentary agriculture, particularly the domestication of the first agricultural plants, a practice which is estimated to date back 9,000 to 11,000 years. Initially, early human farmers selected food plants with particular desirable characteristics and used these as a seed source for subsequent generations, resulting in an accumulation of characteristics over time. In time however, experiments began with deliberate hybridization, the science and understanding of which was greatly enhanced by the work of Gregor Mendel. Mendel's work ultimately led to the new science of genetics. Modern plant breeding is applied genetics, but its scientific basis is broader, covering molecular biology, cytology, systematics, physiology, pathology, entomology, chemistry, and statistics (biometrics). It has also developed its own technology. Plant breeding efforts are divided into a number of different historical landmarks.
Rajeev Kumar Varshney is an Indian agricultural scientist, specializing in genomics, genetics, molecular breeding and capacity building in developing countries. Varshney is currently serving as Director, Western Australian State Agricultural Biotechnology Center; Director, Centre for Crop & Food Innovation; and International Chair in Agriculture & Food Security with the Food Futures Institute at Murdoch University, Australia since Feb 2022. Before joining Murdoch University, Australia he served International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), a global agriculture R&D institute, for more than 16 years in different scientific and research leadership roles including Research Program Director for three global research programs– Grain Legumes, Genetic Gains and Accelerated Crop Improvement Program. He has the onus of establishing and nurturing the Center of Excellence in Genomics & Systems Biology (CEGSB), a globally recognized center for genomics research at ICRISAT that made impacts on improving agriculture and development of human resources in several countries including India, China, Kenya, Ethiopia, Tanzania, Nigeria, Ghana, Mali, Senegal, Burkina Faso, etc. Varshney holds Adjunct/Honorary/Visiting Professor positions at 10 academic institutions in Australia, China, Ghana, Hong Kong and India, including The University of Western Australia, University of Queensland, West Africa Centre for Crop Improvement, University of Hyderabad, Chaudhary Charan Singh University and Professor Jayashankar Telangana State Agricultural University.
Xanthomonas oryzae pv. oryzae is a bacterial pathovar that causes a serious blight of rice, other grasses, and sedges.
Domestication syndrome refers to two sets of phenotypic traits that are common to either domesticated plants or domesticated animals.
A plant genome assembly represents the complete genomic sequence of a plant species, which is assembled into chromosomes and other organelles by using DNA fragments that are obtained from different types of sequencing technology.
The history of rice cultivation is an interdisciplinary subject that studies archaeological and documentary evidence to explain how rice was first domesticated and cultivated by humans, the spread of cultivation to different regions of the planet, and the technological changes that have impacted cultivation over time.
The agricultural weed syndrome is the set of common traits which make a plant a successful agricultural weed. Most of these traits are not, themselves, phenotypes but are instead methods of rapid adaptation. So equipped, plants of various origins - invasives, natives, mildly successful marginal weeds of agriculture, weeds of other settings - accumulate other characteristics which allow them to compete in an environment with a high degree of human management.
