ITS1 SEQUENCES OF NUCLEAR RIBOSOMAL DNA IN WILD RICES AND CULTIVATED RICES OF CHINA AND THEIR PHYLOGENETIC IMPLICATIONS

The first internal transcribed spacer(ITS1) of nuclear ribosomal DNA of three wild rice species and two subspecies of cultivated rice, which are distributed in China, was amplified using PCR technique and sequenced with automated fluorescent sequencing. The sequences of ITS1 ranged from 193 bp to 218 bp in size and G/C content varied from 69.3% to 72.7%. In pairwise comparisons among the five taxa, sequence site divergence ranged from 1.5% to 10.6%. Phylogenetic analysis of ITS1 sequences using Wagner parsimony generated a single well resolved tree, which revealed that Oryza rufipogon was much more closely related to cultivated rice species than to the other two wild species. Oryza granulata was less closely related to either cultivated rice species or the other two wild species, and might be a unique and isolated taxon in the genus Oryza. The phylogenetic relationships of the three wild rice species and two cultivated rice subspecies inferred from ITS1 sequences is highly concordant with those based on the molecular evidence from isozyme, chloroplast DNA (cpDNA), mitochondrial DNA(mtDNA) and nuclear DNA (nDNA) of the genus Oryza .

Comparison of Neutral Detergent Fiber,Acid Detergent Fiber and Acid Detergent Lignin Contents of Dongxiang Wild Rice and Cultivated Rice

[Objective] To study the chemic component of rice cell wall among different varieties and at different rice growth stages.[Method] The contents of neutral detergent fiber（NDF）,acid detergent fiber（ADF） and acid detergent lignin （ADL） of rice were analyzed by Van Soest Method.[Result] The contents of NDF,ADF and ADL varied from 55.63% to 71.70%,31.98% to 49.61% and 2.68% to 5.71% respectively,the highest content was gained in Dongxiang wide rice at dough stage,while the lowest content was obtained in rice heading stage of Xieqingzao B.In the same growth stage,the contents of NDF（except heading stage） and ADF were significantly（P0.05 or 0.01） difference among three varieties of rice,the highest content was Dongxiang wide rice,followed by Xiushui 110,and the lowest was Xieqingzao B.In the same variety rice,the content of NDF and ADF were significantly （P0.05 or 0.01） difference among three rice growth stages,the lowest contents was rice heading stage,followed by rice milk ripe stage,the highest was rice dough stage.[Conclusion] the NDF,ADF and other contents of indica rice were lower than that of ordinary wild rice and japonica rice,therefore,it owned a certain value in use of straw feed.If the indica rice could be harvest as earlier as possible,the rice straw together with silage fermentation and enzymatic hydrolysis could provide the effective diet for livestock.

Effects of Soaking Cultivated Rice Seeds with Fulvic Acid on Physiological and Ecological Properties of Weedy Rice

[Objective] This study aimed to investigate the effects of soaking cultivated rice seeds with fulvic acid （FA） on physiological and ecological properties of weedy rice in the direct seeding cultivated rice field. [Method] Weedy rice JS-Y1 and culti-vated rice Nanjing 44 were used as experimental materials for field plot trials to an-alyze the effects of soaking cultivated rice seeds with 0 （water as control）, 4, 6, 8 g/L FA on til ering dynamics, plant height, chlorophyl content, photosynthetic perfor-mance, gas exchange parameters and yield components of weedy rice at different growth stages. [Result] Among the 4 plants/m2 weedy rice plots, with the increase of FA concentration, til er number, plant height, chlorophyl content, net photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） of weedy rice were reduced. Under the 4-6 g/L FA concentration, til er numbers of weedy rice at differ-ent growth stages were reduced by 13.84%-35.71% compared with control at the same density and the most significant reduction was on the 22nd d after weedy rice germination; chlorophyl contents of weedy rice at the jointing stage were significant-ly reduced by 7.90%-8.88%. Furthermore, in the plots with 4 g/L FA, weedy rice plant heights at the heading stage and grain fil ing stage were significantly reduced by 6.37%-9.10%; Pn, Gs and Tr of weedy rice at the jointing stage and grain fil ing stage were significantly reduced by 10.19%-16.05%, 12.57%-23.33% and 10.28%-19.76%, respectively; 1 000-grain weight, effective panicle number per plant and panicles weight per plant of weedy rice at the maturity stage were significantly re-duced by 3.19%, 21.21% and 27.27%, correspondingly. [Conclusion] In 4 plants/m2 weedy rice plots, because soaking cultivated rice seeds with 4 g/L FA could regu-late the growth and development of cultivated rice, the soaking with FA could change the ecological relationship between cultivated rice and weedy rice, affect weedy rice physiological and ecological properties and al eviate the competitive inhi-bition of weedy rice on cultivated rice.

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/

Comparison of Genetic Diversity Between Local Cultivated Aromatic and Non-aromatic Rice in Yunnan Province

[ Objective] The genetic diversity of the local cultivated aromatic rice and non-aromatic rice in Yunnan Province were compared to provide further genetic resources for breeding practice. [Method] Genetic diversity of 10 aromatic rice and 45 non-aromatic rice were analyzed by 64 SSR primers covered on 12 rice chromosomes. [ Result] Per locus 5.44 and 7.98 alleles in average were detected, ranging from 2 to 12 and from 2 to 17 in aromatic and non-aromatic rice, respectively. Average genetic multiplicity index（Hs） was 0.46 and 0.67 respectively. The average polymorphism information content （PIC） was 0.43 and 0.58 in aromatic and non-aromatic rice respectively. [ Conclusion] The results indicated that genetic diversity was higher in non-aromatic rice than in aromatic rice.

Rice Cultivation under Film Mulching Can Improve Soil Environment and Be Beneficial for Rice Production in China

Rice cultivation under film mulching is an integrated management technology that can conserve water, increase soil temperature, improve yield, and enhance water and nitrogen use efficiencies. Despite these advantages, the system does have its drawbacks, such as soil organic matter reduction and microplastic pollution, which impede the widespread adoption of film mulching cultivation in China. Nonetheless, the advent of degradable film, controlled-release fertilizer, organic fertilizer, and film mulching machinery is promoting the development of rice film mulching cultivation. This review outlines the impact of rice cultivation under film mulching on soil moisture, soil temperature, soil fertility, greenhouse gas emissions, weed control, and disease and pest management. It also elucidates the mechanism of changes in rice growth, yield and quality, water use efficiency, and nitrogen use efficiency. This paper incorporates a review of published research articles and discusses some uncertainties and shortcomings associated with rice cultivation under film mulching. Consequently, prospective research directions for the technology of rice film mulching cultivation are outlined, and recommendations for future research into rice cultivation under film mulching are proposed.

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.

The Historical Status of Guizhou Province on Glutinous Rice Cultivation Sphere of China

Guizhou Province is part of the glutinous rice cultivation sphere in our country.Its rice production and germplasm resources play an important role.The southeast region is the centre of the Guizhou glutinous rice cultivation and characterized by waxy wo,which is treasure of the original farming culture of southeast Guizhou region and an important symbol for ethnic cultural identity of the region.

Analysis on Input-Output in Rice Cultivation Based on Cobb-Douglas Production Function

[Objective] To analyze the input and output in rice cultivation based on CD function. [Method] Based on the input factors, Cobb-Douglas production （CD） function was used to do the quantitative analysis on the input-output in rice production with rice growers as the objective. [Result] Considering the substitution effect of labor in- put and capital input, under the same technical conditions, the effect of increasing labor input on the rice production in per 667 m2 was negative, based on which 2 pieces of policy suggestions were put forward to promote the transfer of surplus la- bor force of rice growers and ensure the capital supply for rice production. [Conclusion] This study laid the foundation for the realization of reasonable allocation of rice production resources.

Effects of Land Management Practices on Labile Organic Carbon Fractions in Rice Cultivation

A research trial with four land management practices, i.e., traditional tillage-fallow (TTF), traditional tillage-wheat (TTW), conservation tillage-fallow (CTF) and conservation tillage-wheat (CTW), was sampled in the 15th year after its establishment to assess the effects of different management practices on labile organic carbon fractions (LOCFs), such as easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC) and microbial biomass carbon (MBC) in a typical paddy soil, Chongqing, Southwest China. The results indicated that LOCFs were significantly influenced by the combination of no-tillage, ridge culture and crop rotation. And, different combination patterns showed different effectiveness on soil LOCFs. The effects of no-tillage, ridge culture and wheat cultivation on EOC, DOC, POC and MBC mainly happened at 0-10cm. At this depth, soil under CTW had higher EOC, DOC, POC and MBC contents, compared to TTF, TTW and CTF, respectively. Moreover, the contents of LOCFs for different practices generally decreased when the soil depth increased. Our findings suggest that the paddy soil in Southwest China could be managed to concentrate greater quantities of EOC, DOC, POC and MBC.

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 Seedling Cutivation with Mat-fiber Mulch on Quality and Quantity of Early-season Rice

[Objective] The aim was to explore effects of tray mat of fiber mulch on quality and yield of early rice-season rice transplanted by machine. [Method] Seedling quality, the rate of leaked rice, density of mechanical transplanting rice, mature rate and yield covered with fiber mulch were compared with groups not covered with mulch. Furthermore, different indices of cultivated rice with and without fiber mulch were analyzed and compared. [Result] The rice yield in the group with fiber mulch improved by 11.9% and rice quality enhanced as wel . What＇s more, rice plants were much easier to be col ected, and the rate of leaked rice lowered by machine. [Conclusion] The research provides theoretical references for seedling transplanting and cultivation of early-season rice by machine with tray mats.

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.

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.

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.