El origen africano del cultivo de arroz en las Américas / The african origins of rice cultivation in the Americas

El arroz no empezó a ser cultivado en las Américas sino hasta el periodo del comercio transatlántico de esclavos. Para el siglo XVIII este cultivo ya se había establecido extensamente en plantaciones desde Carolina del Sur hasta Brasil. Cultivado por esclavos así como cimarrones, tanto para la subsistencia como para la exportación, el comienzo de la cultivación de arroz en las Américas invariablemente se ha atribuido a los dueños de plantaciones europeos. Este artículo presenta evidencia del importante papel que desempeñaron los africanos en establecer la cultura del arroz en el Nuevo Mundo. Este trabajo se enfoca sobre el arroz africano (Oryza glaberrima), personas esclavizadas de África occidental para quienes este cultivo era un alimento básico, y un sistema de conocimiento indígena sobre el arroz con características idénticas entre el Atlántico africano y americano. Un estudio comparativo de usos del suelo, métodos de cultivo, procesos de molienda y tradiciones culinarias ilumina el tema de la difusión de la cultura africana de arroz a las Américas, así como la labor que desempeñaron los esclavos de África occidental en liderar el cultivo de arroz para eventualmente convertirlo en un alimento básico de subsistencia en el Nuevo Mundo (AU)

Until the period of the transatlantic slave trade, rice was not cultivated in the Americas. By the eighteenth century the crop was widely established across plantation societies from South Carolina to Brazil. Grown by slaves as well as maroons, for subsistence and also for export, the onset of rice cultivation in the Americas has long been attributed to European planters. This article presents evidence that supports African agency in establishing rice culture in the New World. Emphasis is on African rice (Oryza glaberrima), enslaved West Africans for whom the crop was a dietary staple, and an indigenous rice knowledge system with identical features across the African and American Atlantic. A comparative analysis of land use, methods of cultivation, milling and cooking traditions illuminates the diffusion of African rice culture to the Americas and the role of West African slaves in pioneering rice as a New World subsistence staple (AU)

Chinese rice production area adaptations to climate changes, 1949-2010.

Climate change has great impact on cropping system. Understanding how the rice production system has historically responded to external forces, both natural and anthropogenic, will provide critical insights into how the system is likely to respond in the future. The observed historic rice movement provides insights into the capability of the rice production system to adapt to climate changes. Using province-level rice production data and historic climate records, here we show that the centroid of Chinese rice production shifted northeastward over 370 km (2.98°N in latitude and 1.88°E in longitude) from 1949 to 2010. Using a linear regression model, we examined the driving factors, in particular climate, behind such rice production movement. While the major driving forces of the rice relocation are such social economic factors as urbanization, irrigation investment, and agricultural or land use policy changes, climate plays a significant role as well. We found that temperature has been a significant and coherent influence on moving the rice center in China and precipitation has had a significant but less spatially coherent influence.

Archaeological and genetic insights into the origins of domesticated rice.

Rice (Oryza sativa) is one of the most important cereal grains in the world today and serves as a staple food source for more than half of the world's population. Research into when, where, and how rice was brought into cultivation and eventually domesticated, along with its development into a staple food source, is thus essential. These questions have been a point of nearly continuous research in both archaeology and genetics, and new information has continually come to light as theory, data acquisition, and analytical techniques have advanced over time. Here, we review the broad history of our scientific understanding of the rice domestication process from both an archaeological and genetic perspective and examine in detail the information that has come to light in both of these fields in the last 10 y. Current findings from genetics and archaeology are consistent with the domestication of O. sativa japonica in the Yangtze River valley of southern China. Interestingly, although it appears rice was cultivated in the area by as early 8000 BP, the key domestication trait of nonshattering was not fixed for another 1,000 y or perhaps longer. Rice was also cultivated in India as early as 5000 BP, but the domesticated indica subspecies currently appears to be a product of the introgression of favorable alleles from japonica. These findings are reshaping our understanding of rice domestication and also have implications for understanding the complex evolutionary process of plant domestication.

Single rice growth period was prolonged by cultivars shifts, but yield was damaged by climate change during 1981-2009 in China, and late rice was just opposite.

Based on the crop trial data during 1981-2009 at 57 agricultural experimental stations across the North Eastern China Plain (NECP) and the middle and lower reaches of Yangtze River (MLRYR), we investigated how major climate variables had changed and how the climate change had affected crop growth and yield in a setting in which agronomic management practices were taken based on actual weather. We found a significant warming trend during rice growing season, and a general decreasing trend in solar radiation (SRD) in the MLRYR during 1981-2009. Rice transplanting, heading, and maturity dates were generally advanced, but the heading and maturity dates of single rice in the MLRYR (YZ_SR) and NECP (NE_SR) were delayed. Climate warming had a negative impact on growth period lengths at about 80% of the investigated stations. Nevertheless, the actual growth period lengths of YZ_SR and NE_SR, as well as the actual length of reproductive growth period (RGP) of early rice in the MLRYR (YZ_ER), were generally prolonged due to adoption of cultivars with longer growth period to obtain higher yield. In contrast, the actual growth period length of late rice in the MLRYR (YZ_LR) was shortened by both climate warming and adoption of early mature cultivars to prevent cold damage and obtain higher yield. During 1981-2009, climate warming and decrease in SRD changed the yield of YZ_ER by -0.59 to 2.4%; climate warming during RGP increased the yield of YZ_LR by 8.38-9.56%; climate warming and decrease in SRD jointly reduced yield of YZ_SR by 7.14-9.68%; climate warming and increase in SRD jointly increased the yield of NE_SR by 1.01-3.29%. Our study suggests that rice production in China has been affected by climate change, yet at the same time changes in varieties continue to be the major factor driving yield and growing period trends.

The dual Green Revolutions in South Korea: reforestation and agricultural revolution under the authoritarian regime.

In South Korea, the Green Revolution has been commonly understood as the development and dissemination of new rice varieties ('Tongil' rice) and the rapid increase of rice yield in the 1970s. However, revolutionary success in agriculture was not the only green revolution South Korea experienced; another green revolution lay in the success of reforestation projects. In the 1970s, South Korea's forest greening was closely related to its agricultural revolution in several ways. Therefore, South Korea's Green Revolution was an intrinsically linked double feature of agriculture and forestry. This two-pronged revolution was initiated by scientific research - yet accomplished by the strong administrative mobilization of President Park Chung Hee's regime. The process of setting goals and meeting them through a military-like strategy in a short time was made possible under the authoritarian regime, known as 'Yushin', though the administration failed to fully acknowledge scientific expertise in the process of pushing to achieve goals.

Composite farming systems in an era of change: Nagaland, Northeast India.

Composite farming systems, first clearly identified by Rambo, are those in which radically different technologies are found together in a single farming complex. Data from diaries kept by groups of farming families in two Angami Naga villages in northeast India, Khonoma and smaller Tsiesema, detailing inputs into and outputs from wet-rice terraces and jhum (swidden) fields in the years 2000 and 2001, are presented and discussed to detail the workings of related but different composite systems. The 2000­2001 survey caught an important set of changes in midstream. Although returns to labour from the first-year jhums were much higher than those from the wet-rice terraces in 2000­2001, jhums were declining in significance as a growing non-farm economy joined the production of cool-climate vegetables and a spice crop for the Indian market as principal sources of livelihood. This story is told in the light of recent writing on the demise of swidden in the larger Southeast Asian region, and it is suggested that greater attention be paid to the composite systems, which are not uncommon in this region. This might help diversify what has perhaps been an oversimplified discussion.

Molecular evidence for a single evolutionary origin of domesticated rice.

Asian rice, Oryza sativa, is one of world's oldest and most important crop species. Rice is believed to have been domesticated ∼9,000 y ago, although debate on its origin remains contentious. A single-origin model suggests that two main subspecies of Asian rice, indica and japonica, were domesticated from the wild rice O. rufipogon. In contrast, the multiple independent domestication model proposes that these two major rice types were domesticated separately and in different parts of the species range of wild rice. This latter view has gained much support from the observation of strong genetic differentiation between indica and japonica as well as several phylogenetic studies of rice domestication. We reexamine the evolutionary history of domesticated rice by resequencing 630 gene fragments on chromosomes 8, 10, and 12 from a diverse set of wild and domesticated rice accessions. Using patterns of SNPs, we identify 20 putative selective sweeps on these chromosomes in cultivated rice. Demographic modeling based on these SNP data and a diffusion-based approach provide the strongest support for a single domestication origin of rice. Bayesian phylogenetic analyses implementing the multispecies coalescent and using previously published phylogenetic sequence datasets also point to a single origin of Asian domesticated rice. Finally, we date the origin of domestication at ∼8,200-13,500 y ago, depending on the molecular clock estimate that is used, which is consistent with known archaeological data that suggests rice was first cultivated at around this time in the Yangtze Valley of China.

Is international agricultural research a global public good? The case of rice biofortification.

The status of international agricultural research as a global public good (GPG) has been widely accepted since the Green Revolution of the 1960s and 1970s. While the term was not used at the time of its creation, the Consultative Group on International Agricultural Research (CGIAR) system that evolved at that time has been described as a 'prime example of the promise, performance and perils of an international approach to providing GPGs'. Contemporary literature on international agricultural research as a GPG tends to support this view and focuses on how to operationalize the concept. This paper adopts a different starting point and questions this conceptualization of the CGIAR and its outputs. It questions the appropriateness of such a 'neutral' concept to a system born of the imperatives of Cold War geopolitics, and shaped by a history of attempts to secure its relevance in a changing world. This paper draws on a multi-sited, ethnographic study of a research effort highlighted by the CGIAR as an exemplar of GPG-oriented research. Behind the ubiquitous language of GPGs, 'partnership' and 'consensus', however, new forms of exclusion and restriction are emerging within everyday practice, reproducing North-South inequalities and undermining the ability of these programmes to respond to the needs of projected beneficiaries.

Late Holocene methane rise caused by orbitally controlled increase in tropical sources.

Considerable debate surrounds the source of the apparently 'anomalous' increase of atmospheric methane concentrations since the mid-Holocene (5,000 years ago) compared to previous interglacial periods as recorded in polar ice core records. Proposed mechanisms for the rise in methane concentrations relate either to methane emissions from anthropogenic early rice cultivation or an increase in natural wetland emissions from tropical or boreal sources. Here we show that our climate and wetland simulations of the global methane cycle over the last glacial cycle (the past 130,000 years) recreate the ice core record and capture the late Holocene increase in methane concentrations. Our analyses indicate that the late Holocene increase results from natural changes in the Earth's orbital configuration, with enhanced emissions in the Southern Hemisphere tropics linked to precession-induced modification of seasonal precipitation. Critically, our simulations capture the declining trend in methane concentrations at the end of the last interglacial period (115,000-130,000 years ago) that was used to diagnose the Holocene methane rise as unique. The difference between the two time periods results from differences in the size and rate of regional insolation changes and the lack of glacial inception in the Holocene. Our findings also suggest that no early agricultural sources are required to account for the increase in methane concentrations in the 5,000 years before the industrial era.

The tyranny of taste: the case of organic rice in Cambodia.

Fair-trade and organic products are often sold at price premiums justified by smaller production volumes that are associated with greater social and environmental responsibility. The consumption of these products confers on the consumer a greater sense of morality ­ and usually a claim to better taste. This paper tells the story of attempts to promote organic/fair-trade rice production by de facto organic Cambodian farmers for export to North American and European markets in order to assist poor farmers to trade their way out of poverty. It demonstrates that instead of promoting sustainable agriculture and fair trade between developed and developing markets, organic/fair-trade projects may impose First World consumer ideals and tastes that are out of step with the larger realities of agrarian transition in Cambodia and the wider region of developing Southeast Asia.

One grain, one nation: rice genetics and the corporate state in early Francoist Spain (1939­1952.

This paper aims to show the links between rice genetics and the corporatist political economy of early Francoism. After investigating the transition from prewar rice producers' associations to a new federation embedded in a vertical union, I identify three main novelties of the new organization: its national scope, its need to address lack of supply rather than overproduction, and its hierarchical functioning. I then focus on the one state-owned agricultural station devoted to rice research, showing how its agricultural scientists shaped, and relied on, the state-controlled unions, both for producing and distributing new varieties of rice and for controlling the seeds farmers used. Finally, I explore how this relationship made it possible for the scientists to test, multiply, and distribute throughout the Spanish landscape the seeds they produced at the laboratory, thus putting hierarchical unity and autarky to work and demonstrating the role of scientists as active agents of state formation and landscape transformation within a corporatist political economy.

Understanding the evolution of rice technology in China - from traditional agriculture to GM rice today.

This paper provides an historical survey of the evolution of rice technology in China, from the traditional farming system to genetically modified rice today. Using sociotechnological analytical framework, it analyses rice technology as a socio-technical ensemble - a complex interaction of material and social elements, and discusses the specificity of technology development and its socio-technical outcomes. It points to two imperatives in rice variety development: wholesale transporting agricultural technology and social mechanism to developing countries are likely lead to negative consequences; indigenous innovation including deploying GM technology for seed varietal development and capturing/cultivating local knowledge will provide better solutions.

Selection on grain shattering genes and rates of rice domestication.

Molecular cloning of major quantitative trait loci (QTLs) responsible for the reduction of rice grain shattering, a hallmark of cereal domestication, provided opportunities for in-depth investigation of domestication processes. Here, we studied nucleotide variation at the shattering loci, sh4 and qSH1, for cultivated rice, Oryza sativa ssp. indica and Oryza sativa ssp. japonica, and the wild progenitors, Oryza nivara andOryza rufipogon. The nonshattering sh4 allele was fixed in all rice cultivars, with levels of sequence polymorphism significantly reduced in both indica and japonica cultivars relative to the wild progenitors. The sh4 phylogeny together with the neutrality tests and coalescent simulations suggested that sh4 had a single origin and was fixed by artificial selection during the domestication of rice. Selection on qSH1 was not detected in indica and remained unclear in japonica. Selection on sh4 could be strong enough to have driven its fixation in a population of cultivated rice within a period of c. 100 yr. The slow fixation of the nonshattering phenotype observed at the archeological sites might be a result of relatively weak selection on mutations other than sh4 in early rice cultivation. The fixation of sh4 could have been achieved later through strong selection for the optimal phenotype.

The molecular bases of cereal domestication and the history of rice.

In this review, we discuss the development of molecular genetics and genomics that has allowed one to identify and characterize some of the key genes involved in cereal domestication. The list is far from being complete, but the first conclusion that can be drawn from the published works is that only a few loci have been the target of human selection in the first stages of the domestication process at the late neolithic. Mutations at these few loci have led to dramatic changes in plant morphology and phenology, transforming a wild into a cultivated plant. We also show that in the case of rice, for which the complete genome sequence is available, the development of new molecular markers based on retrotransposon insertion polymorphisms helped to resolve some of the questions regarding the origin of the domestication of the crop in Asia.

Fire and flood management of coastal swamp enabled first rice paddy cultivation in east China.

The adoption of cereal cultivation was one of the most important cultural processes in history, marking the transition from hunting and gathering by Mesolithic foragers to the food-producing economy of Neolithic farmers. In the Lower Yangtze region of China, a centre of rice domestication, the timing and system of initial rice cultivation remain unclear. Here we report detailed evidence from Kuahuqiao that reveals the precise cultural and environmental context of rice cultivation at this earliest known Neolithic site in eastern China, 7,700 calibrated years before present (cal. yr bp). Pollen, algal, fungal spore and micro-charcoal data from sediments demonstrate that these Neolithic communities selected lowland swamps for their rice cultivation and settlement, using fire to clear alder-dominated wetland scrub and prepare the site for occupation, then to maintain wet grassland vegetation of paddy type. Regular flooding by slightly brackish water was probably controlled by 'bunding' to maintain crop yields. The site's exploitation ceased when it was overwhelmed by marine inundation 7,550 cal. yr bp. Our results establish that rice cultivation began in coastal wetlands of eastern China, an ecosystem vulnerable to coastal change but of high fertility and productivity, attractions maximized for about two centuries by sustained high levels of cultural management of the environment.

Different patterns of genealogical relationships found in the two major QTLs causing reduction of seed shattering during rice domestication.

The three quantitative trait loci (qSH1, qSH3, and qSH4) causing reduction of seed shattering were investigated to examine their relative importance during rice domestication. The qSH1 and qSH4 loci showed a distinct effect on the reduction of shattering, compared with the qSH3 locus. Fine mapping and sequence analysis strongly suggested that the qSH1 and qSH4 loci are the same as the recently reported genes. A non-shattering allele at qSH1 drastically changed the shattering phenotype to a non-shattering phenotype even in the presence of shattering alleles at the qSH3 and qSH4 loci, showing that qSH1 is genetically epistatic to the other loci. The level of the reduction in sequence diversity was compared between the qSH1 and qSH4 regions. The sequence diversity was severely reduced in the qSH1 region of Oryza sativa subsp. japonica compared with that of O. sativa subsp. indica, despite that the level of diversity was similarly reduced at the qSH4 region in the 2 subspecies. Phylogenetic reconstruction based on the combined sequences of the flanking sites showed different patterns in the 2 subspecies. The 2 subspecies formed a single clade with respect to qSH4, whereas they were separated into different lineages with respect to qSH1, suggesting that these loci had different histories during rice domestication.

An SNP caused loss of seed shattering during rice domestication.

Loss of seed shattering was a key event in the domestication of major cereals. We revealed that the qSH1 gene, a major quantitative trait locus of seed shattering in rice, encodes a BEL1-type homeobox gene and demonstrated that a single-nucleotide polymorphism (SNP) in the 5' regulatory region of the qSH1 gene caused loss of seed shattering owing to the absence of abscission layer formation. Haplotype analysis and association analysis in various rice collections revealed that the SNP was highly associated with shattering among japonica subspecies of rice, implying that it was a target of artificial selection during rice domestication.