What happened during domestication of wild to cultivated rice

Domestication of crops is one of the greatest inventions of the human race and has played a vital role in the progress of human civilization.Understanding the genetic mechanisms of crop domestication could shed light on its history and would advance crop breeding.Cultivated rice species,which were domesticated from wild rice species,are important food crops worldwide.Morphological traits,physiological characteristics,and ecological adaptability of cultivated rice are very different from those characters of wild rice.In this review,we summarize current knowledge of the genetic mechanisms underlying these differences between wild and cultivated rice and discuss the application of wild rice species in modern breeding.

Genetic Diversity Based on Allozyme Alleles of Chinese Cultivated Rice

Genetic diversity was analyzed with 6 632 core rice cultivars selected from 60 282 Chinese rice accessions on the basis of 12 allozyme loci, Pgil, Pgi2, Amp1, Amp2, Amp3, Amp4, Sdhl, Adhl, Estl, Est2, Est5 and Est9, by starch gel electrophoresis. Among the materials examined, 52 alleles at 12 polymorphic loci were identified, which occupied 96.3% of 54 alleles found in cultivated germplasm of O. sativa L. The number of alleles per locus ranged from 2 to 7 with an average of 4.33. The gene diversity （He） each locus varied considerably from 0.017 for Amp4 to 0.583 for Est2 with an average gene diversity （Ht） 0.271, mid Shannon-Wiener index from 0.055 to 0.946 with an average of 0.468. The degree of polymorphism （DP） was in a range from 0.9 to 46.9% with an average of 21.4%. It was found that the genetic diversity in japonica （Keng） subspecies was lower in terms of allele＇s number, Ht and S-W index, being 91.8, 66.2 and 75.7% of indica （Hsien） one, respectively. Significant genetic differentiation between indica and japonica rice has been appeared in the loci Pgil, Amp2, Pgi2, and Est2, with higher average coefficient of genetic differentiation （Gst） 0.635, 0.626, 0.322 and 0.282, respectively. Except less allele number per locus （3.33） for modern cultivars, being 76.9% of landraces, the Ht and S-W index showed in similar between the modem cultivars and the landraces detected. In terms of allozyme, the rice cultivars in the Southwest Plateau and Central China have richer genetic diversity. The present study reveals again that Chinese cultivated rice germplasm has rich genetic diversity, showed by the allozyme allele variation.

Study on the ancient cultivated rice in China

Sixty-eight ancient cultivated rice grains of 10 ruins of 2000-15000 BP in theChangjiang River valley were studied by analyzing grain shape, using discri-minat formulas of hi-peaked tubercle(BPT) with the G (x) = 44. 4788 -0. 4308X- 0. 4263 X+ 0. 078 X, where Xis hi-peaked distance( BPD), Xis peaked angle (PA), and Xis ratio of hi-peaked distance/col depth (BPD/

Rice vs.Wheat:How Rice Farming Shaped Informal Finance in China

China’s financial system is characterized by the coexistence of both formal and informal finance,and informal finance appears to be more prevalent in the south of the country compared to the north.In this paper,we use the historical demarcation of rice-farming regions and the percentage area of rice sown to ascertain the regional distribution of rice farming in the south and wheat farming in the north in order to analyze the role of rice farming in the evolution of different types of financial institutions in China.We find that rice cultivation has a positive effect on informal financial development,though its impact on formal finance is insignificant.Unlike wheat farming,rice cultivation requires farmers to collaborate during busy farming seasons and necessitates the construction of irrigation systems.Such collaboration helped enhance an acquaintance society,in which both parties to transactions enforced the rules and contract terms of their own initiative,paving the way for informal finance.This paper not only demonstrates the cultural roots of the regional financial disparities in China but also expands the research on the ways in which farming practices from the past have shaped the development of China’s present financial markets.

Delineating the rice crop activities in Northeast China through regional parametric synthesis using satellite remote sensing time-series data from 2000 to 2015

Accurate rice area extraction and yield simulations are important for understanding how national agricultural policies and environmental issues affect regional spatial changes in rice farming. In this study, an improved regional parametric syntheses approach, that is, the rice zoning adaptability criteria and dynamic harvest index(RZAC-DHI), was established, which can effectively simulate the rice cultivation area and yield at the municipal level. The RZAC was used to extract the rice area using Moderate Resolution Imaging Spectroradiometer time-series data and phenological information. The DHI was calculated independently, and then yield was obtained based on the DHI and net primary productivity(NPP). Based on the above results, we analyzed the spatial–temporal patterns of the rice cultivation area and yield in Northeast China(NEC) during 2000–2015. The results revealed that the methods established in this study can effectively support the yearly mapping of the rice area and yield in NEC, the average precisions of which exceed 90 and 80%, respectively. The rice planting areas are mainly located on the Sanjiang, Songnen and Liaohe plains, China, which are distributed along the Songhua and Liaohe rivers. The rice cultivation area and yield in this region increased significantly from 2000 to 2015, with increases of nearly 58 and 90%, respectively. The rice crop area and yield increased the fastest in Heilongjiang Province, China, whereas small changes occurred in Jilin and Liaoning provinces, China. Their gravity centers exhibited evident northward and eastward shifts, with offset distances of 107 and 358 km, respectively. Moreover, Heilongjiang Province has gradually become the new main rice production region. The methodologies used in this study provide a valuable reference for other related studies, and the spatial-temporal variation characteristics of the rice activities have raised new attention as to how these shifts affect national food security and resource allocation.

The Origin of Flooded Rice Cultivation

Rice cultivation has long been considered to have originated from seeding of annual types of wild rice somewhere in subtropics, tropics or in the Yangtze River basin. That idea, however, contains a fatally weak point, when we consider the tremendous difficulty for primitive human to seed any cereal crop in the warm and humid climate, where weed thrives all year round, instead of the accepted theory, we have to see a reality that vegetative propagation of edible plants is a dominant form of agriculture in such regions. The possibility is discussed that Job＇s tears and rice, two cereal crops unique to the region, might have been developed via vegetative propagation to obtain materials for medicine or herb tea in backyard gardens prior to cereal production. This idea is supported by the fact that rice in temperate regions is still perennial in its growth habit and that such backyard gardens with transplanted taro can still be seen from Yunnan Province of China to Laos. Thanks to detailed survey of wild rice throughout China for 1970-1980, it is now confirmed that a set of clones of wild rice exist in shallow swamps in Jiangxi Province, an area with severe winter cold. In early summer ancient farmers may have divided the sprouting buds and spread them by transplanting into flooded shallow marsh. Such way of propagation might have faster improved less productive rice through a better genetic potential for response to human interference than quick fixation in seed propagation, because vegetative parts are heterogeneous. Obviously, such a primitive manner of rice cultivation did include the essential parts of rice farming, i.e., nursery bed, transplanting in flooded field of shallow marsh like. Transfer from the primitive nursery to true nursery by seed may have later allowed rice cultivation to be extended to northern regions. In thus devised flooded cultivation there were a series of unique advantages, i.e.; continuous cropping of rice in a same plot, no soil erosion, slow decline of soil fertility, availability of minerals, and resulting in high yield per unit area, which have collectively attained the highly productive cereal cultivation in the warm and humid region. Rice cultivation in marsh is also favorable to raise fish culture, both of which constituted a nutritionally balanced base. Development of irrigation technology to construct flooded farms gave strong bases for stable rice-cultivating society, which in the end formulated the rise of ancient kingdoms of Yue and Wu in China in BC 6th -5th centuries. They were direct descendents of those people who had developed the unique rice cultivation from the era of Hemudu culture, which is dated back to 5 000 BC. Their movement to the south is considered to have established rice-cultivating communities in South China and Southeast Asia, while to the north it transferred the rice-based technology to ancient Korea and Japan and had established there a base for a civilized society.

Effects of light-emitting diodes on tissue culture plantlets and seedlings of rice (Oryza sativa L.)

Light-emitting diodes(L EDs)are a new light source with low energy consumption and high photoelectric conversion efficiency,and they can satisfy the energy-saving needs of plant culture systems.However,the effects of LED light sources on rice tissue culture and rice seedling cultivation are poorly understood.This study aimed to evaluate the effects of LEDs on the growth of tissue culture plantlets and seedlings of the rice(Oryza sativa L.)cultivar Nipponbare.The best light source for rice tissue culture was different from that for rice seedling cultivation.Blue(B)LED light was the most appropriate light for rice tissue culture.Under a B LED light,the time required for callus proliferation,differentiation and regeneration was the shortest,and the frequency of plantlet ititin,dfferetiation and regeneration was the highest.Ablue:red(B:R)=1:1LED light facilitated the growth of rice seedlings and produced the highest chlorophyll and carotenoid contents and photosynthetic rates in the rice seedlings.Abundant photosynthetic products were more effectively generated in the rice seedlings under the B:R=1:1 LED and R LED lights than under the B LED light.B LED light is the most appropriate light for rice tissue culture plantlets and can be used as an alternative light source for rice tissue culture,and B:R=1:1 LED light facilitated the cultivation of robust rice seedlings and can be used as the primary light source for rice factory seedling cultivation.

Effects of Biochar Particle Size on Methane Emissions from Rice Cultivation

Biochar amendment is generally recognized as an effective mitigation option of methane(CH_(4))emissions from rice cultivation.Although its mitigation mechanisms are not well understood,the potential relevance of surface area and porosity of biochar has been discussed.This study aimed to evaluate the application of different biochar particle sizes on CH_(4) production,oxidation,and emissions from rice cultivation in a clay loam soil,based on the assumption that porosity and surface area of biochar are directly related to its mitigation effects.Rice was grown under greenhouse conditions for two growing seasons,either with 0.5–2 mm(small,SB)or with 2–4 mm(large,LB)biochar.The results show that both sizes of biochar increased soil pH and redox potential(Eh)during rice growth.Soil dissolved organic carbon(DOC),nitrate(NO^(−)_(3)),and sulfate(SO^(2−)_(4))also increased under both biochar amendments,but size effects were not observed.SB and LB suppressed the abundance of CH_(4) producers(methanogens)but stimulated the abundance of CH_(4) consumers(methanotrophs).The increase of soil Eh and electron acceptors(NO^(−)_(3)and SO^(2−)_(4))indicated the increase in soil oxidation capacity is a barrier to CH_(4) production by methanogens in both biochar treatments.Laboratory incubation experiments showed that CH_(4) production activity was significantly(p≤0.05)reduced by 18.5%using SB and by 11.3%using LB compared to the control.In contrast,the stimulation of methanotrophs promoted greater CH_(4) oxidation activity by 15.0%in SB and 18.7%in LB compared to the control.It shows that CH_(4) production was reduced more by larger surface area biochar(SB),while a greater increase in CH_(4) oxidation was found using larger pore volume biochar(LB).The effects on CH_(4) production were more pronounced than those on CH_(4) oxidation,resulting in a greater reduction of cumulative CH_(4) emissions by SB than LB(by 26.6%and 19.9%compared to control,respectively).

Current Situation,Problems and Optimization Countermeasures of Rice and Shrimp Cultivation Industry in Hubei Province

In recent years,the scale of rice and shrimp cultivation in Hubei Province is expanding year by year,and cultivation model is innovating continuously,while consumption market is enlarging constantly.It realizes"dual use of one land,win-win of grain and fishery,stable grain production,and efficiency increase",and effectively solves the problems that"benefit of grain planting is low,and it is difficult to increase farmers'income".But there are still many problems at present,such as degeneration of crayfish germplasm,increase of disease incidence,centralized entering in the market affecting breeding efficiency,the benefits of rice not brought into full play,large number of business entities,lack of leading enterprises and sufficient supporting.To realize sustainable development of rice and shrimp cultivation industry,Hubei Province should adhere to the problem orientation,do a good job in supporting and capital guidance,increase effective supply,promote scale operation,cultivate leading enterprises,strengthen production management,and improve product quality.

Effects of Irrigation with Well Water on Chemical Characteristics of a Weakly Alkaline Soil Used as Rice Field

This paper discussed the effects of irrigation with well water on the salinity and pH of a weakly alkaline paddy soil in Fujin of Heilongjiang Province in the north-eastern part of China.It has been found that after seven years the accumulation of total soluble salts did not occur and that the pH of 0～15 cm layer fell down from 7.92～8.30 to 6.76～7.45,and that the content of anion HCO - 3 and its proportion in the total soluble anions have fallen down.Conversion from paddy soil to upland restored the pH of soil,exchangeable sodium,ESR(exchangeable sodium ratio) to their original levels of upland fields respectively.

Sustainable Development of Wannian Rice Cultivation Culture System

Based on the research on the relevant background and significance of the sustainable development of agricultural cultural heritage,taking Wannian rice cultivation culture system as an example and its natural environment,traditional agricultural production activities,unique cultural patterns,socio-economic development and protection,and protection and development approach as the basis for evaluation,an evaluation index system for the sustainable development of Wannian rice cultivation culture system was constructed.Each index was quantified and standardized,and their weight was determined through the analytic hierarchy process to obtain the comprehensive evaluation value of the sustainable development of Wannian rice cultivation culture system.The evaluation value was analyzed to propose the main issues in the sustainable development of Wannian rice cultivation culture.

Assessment of the Contribution of Flooded Rice Cultivation Systems to Methane Emissions in the Lower OuéméValley, in Benin Republic

Flooded rice cultivation fields appear to be the major source of methane emission. In Benin Republic, flooded rice is cultivated in the Niger River and Ouémé River Basins. The present study aims to assess the contribution of flooded rice cultivation systems to methane emissions in the lower Ouémé Valley. Methane emission calculation was based on Activity Data which is the flooded rice harvested surface area from 2008 to 2017. The Tier 2 methodology of the IPCC 2006 Guidelines’ and the complements of the “Refinement 2019” have been used to elaborate the specific emission factors for the lower valley of Ouémé and to estimate the emission of methane in this zone. Semi-structured interviews were conducted with producers in order to elaborate on their perceptions of gas emissions in the flooded rice fields. The EX-ACT tool was used to estimate the carbon footprint of the intensive rice cultivation system “SRI” and the conventional rice cultivation system “SRC”. It is shown that producers have a strong perception of gas emissions in rice fields but are totally unaware of the nature of the gas. Methane emitted in the lower valley of the Ouémé is around 528 tons/year between 2008 and 2017 while the carbon footprint resulting from the results of EX-ACT for the adoption of the SRI rises to the level of sequestration of approximately 0.4 tCH4/ha/year. The intensive rice cultivation system has been identified as the production system that minimizes methane emissions and maximizes rice production.

Assessment of the Physicochemical Quality of Irrigation Water and Soil for Sustainable Irrigated Rice Cultivation:Case of Irrigated Perimeter of M’Bahiakro(Central-East of Cote d’Ivoire)

This study aims to assess the physico-chemical quality of irrigation water and soil in the irrigated area of M’Bahiakro. Seasonal campaigns to measure in situ the physical parameters (pH, temperature, salinity, electrical conductivity and total dissolved solids) of the N’Zi River were carried out, followed by sampling (water and soil) for chemical analyses. The physico-chemical quality of irrigation water was assessed on the basis of four (4) parameters, namely Dry Residue (SR), Osmotic Pressure (π), Kelly Coefficient (KCR), Sodium Absorption Rate (SAR) and Wilcox Diagram. In terms of soil quality, the parameters (pH, N, P, P, K, MO, CEC and ESP) were determined. Overall, the results show a good physical-chemical quality of the irrigation water and soil. Indeed, the irrigation waters studied show good physico-chemistry and low to medium salinity depending on the seasons of the year. As for the soils, they have a clayey-silt texture, a slightly acidic pH, favourable to rice cultivation and a good organic matter content, which best maintains an active microbial life. In addition, the major elements (nitrogen, phosphorus and potassium) present in irrigation water and soils could be enough to optimize the yield of rice cultivation. These results then lead to the conclusion that the irrigation water from the N’Zi River and the soils of the irrigated perimeter of M’Bahiakro are naturally suitable for agricultural use, particularly for rice cultivation. As a result, an additional supply of fertilizer (NPK) would not necessarily be necessary during the exploitation phase of the rice area.

Origin and cultivation history of rice in China

cies of cultivated rice in ancient China is possibly more northward than in the modern times. The earliest rice grains unearthed from the Neolithic sites existed along the lower and middle reaches of the Yangtze River. The later ones were found in Yunnan Province, South China and along the Yellow River reaches. Primitive rice cropping in the Taihu Lake region which is on the lower reach of the Yangtze River has already a 6,000-7,000 years history and the primitive tribes growing rice there are ancestors of the Yue Nationality since the beginning of the history, hence the Yue Nationality is the most important one for rice cropping in China. During the periods of Spring-Autumn and Warring States to Qin and Han Dynasties (from 722 B.C. to A.D.220 ), Yue people disseminated rice to Japan, Korea and other Southeast Asian countries by sea. In the period of over 3,000 years since the recorded history,the rice development in China has experienced changes from north to south and from south to north. As Chinese c

Rice cultivation on floating-beds in different natural waters

Following the success in rice cultivation onfloating-beds in natural water in 1990,the eco-logical adaptability of growing rice on floating-beds was studied during the period of 1991-1993.Experiments were conducted in five dif-ferent types of natural waters in ZhejiangProvince from 28°35′ to 30°58′N and from 119°05′ to 121°11′E.The results indicated that:1)Yield of double-cropping early ricegrowing on floating-beds was lower than one

Studies on high-yielding cultivation of rice in Guangdong by diagnosis and control of chlorophyll content and LAI

During the 1970’s and 1980’s studies on the rela-tion between LAI and yield had been carried out inGAAS.The main results were as follows:(1)Usingthe accumulated LAI value at three stages,i.e.panicle initiation(PI),heading(H)and 20 d afterheading(H),to analyze the relation between LAIand yield was more accurrate than only using theLAI value at H stage(see table);(2)Reaching cer-

Use of Multi-Method Approach for a Gravity Irrigation Network Diagnosis: Case of Karfiguela Paddy Field in Burkina Faso

Burkina Faso is an agricultural and landlocked country whose agriculture is dependent on climatic hazards. Irrigated agriculture therefore appears as an alternative to secure, intensify and sustainably increase agricultural production. However, irrigation systems in Burkina Faso suffer from numerous technical, organizational, land and structural problems, which strongly undermine their performance. This is the case of the irrigated perimeter of Karfiguéla which since its development in 1977, has experienced insufficient water. This research has contributed to the reflection on the performance and operation of gravity irrigation networks on the irrigated perimeter in Burkina Faso and the contribution of satellite images in the mapping of irrigated perimeters. Then, an approach based on a mapping of hydraulic networks and on four main diagnostic methods were used: 1) mapping of hydraulic networks, 2) a detailed visual inspection of hydraulic infrastructure, 3) estimation of canals’ hydraulic efficiency, 4) surveys of the various actors involved in the management of the perimeter. These methods lead to the same results concerning the state of degradation and the functioning of irrigation networks in wet seasons. In terms of results, Karfiguéla perimeter has a net area of 360 ha and is supplied by a network made up of a supply canal, a primary canal, four (4) secondary canals, 37 tertiary ones, and quaternary ones for plots of water supply, all in ordinary concrete except the quaternary which are in rammed soil. The efficiency of the canals in the rainy season, greater than 100%, shows that the irrigation network during this period functions as a drainage network while the real drainage network is disorderly and non-functional. The damage to the irrigation network, siltation, grassing, erosion, overturning, large cracks and many others are all the more severe as we advance toward the Quaternary. The Strickler roughness coefficient values of the order of 68 for the feeder, 47 for the primary, between 32 and 52 for the secondaries and 31 for the tertiaries also reflect a high degradation of the channels. Upkeep and maintenance are rare and generally poorly executed. Improving the performance of irrigation on the perimeter requires a complete rehabilitation of the hydraulic network, the reinforcement of the management and maintenance capacity of the operators’ works and the search for a water resource complementary to the Comoé River to support irrigation, for example, the exploitation of the alluvial aquifer which unfolds under the perimeter and is easily accessible through rudimentary wells and sumps. All this is essential to ensure the sustainability of the rice-growing activity, which has a concentration of nearly 1200 farmers.

Soil Fertility Is a Productive Capital Asset

In recent years, the understanding of human health has progressed considerably, through the study and understanding of the symbiotic role played by the myriad microorganisms that populate the gut and do the digesting, and populate the skin and keep it healthy, and even populate the lining of the lungs and do the same. In plant life, it is the microorganisms in the soil—which “are” the soil’s fertility—which fulfil a similar symbiotic role in a healthy plant’s life, but as yet this is a subject most visible by its absence from all scientific discussion of good farming practice. The science underlying this understanding is summarised in this paper. Understanding this and nurturing the fertility of impoverished soil by “seeding it” with the appropriate mix of microorganisms is transformational for plant health and productivity. Significant results are indicated from early trial examples of doing this in rice, oil palm and tobacco cultivation in Malaysia.

Differentiation of Indica-Japonica rice revealed by insertion/deletion(InDel)fragments obtained from the comparative genomic study of DNA sequences between 93-11(Indica)and Nipponbare (Japonica)

DNA polymorphisms from nucleotide insertion/deletions(InDels)in genomic sequences are the basis for developing InDel molecular markers.To validate the InDel primer pairs on the basis of the comparative genomic study on DNA sequences between an Indica rice 93-11 and a Japonica rice Nipponbare for identifying Indica and Japonica rice varieties and studying wild Oryza species,we studied 49 Indica,43 Japonica,and 24 wild rice accessions collected from ten Asian countries using 45 InDel primer pairs.Results indicated that of the 45 InDel primer pairs,41 can accurately identify Indica and Japonica rice varieties with a reliability of over 80%.The scatter plotting data of the principal compo-nent analysis(PCA)indicated that:(i)the InDel primer pairs can easily distinguish Indica from Japonica rice varieties,in addition to revealing their genetic differentiation;(ii)the AA-genome wild rice species showed a relatively close genetic relationship with the Indica rice varieties;and(iii)the non-AA genome wild rice species did not show evident differentiation into the Indica and Japonica types.It is con-cluded from the study that most of the InDel primer pairs obtained from DNA sequences of 93-11 and Nipponbare can be used for identifying Indica and Japonica rice varieties,and for studying genetic relationships of wild rice species,particularly in terms of the Indica-Japonica differentiation.

Suitability mapping for rice cultivation in Benue State,Nigeria using satellite data Fanan Ujoh

With rising population,decline in soil productivity and land-based conflicts,the per-capita land availability for cultivation is rapidly decreasing within Benue State,a largely agrarian and small-holder setting.This study attempts a local-level support for the actualisation of Sustainable Development Goal Number 2(“end hunger,achieve food security and improved nutrition,and promote sustainable agriculture”)by 2030.Using Multi-Criteria Decision Making(MCDM)method,remote sensing data from Climate Research Unit(CRU)and in-situ data from Nigeria Meteorological Agency(NIMET)were analyzed by GIS techniques to map the suitability of rice cultivation in the study area,with the integration of Normalized Difference Vegetation Index(NDVI),land cover,slope,temperature,precipitation and soil parameters(cation exchange capacity,pH,bulk density,organic carbon).We apply the various statistical parameters that include mean spatial NDVI;correlation coefficient,standard deviation and Root Mean Square(RMS)between CRU and NIMET data.Spatial regression trend analysis is conducted between CRU precipitation and NDVI and between CRU temperature and NDVI from 1985 to 2015.The results reveal that NDVI in highly suitable rice planting regions is higher than marginally suitable regions except in the months of October and November,which shows that the highly suitable regions will yield better than the marginally suitable regions during the dry season.Additionally,NDVI is seasonally bimodal in response to precipitation,meaning that vegetation vigor is more dependent on precipitation than temperature.Finally,the correlation coefficient,standard deviation and RMS between CRU and NIMET precipitation data shows 0.42,108,and 110,respectively,while these three factors between CRU and NIMET temperature data shows 0.88,1.60,and 0.86,respectively.In conclusion,the MCDM approach reveals that upland is more suitable for rice cultivation in Benue State when comparing with the area provided by the Global Land Cover and National Mappings Organization(GLCNMO)data.