Early Rice Cultivation Research Articles

Delayed Sowing under the Same Transplanting Date Shortened the Growth Period of Machine-Transplanted Early-Season Rice with No Significant Yield Reduction Caused

In early rice cultivation, the age of seedlings plays a crucial role in ensuring the annual safety production of double-cropping rice. When sowing staging and transplanting are performed simultaneously, it is still necessary to gather more data about the effects of seedling age on the growth period and grain yield of early rice machines transplanted. Two years ago, field experiments were conducted on machine-transplanted rice seedlings in the early season to compare the growth duration, crop growth characteristics, and yield attributes between the 18-day-old seedlings (SA18) and 32-day-old seedlings (SA32) of two rice cultivars. As a result of the study, it was found that SA18 reduced the total crop duration by between 11 and 12 days but delayed the maturity date by 2–3 days compared to SA32. SA18 had 14.5% fewer panicles per m2 and 3.6% less harvest index but 7.5% more spikelets per panicle higher than SA32. The grain yield of SA18 was 3.4% less than that of SA32, but there was no significant difference between the two seedling ages. The machine-transplanted seedlings for early rice production are more efficient in reducing seedling management time without affecting harvesting time and yields. The authors provide a new cultivation management scheme for farmers who are interested in planting double-cropping rice at the same time.

The origins of multi-cropping agriculture in Southwestern China: Archaeobotanical insights from third to first millennium B.C. Yunnan

Yunnan’s location at the crossroad of temperate China, Northeast India and tropical mainland Southeast Asia makes it a pivotal area for the understanding of early cultural contacts and agricultural spread between these ecologically diverse regions. This paper evaluates current evidence relating to the emergence of the first agricultural systems in Yunnan. It also reviews previous theories on agricultural dispersal to Yunnan, including whether Austroasiatic speakers were responsible for the spread of rice from Yunnan to mainland Southeast Asia, and builds a new framework that allows to tie agricultural development in the region into broader patterns of early migration and exchange networks. Archaeobotanical remains attest to an initial spread of rice and millet from Central China into Yunnan in the third millennium B.C. and the establishment of a mixed-crop economy; the introduction of wheat and barley in the second millennium B.C. allowed for increased diversification of the agricultural system, with a two-season intensification trend in the late first millennium B.C. Differences in early rice cultivation ecologies between Yunnan and mainland Southeast Asia suggest that Yunnan rice farmers may not have had a primary role in the southern dispersal of rice, however, more data is needed to fully clarify the source and development of dryland cultivation of rice in mainland Southeast Asia.

Excavation at Hanjing site yields evidence of early rice cultivation in the Huai River more than 8000 years ago

Excavation at Hanjing site yields evidence of early rice cultivation in the Huai River more than 8000 years ago

Climate and landscape change favouring early rice agriculture and appreciable human impact: Evidence from sediment [formula omitted]13C in eastern China

Kuahuqiao site, famous for its early rice cultivation, is taken to be a typical case of how agriculture emerged in a littoral environment in the early Holocene. However, the lack of fire history and local climatic reconstruction has hindered the detailed picture of agricultural origins and development. Here we report new records of TOC, BC, δ13CTOC, δ13CBC, and C/N, alongside published pollen and charcoal data. Our δ13CTOC and C/N confirm the previously-proposed formation of wetlands, which offered favorable landscapes for rice paddy agriculture, prior to the appearance of the Kuahuqiao culture. Based on BC, δ13CTOC, and δ13CBC records we suggest a hotter but drier climate that would have benefited rice agriculture by augmenting the distribution of wild rice and C4 herbs. In addition, δ13CTOC shows a decreased C3/C4 ratio as a signal of human occupation with manipulation of forest for hunting-gathering or/and land clearance for agriculture. Combined δ13CBC and BC records oppose the proposal of intense fire use in early agriculture and suggest that fire use was constrained to domestic purposes. Flood events which seem to have terminated the Kuahuqiao culture left impressions in TOC, BC, δ13CTOC, δ13CBC.

Artificial selection in the expansion of rice cultivation.

Gene distributions and population genomics suggest artificial selection of ghd7 osprr37, for extremely early heading date of rice, in the Tohoku region of Japan. The ranges of cultivated crops expanded into various environmental conditions around the world after their domestication. Hokkaido, Japan, lies at the northern limit of cultivation of rice, which originated in the tropics. Novel genotypes for extremely early heading date in Hokkaido are controlled by loss-of-function of both Grain number, plant height and heading date 7 (Ghd7) and Oryza sativa Pseudo-Response Regulator 37 (OsPRR37). We traced genotypes for extremely early heading date and analyzed the phylogeny of rice varieties grown historically in Japan. The mutations in Ghd7 and OsPRR37 had distinct local distributions. Population genomics revealed that varieties collected from the Tohoku region of northern Japan formed three clusters. Mutant alleles of Ghd7 and OsPRR37 appear to have allowed rice cultivation to spread into Hokkaido. Our results show that the mutations of two genes might be occurred in the process of artificial selection during early rice cultivation in the Tohoku region.

The effect of early season rice varieties and establishment methods on greenhouse gas emissions in southeast China

Methane (CH4) and nitrous oxide (N2O) emissions from rice fields are considered to be important sources of greenhouse gases. In order to clarify the emission characteristics of CH4 and N2O at different growth stages and to find optimal early season rice varieties and cultivation methods to control greenhouse gas emissions in southeast China, we conducted research in Jinhua City, Zhejiang Province, China in 2017 and 2018. Four different early season rice varieties were planted using three different rice establishment methods (machine transplanting, artificial transplanting, and direct seeding). The grain yield, CH4, and N2O emission rates and flux and economic profit were compared between the early varieties and establishment methods. Our results show that during the rice growth period, the CH4 and N2O emission fluxes and emission rates of the early season rice varieties increased first and then decreased, reaching the maximum at booting and the minimum at the grain filling stage. Direct seeding had the lowest cost and emission fluxes and emission rates compared to machine transplanting and artificial transplanting. The emission rates and flux of ‘Zhuliangyou609’ and ‘Zhongjiazao17’ were lower than in the other varieties. However, the yield of ‘Zhuliangyou609’ was higher than that of ‘Zhongjiazao17’ under identical conditions. Hence, direct-seeded rice shows good potential for cultivation in Zhejiang Province, and ‘Zhuliangyou609’ is the optimal early variety. This study provides theoretical support for the development of environmentally friendly early season rice establishment methods in southeast China.

Increases in Genetic Diversity of Weedy Rice Associated with Ambient Temperatures and Limited Gene Flow.

Simple SummaryIncreased genetic diversity in plants is probably associated with greater ambient temperatures. To test this hypothesis, we studied genetic diversity and differentiation of weedy rice populations occurring in the early- and late-season rice cultivation fields in Leizhou of southern China. Data collected from 10-year climatic records showed a higher average temperature in the late rice-cultivation seasons than in the early rice-cultivation seasons. Results obtained based on 27 SSR (simple sequence repeat) loci indicated greater genetic diversity in the late-season weedy rice populations, in addition to the considerable genetic differentiation between the early- and late-season weedy rice populations. We therefore conclude that a higher ambient temperature might be an important factor to promote the formation of genetic diversity in the late-season weedy rice populations.Hypotheses regarding the association of increased species or genetic diversity with gradually warmer regions as a global pattern have been proposed, but no direct and solid experimental data are available to approve the association between plant genetic diversity and ambient temperatures. To test the diversity-temperature hypothesis, we studied genetic diversity and genetic differentiation of weedy rice (Oryza sativa f. spontanea) populations occurring naturally in early- and late-season rice fields that share nearly the same ecological conditions but with slightly different temperatures. Data collected from 10-year historical climatic records indicated a ~2 °C higher average air temperature in the late rice-cultivation seasons than in the early seasons. Results based on molecular fingerprints of 27 SSR (simple sequence repeat) loci showed a higher level of genetic diversity in the late-season weedy rice populations than in the early-season populations. In addition, a positive correlation was detected between the increased proportion of genetic diversity (ΔHe) and genetic differentiation among the weedy rice populations, suggesting limited gene flow. Therefore, we conclude from this study that increased genetic diversity in the late-season weedy rice populations is probably caused by the higher ambient temperatures. This finding provides evidence for the possible association between genetic diversity and ambient temperatures.

Early to middle Holocene rice cultivation in response to coastal environmental transitions along the South Hangzhou Bay of eastern China

South Hangzhou Bay (SHB) in eastern China is one of the regions where agriculture began in the early Holocene. To better understand how farming-based societies developed in this region, we examined pollen, charcoal, foraminifera and grain size information of a well-dated sediment core (YJ1503) in the Yaojiang Valley (YJV). Pollen assemblages show that before 8600 cal yr BP, Pinus, Quercus, Juglans and Pterocarya woodlands were dominant. During ca.8600–8400 cal yr BP, abundant foraminifera suggest a transient marine incursion. Although the former woodland species re-established during 8400–7600 cal yr BP, freshwater algae and dinoflagellates indicate a transition to brackish environments. Two peaks of charcoal at around 8200 and 7800 cal yr BP, are possible early signs of human occupation that pre-dated the Hemudu Culture. After 7600 cal yr BP, an increase of salt-tolerant herbs including Chenopodiaceae, Cyperaceae and Poaceae (<35 μm) and a decrease of dinoflagellate and foraminifera assemblages, imply a reduction in saline influence. Freshwater wetlands established around 6600 cal yr BP as indicated by increasing Typha and diminishing Chenopodiaceae pollen. This coincided with a sharp decline in Pinus pollen, marked increases of Poaceae pollen and a rise in charcoal suggesting more activity of human communities. Rice cultivation is confirmed by archaeological findings from this interval, with two distinctive periods at ca. 6600–6300 and 5500–5200 cal yr BP. The initial coastal land development started as early as 7800–7600 cal yr BP in the YJV, which was concurrent with that happened at the apex of SHB where the Kuahuqiao Culture originated, but rice farming trajectory at these two places differed. In the Kuahuqiao area, low salinity coastal settings developed, freshened by the discharge of the Qiantang River,and this area would have been especially suitable for agriculture. In contrast, in the YJV, early rice cultivation was possibly hampered by longer episodes of brackish intrusion during time of lower discharge of the Yaojiang River until a freshwater environment prevailed after ca. 7000 cal yr BP.

Were chickens exploited in the Neolithic early rice cultivation society of the lower Yangtze River?

The origins of chicken (Gallus gallus domesticus) domestication have remained debatable for over a century. China, and particularly northern China, has been claimed as one of the early centers for the domestication of chickens, because many alleged chicken bones have been discovered at a number of archeological sites. However, the identification of archeological domestic chicken bones from early Holocene sites in northern China remains contentious. The Neolithic chicken exploitation in southern China close to modern distribution area of wild red junglefowl (G. gallus) remained unclear, since analyses of bird bones were scarce in the region. To reveal the birds, especially chicken, exploitation in Neolithic southern China, we analyzed bird remains from Tianluoshan site which is located in the lower Yangtze River and is a ruin of large village in the Neolithic early rice cultivation society. Ducks (Anatinae), rails (Rallidae), and geese/swans (Anserinae) were dominant, suggesting that peoples in the Tianluoshan site got birds at inland and brackish waters environments near the site. Although two G. gallus size bones were found at the site, it is also included in the size range of five indigenous pheasants in the region and further studies are required for the species identification of the bones. Phasianidae bones occupied only 0.4% of NISP, suggesting Phasianidae birds, including domestic chickens and red junglefowls, were rarely exploited in the Tianluoshan site. The results did not support the north-word expanded wild distribution of red junglefowl nor early Holocene chicken exploitation in the lower Yangtze River.

New insights into the grinding tools used by the earliest farmers in the central plain of China

The site of Jiahu in the central plain of China is known for its early rice cultivation 9000 years ago. The preliminary starch analysis implies that the Jiahu grinding tools were used for processing various plants, including rice. This paper presents the use-wear analysis carried out on a sample of seventeen grinding tools from Jiahu, nine of which were previously analyzed for the presence of starch. Use-wear traces associated with processing cereal and wood-like material were identified. This result confirms important evidence of cereal processing in the early Neolithic period. It also reveals the diversity of functions in the grinding tool assemblage. Furthermore, the use-wear distribution indicates that grinding slabs without feet and cylindrical rollers were mainly associated with the processing of cereals while grinding slabs with feet were mainly related to the processing of wood-like material. Quantitative analysis of the starch data also indicates that grinding slabs without feet possess more starch grains than the grinding slabs with feet. Therefore, it is argued that specific types of grinding tools were used for processing specific kinds of material. This study highlights the different roles grinding tools may have played in early farming societies.

Early agriculture in Sri Lanka: New Archaeobotanical analyses and radiocarbon dates from the early historic sites of Kirinda and Kantharodai (Kandarodai)

Archaeobotanical evidence from two Early Historic sites in Sri Lanka, Kantharodai and Kirinda, is reported, providing significant evidence for agricultural diversity beyond the cultivation of rice. These data highlight the potential of systematic archaeobotanical sampling for macro-remains in tropical environments to contribute to the understanding of subsistence history in the tropics. Direct AMS radiocarbon dating confirms both the antiquity of crops and refines site chronologies. Both sites have Oryza sativa subsp. indica rice and evidence of rice crop-processing and millet farming. In addition, phytolith data provide complementary evidence on the nature of early rice cultivation in Sri Lanka. Both Kantharodai and Kirinda possess rice agriculture and a diverse range of cultivated millets (Brachiaria ramosa, Echinochloa frumentacea, Panicum sumatrense, and Setaria verticillata). Pulses of Indian origin were also cultivated, especially Vigna radiata and Macrotyloma uniflorum. Cotton (Gossypium sp.) cultivation is evident from Kirinda. Both sites, but in particular Kirinda, provide evidence for use of the seeds of Alpinia sp., in the cardamom/ginger family (Zingiberaceae), a plausible wild spice, while coconuts (Cocos nucifera) were also found at Kirinda.

한중일 반월형석도 비교 연구

This paper aims to compare the archaeological stone harvesting knives from Korea, China, and Japan. First, harvesting knives of the Misari assemblage, the first crop cultivation culture in Korea, is characterized by the rectangular shape and double-edged blade. This feature is also observed in the Duman and Amnok river basins in North Korea, while in China it is found only in the Liaodong mountain area represented by the Machengzi culture. However, in detail, only one example form China has a double-edged blade so this feature is probably selected when they adopt stone harvesting knives in the Korean Peninsula. Second, the materials from the Shang-Zhou period in the Shandong area were examined, considering the origin of Songguk-ri culture. While comb shape is dominant in this assemblage, more importantly, stone harvesting knives disappeared in this phase. This situation is totally different from that of the Korean Bronze Age, where they had developed a new triangle shape according to the development of wet rice cultivation. It is difficult to deny the possibility of the interaction between Korea and the Shandong area, in spite of the difference in the number of stone knives as the former had it already in the previous phase. Finally, both grooving and perforated type and two-hole type appeared in the northern Kyushu area. Generally, they are boat shape and double edged, while no triangle shape has been found. This indicates early rice cultivation diffused to northern Kyushu before the appearance of triangle shape in the Korean peninsula. This difference show a similar pattern to that was observed between the Machengzi culture and Misari assemblage. Probably multifunctional double edged knives were preferred when they introduced crop cultivation.

Pathways of Rice Diversification across Asia

The archaeology of rice has made important methodological advances over the past decade that have contributed new data on the domestication process, spread and ecology of cultivation. Growing evidence from spikelet bases indicates that non-shattering, domesticated forms evolved gradually in the Yangtze basin and that there were at least two distinct processes around the Middle Yangtze region pre-dating 6000 BC, and the in the Lower Yangtze region between 6000 and 4000 BC. Early rice cultivation in these areas was based on wet field ecologies, in contrast to rainfed rice that is indicated among the earliest systems in India. When rice first spread north it was not entirely suited to shorter temperate summer growth seasons, and we are able to infer from high levels of apparently green-harvested spikelets that genetic adaptations to temperate conditions evolved after 2000 BC. When rice first spread south, to mainland Southeast Asia, after 2500 BC, it was grown in rainfed, dry ecologies that were less labour-demanding and less-productive. More productive and intensive irrigated rice then redeveloped in Southeast Asia around 2000 years ago, supporting growing population densities and social complexity.

The beginnings of rice and millet agriculture in prehistoric Japan

This paper reviews recent archaeobotanical evidence of the beginnings of rice and millet agriculture in prehistoric Japan, focusing on agricultural weed assemblages from early rice cultivation sites. In this study we show that the most reliable dispersal timing of rice and millet cultivation was the end of the Final Jomon period, corresponding to the Initial and Early Yayoi period of northern Kyushu. Rice and millet were introduced from China via Korea probably at the same time, as a pair. Early rice cultivation was likely practiced, not in slash-and-burn fields but in primitive paddy fields, which did not possess clearly defined paddy ridges or compartments, and were constructed in human-managed open wetlands near forests. Millets were probably cultivated on upland farmlands close to rice paddy fields. The use of berries and nuts which was the subsistence base of Jomon period continued during this time, and rice and millet agriculture gradually spread up until the Middle to Late Yayoi period.

Archaeobotanical implications of phytolith assemblages from cultivated rice systems, wild rice stands and macro-regional patterns

Rice can be cultivated in a range of arable systems, including upland rainfed, lowland rainfed or irrigated, flooded or décrue, and deep water cultivation. These agricultural regimes represent ecosystems controlled to large degree by agricultural practices, and can be shown to produce different weed flora assemblages. In order to reconstruct early rice cultivation systems it is necessary to better establish how ancient rice farming practices may be seen using archaeobotanical data. This paper focuses on using modern analogue phytolith assemblages of associated crop weeds found within cultivation regimes, as well as in wild rice stands (unplanted stands of Oryza nivara or Oryza rufipogon), as a means of interpreting archaeobotanical assemblages. Rice weeds and sediment samples have been recorded and collected from a range of arable systems and wild stands in India. The husks, leaves and culms of associated weeds were processed for phytolith reference samples, and sediment samples were processed for phytoliths in order to establish patterns identifiable to specific systems. The preliminary results of the phytolith analysis of samples from these modern fields demonstrate that phytolith assemblage statistics show correlation with variation in rice cultivation systems on the basis of differences in environmental conditions and regimes, with wetness being one major factor. Analysis of phytoliths from archaeological samples from contrasting systems in Neolithic China and India demonstrate how this method can be applied to separate archaeological regions and periods based on inferred differences in past agricultural practices, identifying wet cultivation systems in China, dry millet-dominated agriculture of north China and rainfed/dry rice in Neolithic India.

Pathways to Asian Civilizations: Tracing the Origins and Spread of Rice and Rice Cultures

AbstractModern genetics, ecology and archaeology are combined to reconstruct the domestication and diversification of rice. Early rice cultivation followed two pathways towards domestication in India and China, with selection for domestication traits in early Yangtzejaponicaand a non-domestication feedback system inferred for ‘proto-indica’. The protracted domestication process finished around 6,500–6,000 years ago in China and about two millennia later in India, when hybridization with Chinese rice took place. Subsequently farming populations grew and expanded by migration and incorporation of pre-existing populations. These expansions can be linked to hypothetical language family dispersal models, including dispersal from China southwards by the Sino-Tibetan and Austronesian groups. In South Asia much dispersal of rice took place after Indo-Aryan and Dravidian speakers adopted rice from speakers of lost languages of northern India.

The contribution of rice agriculture and livestock pastoralism to prehistoric methane levels

We review the origins and dispersal of rice in Asia based on a data base of 443 archaeobotanical reports. Evidence is considered in terms of quality, and especially whether there are data indicating the mode of cultivation, in flooded (‘paddy’ or ‘wet’) or non-flooded (‘dry’) fields. At present it appears that early rice cultivation in the Yangtze region and southern China was based on wet, paddy-field systems from early on, before 4000 bc, whereas early rice in northern India and Thailand was predominantly dry rice at 2000 bc, with a transition to flooded rice documented for India at c. 1000 bc. On the basis of these data we have developed a GIS spatial model of the spread of rice and the growth of land area under paddy rice. This is then compared with a review of the spread of ungulate livestock (cattle, water buffalo, sheep, goat) throughout the Old World. After the initial dispersal through Europe and around the Mediterranean (7000–4000 bc), the major period of livestock expansion is after 3000 bc, into the Sub-Saharan savannas, through monsoonal India and into central China. Further expansion, to southern Africa and Southeast Asia dates mostly after 1000 bc. Based on these two data sets we provide a quantitative model of the land area under irrigated rice, and its likely methane output, through the mid to late Holocene, for comparison to a more preliminary estimate of the expansion of methane-producing livestock. Both data sets are congruent with an anthropogenic source of later Holocene methane after 3000 bc, although it may be that increase in methane input from livestock was most significant in the 3000–1000 bc period, whereas rice paddies become an increasingly significant source especially after 2000 bc.

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 Early Rice Project: From Domestication to Global Warming

The Early Rice Project, at the UCL Institute of Archaeology, is clarifying the origins of Asian rice agriculture. In the Lower Yangtze region of China, we have found the tipping point when domesticated forms first outnumber wild types c.4600 BC. Investigations of assorted weed flora are also revealing how the cultivation of rice changed over time, with early cultivation in small, irregular, dug-out paddy fields in the Lower Yangtze from c.4000 BC, providing a means for the careful control of water conditions. We also work on early rice cultivation in Thailand and India. By better characterising how rice was cultivated across its entire range, we aim to model the ancient output of atmospheric methane from wet rice fields, as this was a potential contributor to the long story of human-caused global warming.

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.