Improved rice varieties(IRVs)play a significant role in establishing food security and improving livelihood in the Global South since its introduction in the 1960s.However,the adoption of new IRVs has remained relativ...Improved rice varieties(IRVs)play a significant role in establishing food security and improving livelihood in the Global South since its introduction in the 1960s.However,the adoption of new IRVs has remained relatively low.This low adoption poses a challenge to rice-producing and consuming countries as they are increasingly threatened by production shortages,malnutrition,and poor rice quality.Many empirical studies have attempted to identify the determinants influencing the adoption of IRVs by distinguishing the characteristics between adopters and non-adopters.This review showed a consensus on the important determinants influencing the adoption of IRVs in the Global South.Findings synthesized from 99 studies suggested that variables(farm size,education,information access and farm location)examined extensively are not necessarily the most important determinants of adoption when undertaking a weighted analysis.Terrain,source of seed and technology-related attributes(perceived yield,maturity,ease of use,marketability and technical efficiency)are more important determinants of adoption,with determinants changing according to adoption type(probability or intensity of adoption),variety type and region.The recommendations for future adoption studies include:incorporating more technology-specific variables,increasing research for overlooked regions and variety types,shifting away from predominant static analysis by capturing the dynamics of the adoption process,and considering the potential biases in analyses.This review will facilitate the development of targeted interventions and policies that promote IRV adoption in the Global South.展开更多
In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading ri...In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.展开更多
The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germinatio...The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germination rate, shooting index, vigor index, seedling and shoot lengths, and fresh weights. The results showed that as Cd concentration grew, seed germination and seedling growth kept increasingly inhibited; germination index, vigor index, root length, shoot length and fresh weights went down; inhibition effects on seed germination and seedling growth were conventional rice〉two-line hybrid rice〉three-line hybrid ,rice. Shanyou 9588, Tianyou 998, Chuanxiang 8, and Y Liangyou 1 performed ~rongly in Cd tolerance; C Liangyou 651, Nei 5 You 263, Xiangwanxian 16, Huanghuazhan, Xiangwanxian 13, and Zhunliangyou 527 performed poorly in Cd tolerance, and Cd tolerance of rest treatments were moderate.展开更多
The nationally registered rice varieties during 2006-2015 were analyzed and there were 49.4 varieties on average annually registered in the last decade. In terms of the structure of varieties, there was a decreasing t...The nationally registered rice varieties during 2006-2015 were analyzed and there were 49.4 varieties on average annually registered in the last decade. In terms of the structure of varieties, there was a decreasing trend for the proportion of three-line hybrid rice varieties but a rapid increase for that of two-line hybrid rice varieties. The percentage of rice varieties developed by scientific research institu- tions was decreasing but that developed by seed companies kept a rapid increase, indicating the commercial breeding conducted by seed companies has become a principal model in rice breeding. With regard to grain quality of varieties, the con- ventional rice varieties showed an increasing trend while the hybrid rice varieties had a decreasing trend in the proportion of high quality varieties, indicating hybrid rice needs improving more in grain quality in breeding programs.展开更多
The research selected 16 rice varieties(8 early and 8 late double-cropping rice) by mechanical transplanting modes as per equivalent row and wide-narrow row to explore yield and physiological traits in order to prov...The research selected 16 rice varieties(8 early and 8 late double-cropping rice) by mechanical transplanting modes as per equivalent row and wide-narrow row to explore yield and physiological traits in order to provide references for selection of rice variety suitable for mechanical transplanting. The results showed that yields of early and late rice improved by 2.90% and 2.73% by mechanical transplanting as per equivalent row and wide-narrow row respectively. Besides, leaf area index in the treatment as per wide-narrow row was higher compared with the treatment as per equivalent row, as well as average photosynthetic potential which grew by 0.92%,3.99% and 5.64% of early from tillering-peak stage to mature stage and 3.46%,7.09% and 6.79% of late rice. Furthermore, by mechanical transplanting as per wide-narrow row, SPAD value, and root activity performer higher, as well as the number of differentiated branch and glumous flowers, but degradation rate showed lower. In addition, with mechanical transplanting the same, early rice Zhuliangyou819 and late rice Fengyuanyou 299 took advantages in yield, which can be priorities for mechanical transplanting in double-cropping areas in Jiangxi Province.展开更多
The traditional rice-fish farming system is selected as a "globally important agricultural heritage system" (GIAHS) by the Food and Agriculture Organization (FAO),United Nations Development Programme (UNDP),an...The traditional rice-fish farming system is selected as a "globally important agricultural heritage system" (GIAHS) by the Food and Agriculture Organization (FAO),United Nations Development Programme (UNDP),and Global Environment Facility (GEF),etc.In Zhejiang Province of China,where the pilot site for this GIAHS farming system is located,we compared the use of traditional rice varieties in rice-fish co-culture and rice monoculture.Further,we determined how traditional rice varieties were performed in this rice-fish system.Only 19% of the farmers who practiced rice monoculture planted traditional varieties while 52% of farmers who practiced rice-fish co-culture planted traditional varieties.Traditional varieties represented 13% of the total land cultivated under rice in the rice-fish system but only 2% in the rice monoculture system.In the rice-fish system,yield was lower for traditional rice varieties than hybrid varieties but application of fertilizers and pesticides was also lower.In a field experiment in the rice-fish system without pesticides,rice planthopper numbers and sheath blight incidence were lower from three traditional varieties than one hybrid variety;yields were 8 to 32% lower from the traditional varieties than the hybrid.Our results showed that traditional rice varieties can be preserved through conserving GIAHS rice-fish co-culture.Our study also indicated that traditional rice varieties can survive in the rice-fish system because these varieties are helpful to the whole system and beneficial to the farmers.展开更多
The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside th...The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa (aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica). Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly (r=0.87, P≤0.05) with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 (aus), Shenliangyou 1 (hybrid aus) and Cliangyou 4418 (hybrid indica) were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.展开更多
The use of improved high yielding crop varieties is an important avenue for reducing hunger and food insecurity in developing countries. Using cross-sectional data obtained from a survey conducted during 2013 crop sea...The use of improved high yielding crop varieties is an important avenue for reducing hunger and food insecurity in developing countries. Using cross-sectional data obtained from a survey conducted during 2013 crop season, we performed a probit model (plot-level analysis) to determine the probability of adopting new improved rice varieties (NIRVs) by smallholder farmers particularly from two main agro-ecological regions (hills and tropical plain terai regions) of Central Nepal. The results revealed that education, extension services and seed access play significant roles in adoption decisions. Additionally, farm and field characteristic variables such as farm size, endowment of favorable land type (e.g. lowlands), and animal power (e.g. oxen) are the key factors influencing the probability of adopting NIRVs. The results showed that technology specific variables (e.g. yield potential and acceptability) are significant for explaining adoption behavior, implying that it is important to take farmers' preferences to varietal characteristics into consideration in the design of a research and development program. Given the significant role played by extension and access related variables, increased emphasis on information dissemination, field demonstration, and farmers' participatory research and training programs to popularize new rice varieties and enhance their adoption rate are required. This also suggests that policy intervention should be made on improving the educational status of farming households, and developing programs on varietal package of rice seed which offer farmers a variety of choices among the appropriate pools of germplasm. Such programs ultimately help farmers develop more profit-oriented behavior which are necessary to enhance adoption rate, production and food security in the long run.展开更多
To enhance the yield potential of an elite indica rice cultivar,an introgression(BC_3-derived) line of IR64,YTH288,was developed using a new-plant-type cultivar,IR66215-44-2-3,as a donor parent.YTH288 has agronomicall...To enhance the yield potential of an elite indica rice cultivar,an introgression(BC_3-derived) line of IR64,YTH288,was developed using a new-plant-type cultivar,IR66215-44-2-3,as a donor parent.YTH288 has agronomically valuable characteristics such as large panicles,few unproductive tillers,and large leaves inherited from NPT.To identify the genetic basis of these traits,we used 167 F_2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits:days to heading(DTH),culm length(CL),flag leaf length(FLL),flag leaf width(FLW),and filled spikelet number per panicle(FSN).Six putative QTL were detected:four on chromosome4(for CL,FLL,FLW,and FSN) and two on chromosome 2(for DTH and FLL).All QTL with the IR66215-44-2-3 allele,except that for FLL on chromosome 2,had positive effects on each trait.To confirm the effects of these putative QTL,we developed NILs with the IR64 genetic background by marker-assisted selection.We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4.Additionally,four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropic To enhance the yield potential of an elite indica rice cultivar, an introgression(BC3-derived) line of IR64, YTH288, was developed using a new-plant-type cultivar,IR66215-44-2-3, as a donor parent. YTH288 has agronomically valuable characteristics such as large panicles, few unproductive tillers, and large leaves inherited from NPT.To identify the genetic basis of these traits, we used 167 F2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits: days to heading(DTH), culm length(CL), flag leaf length(FLL), flag leaf width(FLW), and filled spikelet number per panicle(FSN). Six putative QTL were detected: four on chromosome4(for CL, FLL, FLW, and FSN) and two on chromosome 2(for DTH and FLL). All QTL with the IR66215-44-2-3 allele, except that for FLL on chromosome 2, had positive effects on each trait. To confirm the effects of these putative QTL, we developed NILs with the IR64 genetic background by marker-assisted selection. We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4. Additionally, four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropiceffects for unique agronomic traits. These NILs can be used as research materials for studying each trait and as breeding materials for yield improvement of indica rice cultivars.展开更多
Forty pairs of SSR markers were used to compare the genetic diversity changes in 151 Chinese major rice varieties planted in 1950s and in the recent ten years. Of 40 SSR loci, 39 were found to be polymorphic while one...Forty pairs of SSR markers were used to compare the genetic diversity changes in 151 Chinese major rice varieties planted in 1950s and in the recent ten years. Of 40 SSR loci, 39 were found to be polymorphic while one locus (RM479) monomorphic. A total of 213 alleles were identified from the 39 polymorphic loci. The average number of alleles per locus (Na) was of 5.5, ranging from 2 to 11. Nei's gene diversity index (He) varied drastically among loci from 0.309 at RM174 to 0.869 at RM418, with an average value of 0.649. There existed significant difference in SSR allelic diversity between indica and japonica subspecies, and indica had more variation than japonica both in Na and He. By comparison with the genetic changes in Na and He, it was revealed that the varieties planted in 1950s had more alleles and higher He than those in the recent ten years both for indica and japonica rices. The difference between two subspecies for Na was significant in a tendency over time (indica: z = 2.677, P = 0.007; japonica: z = 3.441, P = 0.001), but not significant for He (indica: z = 1.471, P = 0.141; japonica: z = 1.932, P = 0.053). Analysis of molecular variance (AMOVA) indicated that there existed significant difference (P 〈 0.05) in genetic variation between the two periods, of which more genetic variation was contributed by indica (Fst= 0.050) and japonica (Fst= 0.082) subsets. Using locus-by-locus AMOVA procedure, significant genetic differentiations were observed in 13 loci (RM21, RM128, RM147, RM169, RM190, RM221, RM231, RM251, RM253, RM317, RM341, RM418, and RM478) for indica varieties and 11 loci (RM101, RM135, RM152, RM159, RM169, RM190, RM251, RM253, RM311, RM418, and RM478) for japonica ones between the two periods. It was found some alleles had been lost in current major rice varieties as comparing with those in 1950s. Therefore, it should be necessary to exploit more alien elite genetic resources for extension of genetic background in current rice breeding program.展开更多
Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance...Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm^–1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm^–1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and root bleedings at grain filling stage during the improvement of mid-season indica rice.展开更多
Sixty-three major inbred varieties and parental lines of major F1 hybrids used in the commercial rice production in China were assayed with rice microsatellites screened in a previous study and additional microsatelli...Sixty-three major inbred varieties and parental lines of major F1 hybrids used in the commercial rice production in China were assayed with rice microsatellites screened in a previous study and additional microsatellites on four chromosomes. A set of 24 markers was selected and proposed for its application in the variety identification of rice, which are distributed on all the 12 rice chromosomes with 2 markers on each chromosome. The 63 major varieties and parental lines, as well as 41 major F1 hybrids, were genotyped with the markers. Alleles detected in each line at each marker locus were verified. By matching marker genotypes of corresponding F1, maternal and paternal lines of hybrid rice, high reliability of the maternal lines was verified, data on the paternal lines were modified, and a false hybrid was removed. A database containing genotype data of 103 major rice vadeties and parental lines at the 24 marker loci was constructed and analyzed.展开更多
Labor scarcity requires double-season rice to be planted by direct seeding as an alternative to transplanting. Only ultrashort-duration varieties can be used in direct-seeded, double-season rice(DSD) in central China ...Labor scarcity requires double-season rice to be planted by direct seeding as an alternative to transplanting. Only ultrashort-duration varieties can be used in direct-seeded, double-season rice(DSD) in central China where thermal time is limited. Whether ultrashort-duration varieties grown in DSD can be as productive and efficient in nitrogen(N) use as transplanted double-season rice(TPD) remains unclear. Field experiments were conducted in Hubei province, central China with two establishment methods(DSD,TPD) and three N rates in the early and late seasons of 2017 and 2018. Nitrogen treatments included zero-N control(N0), total N rate of 60 kg N ha;with equal splits at basal, midtillering, and panicle initiation(N1), and weekly N application at 15 kg ha;from seeding/transplanting to heading(N2). Both early-and late-season rice under DSD matured within 95 days, on average 9 days shorter than rice under TPD. The grain yield of DSD was comparable to or higher than that of TDP in both seasons, although the daily yield was significantly higher under DSD than under TDP. Before heading, DSD had higher leaf area,stem number, intercepted radiation, and radiation use efficiency than TPD, which compensated for the negative effect of short growth duration on biomass production. Total dry weight and harvest index under DSD were comparable to or higher than those under TDP. In general, the recovery efficiency of fertilizer-N under DSD was higher than that under TPD, but the reverse was true for physiological N use efficiency. Thus, there was no significant difference in agronomic N use efficiency between DSD and TPD. These results suggested that DSD with ultrashort-duration varieties is a promising alternative to TPD in central China for maintaining high grain yield and N fertilizer use efficiency with less labor input.展开更多
Pot experiment was conducted at the Botanical Garden of the Department of Biological Science, Usmanu Danfodiyo University, Sokoto Nigeria, during the 2013 dry season. The main objective of this research was to determi...Pot experiment was conducted at the Botanical Garden of the Department of Biological Science, Usmanu Danfodiyo University, Sokoto Nigeria, during the 2013 dry season. The main objective of this research was to determine the effect of water stress and variety on productivity of rice (Oryza sativa) at Sokoto. The treatment consisted of water stress at three growth stages (Tillering, flowering, Grain filling) and unstress (control) and three rice varieties (FARO 44, NERICA 2 and FARO 15) laid out in a Completely Randomised Design (CRD) replicated three times. The result indicated that water stress significantly (P < 0.05) resulted to decreased in plant height, number of leaves per plant, total biomass, harvest index and grain yield. The results indicated significant (P < 0.05) differences among genotypes. Faro 44 differed significant from in plant height, number of leaves per plant, total biomass, harvest index and grain yield. FARO 44 differed significantly from NERICA 2 and FARO 15 at all the parameters under study. Water is very vital as far as rice production is concern should be applied at every stage of rice production. FARO 44 is recommended for the area for higher yield.展开更多
There exists a single nucleotide polymorphism, G or T, at the first base of the donor splice site of waxy gene intron 1 in rice. In order to study the relationship between the first base of the donor splice site of wa...There exists a single nucleotide polymorphism, G or T, at the first base of the donor splice site of waxy gene intron 1 in rice. In order to study the relationship between the first base of the donor splice site of waxy gene intron 1 and amylose content in rice, the one-step PCR method was used to determine whether it is G or T in 220 Yunnan indigenous rice varieties from 14 districts, 55 towns/counties of Yunnan Province, and 101 varieties of which were validated by the PCR-Acc I method. According to the G/T polymorphism, 164 rice varieties showed GG-genotype, while the other 56 fell into TT- genotype, accounting for 74.5% and 25.5% of all the test varieties, respectively. When all the rice varieties were divided into indica and japonica subspecies, it was found that 80.5% of indica rice and 67.0% of japonica rice belonged to GG-genotype. The rice varieties with GG-genotype had significantly higher amylose content (18.95% on average) than those with TT- genotype (all below 16%), but 33 rice varieties with GG-genotype still had low amylose content ranging from 3.91% to 15.93%, and most of them came from the Dai minority area in the Southwest of Yunnan Province. However, there was no significant difference in the mean amylose content of the same GG or TT genotypes between indica and japonica rice, suggesting that different genetic backgrounds, indica or japonica, had no effect on amylose content. The coefficient of correlation between the genotype and amylose content was 0.733 (P〈0.01).展开更多
The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampli...The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampling technique participated in the survey. The Cragg's Double hurdle model was used to model the determinants of adoption and intensity of adoption of MVs of rice, and the propensity score matching was used to analyze the impact of adoption on poverty. The results showed that age, education, risk aversion, land size, yield, perception of MVs as high yielding, resistant to diseases and availability of MVs positively influenced the decision to adopt. However, variables such as household size, experience of a farmer, off-farm job participation, amount of credit received, cost of seeds, insecticides and fertilizers negatively influenced the adoption of MVs. Intensity of adoption of MVs was negatively influenced by experience of a farmer, cost of fertilizer and marketability of MVs, and positively affected by household size, risk aversion, land size, cost of insecticides, perception of MVs as high yielding and availability of MV seeds. Poverty incidence, gap and severity were high among non-adopters to adopters of MVs. After matching adopters and non-adopters of MV groups using four different algorithms of nearest neighbour matching, stratification matching, radius matching and kernel matching, the impact of MV adoption resulted in higher per capita monthly household expenditure by about US$ 52.82 to US$ 63.17.展开更多
The use of nitrogen(N)-efficient rice(Oryza sativa L.) varieties could reduce excessive N input without sacrificing yields. However, the plant traits associated with N-efficient rice varieties have not been fully defi...The use of nitrogen(N)-efficient rice(Oryza sativa L.) varieties could reduce excessive N input without sacrificing yields. However, the plant traits associated with N-efficient rice varieties have not been fully defined or comprehensively explored. Here, three japonica N-efficient varieties(NEVs) and three japonica N-inefficient varieties(NIVs) of rice were grown in a paddy field under N omission(0 N, 0 kg N ha^(-1)) and normal N(NN, 180 or 200 kg N ha^(-1)) treatments. Results showed that NEVs exhibited higher grain yield and nitrogen use efficiency(NUE) than NIVs under both treatments, due to improved sink size and filled-grains percentage in the former which had higher root oxidation activity and greater root dry weight, root length and root diameter at panicle initiation(PI), as well as higher spikelet-leaf ratio and more productive tillers during the grain-filling stage. Compared with NIVs, NEVs also exhibited enhanced N translocation and dry matter accumulation after heading and improved flag leaf morpho-physiological traits, including greater leaf thickness and specific leaf weight and higher contents of ribulose^(-1),5-bisphosphate carboxylase/oxygenase, chlorophyll, nitrogen, and soluble sugars, leading to better photosynthetic performance. Additionally, NEVs had a better canopy structure, as reflected by a higher ratio of the extinction coefficient for effective leaf N to the light extinction coefficient, leading to enhanced canopy photosynthesis and dry matter accumulation. These improved agronomic and physiological traits were positively and significantly correlated with grain yield and internal NUE, which could be used to select and breed N-efficient rice varieties.展开更多
With 5 rice varieties( Yifeng 3321,Yifeng 3315,Yifeng 3317,Yifeng 45,Yifeng 14-24) as the experimental objects,the aseptic seedling method was used to culture the rice seeds,and the HPLC was used to determine the cont...With 5 rice varieties( Yifeng 3321,Yifeng 3315,Yifeng 3317,Yifeng 45,Yifeng 14-24) as the experimental objects,the aseptic seedling method was used to culture the rice seeds,and the HPLC was used to determine the content of amino acids in aseptic rice seedlings as well as the total content of 8 kinds of essential amino acids and the content of protein. And the content of protein and amino acids in the polished rice of 5 varieties was detected,and the analysis of variance was performed for screening of the varieties containing high essential amino acids. The rice with high essential amino acids could be produced to meet people's rice quality requirements. The analysis of variance indicated that there were significant differences( F = 39. 262,p = 0. 01) in the content of essential amino acids among 5 kinds of rice varieties. By the Duncan's multiple comparison,the differences among rice varieties were calculated to obtain screening results. The aseptic seedlings:Yifeng 3321(7. 268),Yifeng 3315(6. 395),Yifeng 3317(5. 698),Yifeng 45(5. 567),Yifeng 14-24(5. 190). Rice: Yifeng 3321(2.998),Yifeng 14-24(2. 627),Yifeng 3317(2. 611),Yifeng 3315(2. 503),Yifeng 45(2. 281). Based on the estimated human daily requirement of essential amino acids and amino acids requirement pattern,it was found that the polished rice of 5 varieties was up to standard.The variety with the highest content of essential amino acids was Yifeng 3317(3830 mg/100g),followed by Yifeng 3321(3770 mg/100 g).The results showed that the high quality rice variety in this experiment was Yifeng 3321.展开更多
Yield test of 41 entries, 32 new hybrids, 8 male parents restore lines and 1 inbred variety, was conducted on the farm of University of Arkansas at Pine Bluff (UAPB) in 2012. The only inbred Francis in this experiment...Yield test of 41 entries, 32 new hybrids, 8 male parents restore lines and 1 inbred variety, was conducted on the farm of University of Arkansas at Pine Bluff (UAPB) in 2012. The only inbred Francis in this experiment was used as the check. Francis is a popular variety and widely used in Arkansas rice production. Results showed that the yields of 7 hybrids were 25.7% - 30.7% higher than check Francis. Hybrid 28s/BP23R had the highest yield, 10846.6 kg/hectare and over check by 30.7%. The yield of hybrid 28s/PB-24, was 10628.9 kg/hectare and over check by 28.1%. The yields of hybrid 28s/PB-22 and 33A/PB24 were 10549.8 and 10539.8 kg/hectare and over check by 27.1% and 27.0%, respectively. The sterile lines 28s, 29s, 30s and 33A have good combinability. PB2, PB5, PB12, PB22, PB23, PB24, and PB25 are good restorers and most of their hybrids were over check more than 17%. Sterile 28s has DEMG (Dominant Early Maturity Gene) which can make earlier heading hybrids by crossing with late restorer lines. Sterile 30s and 33A have no DEMG but have heat resistant gene. They can make late heading hybrids by crossing with late restorer lines PB24 and PB22 and the late heading hybrids can resistant to hot temperature. These results showed that these sterile lines, restorer lines and hybrids can be used in rice production of Arkansas in the future.展开更多
文摘Improved rice varieties(IRVs)play a significant role in establishing food security and improving livelihood in the Global South since its introduction in the 1960s.However,the adoption of new IRVs has remained relatively low.This low adoption poses a challenge to rice-producing and consuming countries as they are increasingly threatened by production shortages,malnutrition,and poor rice quality.Many empirical studies have attempted to identify the determinants influencing the adoption of IRVs by distinguishing the characteristics between adopters and non-adopters.This review showed a consensus on the important determinants influencing the adoption of IRVs in the Global South.Findings synthesized from 99 studies suggested that variables(farm size,education,information access and farm location)examined extensively are not necessarily the most important determinants of adoption when undertaking a weighted analysis.Terrain,source of seed and technology-related attributes(perceived yield,maturity,ease of use,marketability and technical efficiency)are more important determinants of adoption,with determinants changing according to adoption type(probability or intensity of adoption),variety type and region.The recommendations for future adoption studies include:incorporating more technology-specific variables,increasing research for overlooked regions and variety types,shifting away from predominant static analysis by capturing the dynamics of the adoption process,and considering the potential biases in analyses.This review will facilitate the development of targeted interventions and policies that promote IRV adoption in the Global South.
文摘In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.
基金Supported by Loudi City Science and Technology Project(2014-1)State Key Laboratory of Hybrid RiceKey Laboratory of Pesticide Harmless Application of Hunan Province~~
文摘The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germination rate, shooting index, vigor index, seedling and shoot lengths, and fresh weights. The results showed that as Cd concentration grew, seed germination and seedling growth kept increasingly inhibited; germination index, vigor index, root length, shoot length and fresh weights went down; inhibition effects on seed germination and seedling growth were conventional rice〉two-line hybrid rice〉three-line hybrid ,rice. Shanyou 9588, Tianyou 998, Chuanxiang 8, and Y Liangyou 1 performed ~rongly in Cd tolerance; C Liangyou 651, Nei 5 You 263, Xiangwanxian 16, Huanghuazhan, Xiangwanxian 13, and Zhunliangyou 527 performed poorly in Cd tolerance, and Cd tolerance of rest treatments were moderate.
基金Supported by Social Undertaking and People's Livelihood Guarantee Science and Technology Innovation Fund(cstc2016shms-ztzx0013cstc2016shms-ztzx0032 and cstc2016shms-ztzx0017)~~
文摘The nationally registered rice varieties during 2006-2015 were analyzed and there were 49.4 varieties on average annually registered in the last decade. In terms of the structure of varieties, there was a decreasing trend for the proportion of three-line hybrid rice varieties but a rapid increase for that of two-line hybrid rice varieties. The percentage of rice varieties developed by scientific research institu- tions was decreasing but that developed by seed companies kept a rapid increase, indicating the commercial breeding conducted by seed companies has become a principal model in rice breeding. With regard to grain quality of varieties, the con- ventional rice varieties showed an increasing trend while the hybrid rice varieties had a decreasing trend in the proportion of high quality varieties, indicating hybrid rice needs improving more in grain quality in breeding programs.
基金Supported by National"Twelfth Five-Year"Plan for Science&Technology Support(2011BAD16B04)Super High-yielding Rice and"555"Talent Leading Program of Jiangxi Province~~
文摘The research selected 16 rice varieties(8 early and 8 late double-cropping rice) by mechanical transplanting modes as per equivalent row and wide-narrow row to explore yield and physiological traits in order to provide references for selection of rice variety suitable for mechanical transplanting. The results showed that yields of early and late rice improved by 2.90% and 2.73% by mechanical transplanting as per equivalent row and wide-narrow row respectively. Besides, leaf area index in the treatment as per wide-narrow row was higher compared with the treatment as per equivalent row, as well as average photosynthetic potential which grew by 0.92%,3.99% and 5.64% of early from tillering-peak stage to mature stage and 3.46%,7.09% and 6.79% of late rice. Furthermore, by mechanical transplanting as per wide-narrow row, SPAD value, and root activity performer higher, as well as the number of differentiated branch and glumous flowers, but degradation rate showed lower. In addition, with mechanical transplanting the same, early rice Zhuliangyou819 and late rice Fengyuanyou 299 took advantages in yield, which can be priorities for mechanical transplanting in double-cropping areas in Jiangxi Province.
基金supported by the National Basic Research Program of China (2011CB100406)the Science and Technology Department of Zhejiang Province,China(2008C12064)+2 种基金the Ministry of Environment Protection of China (201090020)the Wenzhou Bureau of Science and Technology of Zhejiang Province,China(N20080024)the Key Laboratory of Non-Point Sources Pollution Control,Ministry of Agriculture of China (KYJD09021)
文摘The traditional rice-fish farming system is selected as a "globally important agricultural heritage system" (GIAHS) by the Food and Agriculture Organization (FAO),United Nations Development Programme (UNDP),and Global Environment Facility (GEF),etc.In Zhejiang Province of China,where the pilot site for this GIAHS farming system is located,we compared the use of traditional rice varieties in rice-fish co-culture and rice monoculture.Further,we determined how traditional rice varieties were performed in this rice-fish system.Only 19% of the farmers who practiced rice monoculture planted traditional varieties while 52% of farmers who practiced rice-fish co-culture planted traditional varieties.Traditional varieties represented 13% of the total land cultivated under rice in the rice-fish system but only 2% in the rice monoculture system.In the rice-fish system,yield was lower for traditional rice varieties than hybrid varieties but application of fertilizers and pesticides was also lower.In a field experiment in the rice-fish system without pesticides,rice planthopper numbers and sheath blight incidence were lower from three traditional varieties than one hybrid variety;yields were 8 to 32% lower from the traditional varieties than the hybrid.Our results showed that traditional rice varieties can be preserved through conserving GIAHS rice-fish co-culture.Our study also indicated that traditional rice varieties can survive in the rice-fish system because these varieties are helpful to the whole system and beneficial to the farmers.
基金supported by the grants from the National Natural Science Foundation of China (31571986)the National Basic Research Programme of China (2013CB127502)
文摘The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa (aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica). Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly (r=0.87, P≤0.05) with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 (aus), Shenliangyou 1 (hybrid aus) and Cliangyou 4418 (hybrid indica) were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.
文摘The use of improved high yielding crop varieties is an important avenue for reducing hunger and food insecurity in developing countries. Using cross-sectional data obtained from a survey conducted during 2013 crop season, we performed a probit model (plot-level analysis) to determine the probability of adopting new improved rice varieties (NIRVs) by smallholder farmers particularly from two main agro-ecological regions (hills and tropical plain terai regions) of Central Nepal. The results revealed that education, extension services and seed access play significant roles in adoption decisions. Additionally, farm and field characteristic variables such as farm size, endowment of favorable land type (e.g. lowlands), and animal power (e.g. oxen) are the key factors influencing the probability of adopting NIRVs. The results showed that technology specific variables (e.g. yield potential and acceptability) are significant for explaining adoption behavior, implying that it is important to take farmers' preferences to varietal characteristics into consideration in the design of a research and development program. Given the significant role played by extension and access related variables, increased emphasis on information dissemination, field demonstration, and farmers' participatory research and training programs to popularize new rice varieties and enhance their adoption rate are required. This also suggests that policy intervention should be made on improving the educational status of farming households, and developing programs on varietal package of rice seed which offer farmers a variety of choices among the appropriate pools of germplasm. Such programs ultimately help farmers develop more profit-oriented behavior which are necessary to enhance adoption rate, production and food security in the long run.
基金the results obtained from phases Ⅲ , Ⅳ, Ⅴ, and Ⅵ of the IRRI – Japan Collaborative Research Project, which was supported by the Ministry of Foreign Affairs and the Ministry of Agriculture, Forestry and Fisheries of Japan
文摘To enhance the yield potential of an elite indica rice cultivar,an introgression(BC_3-derived) line of IR64,YTH288,was developed using a new-plant-type cultivar,IR66215-44-2-3,as a donor parent.YTH288 has agronomically valuable characteristics such as large panicles,few unproductive tillers,and large leaves inherited from NPT.To identify the genetic basis of these traits,we used 167 F_2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits:days to heading(DTH),culm length(CL),flag leaf length(FLL),flag leaf width(FLW),and filled spikelet number per panicle(FSN).Six putative QTL were detected:four on chromosome4(for CL,FLL,FLW,and FSN) and two on chromosome 2(for DTH and FLL).All QTL with the IR66215-44-2-3 allele,except that for FLL on chromosome 2,had positive effects on each trait.To confirm the effects of these putative QTL,we developed NILs with the IR64 genetic background by marker-assisted selection.We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4.Additionally,four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropic To enhance the yield potential of an elite indica rice cultivar, an introgression(BC3-derived) line of IR64, YTH288, was developed using a new-plant-type cultivar,IR66215-44-2-3, as a donor parent. YTH288 has agronomically valuable characteristics such as large panicles, few unproductive tillers, and large leaves inherited from NPT.To identify the genetic basis of these traits, we used 167 F2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits: days to heading(DTH), culm length(CL), flag leaf length(FLL), flag leaf width(FLW), and filled spikelet number per panicle(FSN). Six putative QTL were detected: four on chromosome4(for CL, FLL, FLW, and FSN) and two on chromosome 2(for DTH and FLL). All QTL with the IR66215-44-2-3 allele, except that for FLL on chromosome 2, had positive effects on each trait. To confirm the effects of these putative QTL, we developed NILs with the IR64 genetic background by marker-assisted selection. We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4. Additionally, four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropiceffects for unique agronomic traits. These NILs can be used as research materials for studying each trait and as breeding materials for yield improvement of indica rice cultivars.
文摘Forty pairs of SSR markers were used to compare the genetic diversity changes in 151 Chinese major rice varieties planted in 1950s and in the recent ten years. Of 40 SSR loci, 39 were found to be polymorphic while one locus (RM479) monomorphic. A total of 213 alleles were identified from the 39 polymorphic loci. The average number of alleles per locus (Na) was of 5.5, ranging from 2 to 11. Nei's gene diversity index (He) varied drastically among loci from 0.309 at RM174 to 0.869 at RM418, with an average value of 0.649. There existed significant difference in SSR allelic diversity between indica and japonica subspecies, and indica had more variation than japonica both in Na and He. By comparison with the genetic changes in Na and He, it was revealed that the varieties planted in 1950s had more alleles and higher He than those in the recent ten years both for indica and japonica rices. The difference between two subspecies for Na was significant in a tendency over time (indica: z = 2.677, P = 0.007; japonica: z = 3.441, P = 0.001), but not significant for He (indica: z = 1.471, P = 0.141; japonica: z = 1.932, P = 0.053). Analysis of molecular variance (AMOVA) indicated that there existed significant difference (P 〈 0.05) in genetic variation between the two periods, of which more genetic variation was contributed by indica (Fst= 0.050) and japonica (Fst= 0.082) subsets. Using locus-by-locus AMOVA procedure, significant genetic differentiations were observed in 13 loci (RM21, RM128, RM147, RM169, RM190, RM221, RM231, RM251, RM253, RM317, RM341, RM418, and RM478) for indica varieties and 11 loci (RM101, RM135, RM152, RM159, RM169, RM190, RM251, RM253, RM311, RM418, and RM478) for japonica ones between the two periods. It was found some alleles had been lost in current major rice varieties as comparing with those in 1950s. Therefore, it should be necessary to exploit more alien elite genetic resources for extension of genetic background in current rice breeding program.
基金This work was supported by the National Key Research and Development Program of China(2016YFD0300206-4,2017YFD0301206 and 2018YFD0300801)the National Natural Science Foundation of China(31671614 and 31871559)+3 种基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Six Talent Peaks Project in Jiangsu Province,China(SWYY-151)the Jiangsu Agriculture Science and Technology Innovation Fund,China(CX(18)3007)the Top Talent Support Plan of Yangzhou University,China(2015-01).
文摘Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm^–1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm^–1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and root bleedings at grain filling stage during the improvement of mid-season indica rice.
文摘Sixty-three major inbred varieties and parental lines of major F1 hybrids used in the commercial rice production in China were assayed with rice microsatellites screened in a previous study and additional microsatellites on four chromosomes. A set of 24 markers was selected and proposed for its application in the variety identification of rice, which are distributed on all the 12 rice chromosomes with 2 markers on each chromosome. The 63 major varieties and parental lines, as well as 41 major F1 hybrids, were genotyped with the markers. Alleles detected in each line at each marker locus were verified. By matching marker genotypes of corresponding F1, maternal and paternal lines of hybrid rice, high reliability of the maternal lines was verified, data on the paternal lines were modified, and a false hybrid was removed. A database containing genotype data of 103 major rice vadeties and parental lines at the 24 marker loci was constructed and analyzed.
基金supported by the National Natural Science Foundation of China(31971845,32061143038)the China Postdoctoral Science Foundation(2021 M691179)+3 种基金the China Agriculture Research System(CARS-01-20)the Program of Introducing Talents of Discipline to Universities in China(the 111 Project no.B14032)the Program for Changjiang Scholars and Innovative Research Team in University of China(IRT1247)a grant from the Bill and Melinda Gates Foundation(OPP51587)。
文摘Labor scarcity requires double-season rice to be planted by direct seeding as an alternative to transplanting. Only ultrashort-duration varieties can be used in direct-seeded, double-season rice(DSD) in central China where thermal time is limited. Whether ultrashort-duration varieties grown in DSD can be as productive and efficient in nitrogen(N) use as transplanted double-season rice(TPD) remains unclear. Field experiments were conducted in Hubei province, central China with two establishment methods(DSD,TPD) and three N rates in the early and late seasons of 2017 and 2018. Nitrogen treatments included zero-N control(N0), total N rate of 60 kg N ha;with equal splits at basal, midtillering, and panicle initiation(N1), and weekly N application at 15 kg ha;from seeding/transplanting to heading(N2). Both early-and late-season rice under DSD matured within 95 days, on average 9 days shorter than rice under TPD. The grain yield of DSD was comparable to or higher than that of TDP in both seasons, although the daily yield was significantly higher under DSD than under TDP. Before heading, DSD had higher leaf area,stem number, intercepted radiation, and radiation use efficiency than TPD, which compensated for the negative effect of short growth duration on biomass production. Total dry weight and harvest index under DSD were comparable to or higher than those under TDP. In general, the recovery efficiency of fertilizer-N under DSD was higher than that under TPD, but the reverse was true for physiological N use efficiency. Thus, there was no significant difference in agronomic N use efficiency between DSD and TPD. These results suggested that DSD with ultrashort-duration varieties is a promising alternative to TPD in central China for maintaining high grain yield and N fertilizer use efficiency with less labor input.
文摘Pot experiment was conducted at the Botanical Garden of the Department of Biological Science, Usmanu Danfodiyo University, Sokoto Nigeria, during the 2013 dry season. The main objective of this research was to determine the effect of water stress and variety on productivity of rice (Oryza sativa) at Sokoto. The treatment consisted of water stress at three growth stages (Tillering, flowering, Grain filling) and unstress (control) and three rice varieties (FARO 44, NERICA 2 and FARO 15) laid out in a Completely Randomised Design (CRD) replicated three times. The result indicated that water stress significantly (P < 0.05) resulted to decreased in plant height, number of leaves per plant, total biomass, harvest index and grain yield. The results indicated significant (P < 0.05) differences among genotypes. Faro 44 differed significant from in plant height, number of leaves per plant, total biomass, harvest index and grain yield. FARO 44 differed significantly from NERICA 2 and FARO 15 at all the parameters under study. Water is very vital as far as rice production is concern should be applied at every stage of rice production. FARO 44 is recommended for the area for higher yield.
文摘There exists a single nucleotide polymorphism, G or T, at the first base of the donor splice site of waxy gene intron 1 in rice. In order to study the relationship between the first base of the donor splice site of waxy gene intron 1 and amylose content in rice, the one-step PCR method was used to determine whether it is G or T in 220 Yunnan indigenous rice varieties from 14 districts, 55 towns/counties of Yunnan Province, and 101 varieties of which were validated by the PCR-Acc I method. According to the G/T polymorphism, 164 rice varieties showed GG-genotype, while the other 56 fell into TT- genotype, accounting for 74.5% and 25.5% of all the test varieties, respectively. When all the rice varieties were divided into indica and japonica subspecies, it was found that 80.5% of indica rice and 67.0% of japonica rice belonged to GG-genotype. The rice varieties with GG-genotype had significantly higher amylose content (18.95% on average) than those with TT- genotype (all below 16%), but 33 rice varieties with GG-genotype still had low amylose content ranging from 3.91% to 15.93%, and most of them came from the Dai minority area in the Southwest of Yunnan Province. However, there was no significant difference in the mean amylose content of the same GG or TT genotypes between indica and japonica rice, suggesting that different genetic backgrounds, indica or japonica, had no effect on amylose content. The coefficient of correlation between the genotype and amylose content was 0.733 (P〈0.01).
基金supported by Federation of Indian Chambers of Commerce & Industry (2017–2018) through the Government of India under CV Raman Post-Doctoral Fellowship for African Researchers
文摘The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampling technique participated in the survey. The Cragg's Double hurdle model was used to model the determinants of adoption and intensity of adoption of MVs of rice, and the propensity score matching was used to analyze the impact of adoption on poverty. The results showed that age, education, risk aversion, land size, yield, perception of MVs as high yielding, resistant to diseases and availability of MVs positively influenced the decision to adopt. However, variables such as household size, experience of a farmer, off-farm job participation, amount of credit received, cost of seeds, insecticides and fertilizers negatively influenced the adoption of MVs. Intensity of adoption of MVs was negatively influenced by experience of a farmer, cost of fertilizer and marketability of MVs, and positively affected by household size, risk aversion, land size, cost of insecticides, perception of MVs as high yielding and availability of MV seeds. Poverty incidence, gap and severity were high among non-adopters to adopters of MVs. After matching adopters and non-adopters of MV groups using four different algorithms of nearest neighbour matching, stratification matching, radius matching and kernel matching, the impact of MV adoption resulted in higher per capita monthly household expenditure by about US$ 52.82 to US$ 63.17.
基金supported by the grants from the National Natural Science Foundation of China(32071843,31901444 and 31901445)the National Key Research and Development Program of China(2016YFD0300206-4 and 2018YFD0300800)+3 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)the Top Talent Supporting Program of Yangzhou University,China(2015-01)the Natural Science Foundation of Jiangsu Province,China(BK20190880)the Natural Science Foundation of Jiangsu Higher Education Institutions,China(19KJB210019)。
文摘The use of nitrogen(N)-efficient rice(Oryza sativa L.) varieties could reduce excessive N input without sacrificing yields. However, the plant traits associated with N-efficient rice varieties have not been fully defined or comprehensively explored. Here, three japonica N-efficient varieties(NEVs) and three japonica N-inefficient varieties(NIVs) of rice were grown in a paddy field under N omission(0 N, 0 kg N ha^(-1)) and normal N(NN, 180 or 200 kg N ha^(-1)) treatments. Results showed that NEVs exhibited higher grain yield and nitrogen use efficiency(NUE) than NIVs under both treatments, due to improved sink size and filled-grains percentage in the former which had higher root oxidation activity and greater root dry weight, root length and root diameter at panicle initiation(PI), as well as higher spikelet-leaf ratio and more productive tillers during the grain-filling stage. Compared with NIVs, NEVs also exhibited enhanced N translocation and dry matter accumulation after heading and improved flag leaf morpho-physiological traits, including greater leaf thickness and specific leaf weight and higher contents of ribulose^(-1),5-bisphosphate carboxylase/oxygenase, chlorophyll, nitrogen, and soluble sugars, leading to better photosynthetic performance. Additionally, NEVs had a better canopy structure, as reflected by a higher ratio of the extinction coefficient for effective leaf N to the light extinction coefficient, leading to enhanced canopy photosynthesis and dry matter accumulation. These improved agronomic and physiological traits were positively and significantly correlated with grain yield and internal NUE, which could be used to select and breed N-efficient rice varieties.
基金Supported by Hunan Provincial Key R&D Program(2015CK3001)Changsha Key Science and Technology Project in 2015(201531)
文摘With 5 rice varieties( Yifeng 3321,Yifeng 3315,Yifeng 3317,Yifeng 45,Yifeng 14-24) as the experimental objects,the aseptic seedling method was used to culture the rice seeds,and the HPLC was used to determine the content of amino acids in aseptic rice seedlings as well as the total content of 8 kinds of essential amino acids and the content of protein. And the content of protein and amino acids in the polished rice of 5 varieties was detected,and the analysis of variance was performed for screening of the varieties containing high essential amino acids. The rice with high essential amino acids could be produced to meet people's rice quality requirements. The analysis of variance indicated that there were significant differences( F = 39. 262,p = 0. 01) in the content of essential amino acids among 5 kinds of rice varieties. By the Duncan's multiple comparison,the differences among rice varieties were calculated to obtain screening results. The aseptic seedlings:Yifeng 3321(7. 268),Yifeng 3315(6. 395),Yifeng 3317(5. 698),Yifeng 45(5. 567),Yifeng 14-24(5. 190). Rice: Yifeng 3321(2.998),Yifeng 14-24(2. 627),Yifeng 3317(2. 611),Yifeng 3315(2. 503),Yifeng 45(2. 281). Based on the estimated human daily requirement of essential amino acids and amino acids requirement pattern,it was found that the polished rice of 5 varieties was up to standard.The variety with the highest content of essential amino acids was Yifeng 3317(3830 mg/100g),followed by Yifeng 3321(3770 mg/100 g).The results showed that the high quality rice variety in this experiment was Yifeng 3321.
文摘Yield test of 41 entries, 32 new hybrids, 8 male parents restore lines and 1 inbred variety, was conducted on the farm of University of Arkansas at Pine Bluff (UAPB) in 2012. The only inbred Francis in this experiment was used as the check. Francis is a popular variety and widely used in Arkansas rice production. Results showed that the yields of 7 hybrids were 25.7% - 30.7% higher than check Francis. Hybrid 28s/BP23R had the highest yield, 10846.6 kg/hectare and over check by 30.7%. The yield of hybrid 28s/PB-24, was 10628.9 kg/hectare and over check by 28.1%. The yields of hybrid 28s/PB-22 and 33A/PB24 were 10549.8 and 10539.8 kg/hectare and over check by 27.1% and 27.0%, respectively. The sterile lines 28s, 29s, 30s and 33A have good combinability. PB2, PB5, PB12, PB22, PB23, PB24, and PB25 are good restorers and most of their hybrids were over check more than 17%. Sterile 28s has DEMG (Dominant Early Maturity Gene) which can make earlier heading hybrids by crossing with late restorer lines. Sterile 30s and 33A have no DEMG but have heat resistant gene. They can make late heading hybrids by crossing with late restorer lines PB24 and PB22 and the late heading hybrids can resistant to hot temperature. These results showed that these sterile lines, restorer lines and hybrids can be used in rice production of Arkansas in the future.