Salt stress is a critical factor affecting the growth and yield of rice.Egypt,the largest rice producer in North Africa and the Middle East,is facing contrasting challenges related to salinity in its agroecosystems.In...Salt stress is a critical factor affecting the growth and yield of rice.Egypt,the largest rice producer in North Africa and the Middle East,is facing contrasting challenges related to salinity in its agroecosystems.In this study,we compared the salt-induced responses among three rice varieties:Giza 176(Egyptian variety),Kaituodao(Chinese variety),and Pokkali(Sri Lanka variety,used as control)under normal and saline stress(100 mmol/L NaCl)conditions at two seedling stages through RNA-seq expression analysis.Giza 176 displayed a salt tolerance score of 7 on the SES(Standard Evaluation Score).Its transcriptome showed dynamic changes,with the number of upregulated genes increasing from 180 to 735,and downregulated genes increasing from 918 to 2930 from the one-week to two-week stress stages,with activated pathways in ion transport,reactive oxygen species(ROS)scavenging,and protein biosynthesis.展开更多
A rhizobox experiment with two phosphorus (P) treatments, zero-P (0 mg P kg-1) and plus-P (100 mg P kg-1) as Ca(H2PO4)2·H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of tw...A rhizobox experiment with two phosphorus (P) treatments, zero-P (0 mg P kg-1) and plus-P (100 mg P kg-1) as Ca(H2PO4)2·H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of two rice genotypes (cv. Zhongbu 51 and Pembe) different in P uptake ability and their relationship with the depletion of soil P fractions. Plant P uptake, pH, phosphatase activity, and soil P fractions in the rhizosphere were measured. Both total dry weight and total P uptake of Pembe were significantly (P < 0.05) higher than those of Zhongbu 51 in the zero-P and plus-P treatments. Significant depletions of resin-Pi, NaHCO3-Pi, NaHCO3-Po, and NaOH-Pi, where Pi stands for inorganic P and Po for organic P, were observed in the rhizosphere of both Zhongbu 51 and Pembe under both P treatments. Pembe showed a greater ability than Zhongbu 51 in depleting resin-Pi, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, and NaOH- Po in the rhizosphere. HCl-Pi and residual-P were not depleted in the rhizosphere of both genotypes, regardless of P treatments despite significant acidification in the rhizosphere of Pembe under zero-P treatment. Higher acid phosphatase (AcPME) activity and alkaline phosphatase (AlPME) activity were observed in the rhizosphere of both Zhongbu 51 and Pembe compared to the corresponding controls without plant. AcPME activity was negatively (P < 0.01) correlated to NaHCO3-Po concentration in the rhizosphere of both Zhongbu 51 and Pembe, suggesting that AcPME was associated with the mineralization of soil organic P.展开更多
A pot experiment with two rice (Oriza sativa L.) genotypes differing in internal potassium use efficiency (IKUE) was conducted under different sodium (Na) and potassium (K) levels. Adding NaCl at a proper level enhanc...A pot experiment with two rice (Oriza sativa L.) genotypes differing in internal potassium use efficiency (IKUE) was conducted under different sodium (Na) and potassium (K) levels. Adding NaCl at a proper level enhanced rice vegetative growth and increased grain yield and IKUE under low potassium. Addition of higher rate of NaCl had a negative effect on the growth of the K-efficient rice genotype, but did not for the K-inefficient genotype. Under low-K stress, higher NaCl decreased IKUE of the K-efficient rice genotype but increased IKUE for the K-inefficient genotype. At tillering stage and under low-K stress, adding NaCl increased K and Na contents and decreased the ratio of K/Na for both genotypes. At harvesting stage under low-K stress, adding NaCl increased K and Na contents and K/Na ratio for the K-efficient genotype but decreased the K/Na ratio for the K-inefficient genotype. The accumulated Na was mostly deposited in the roots and sheaths. At tillering stage, the K and Na contents and the K/Na ratios in different parts for both genotypes decreased in the following sequence: K+ in sheaths > K+ in blades > K+ in roots; Na+ in roots > Na+ in sheaths > Na+ in blades; and K/Na in sheaths 》 K/Na in roots. The K-efficient genotype had a lower K/Na ratio in roots and sheaths than the K-inefficient genotype under low-K stress. At harvesting stage, K and Na contents in grains were not affected, whereas K/Na ratio in the rice straws was increased for the K-efficient genotype but decreased for the K-inefficient genotype by Na addition. However, this was not the case under K sufficient condition.展开更多
The experiment was carried out to assess the reaction of different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild in response to the infestation by rice leaffolder （RLF）...The experiment was carried out to assess the reaction of different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild in response to the infestation by rice leaffolder （RLF）, Cnaphalocrocis medinalis （Guenee） and to explore the possible use of these genotypes in developing RLF-resistant rice varieties. The changes of various biochemical constituents such as leaf soluble protein, phenol, ortho-dihydroxy phenol, tannin and enzymes viz., peroxidase, phenyl alanine ammonia lyase （PAL） were assessed spectrophotometrically in all the rice genotypes before and after RLF infestation. The protein profile was analyzed using sodium dodecyl sulphate-poly acrylamide gel electrophoresis （SDS-PAGE） method. A significant constituent of biochemical content such as tannin, phenol and ortho-dihydroxy phenol has been increased along with enzyme activities of peroxidase and PAL in the infested resistant （Ptb 33, TKM6 and LFR831311） and wild rice genotypes （Oryza minuta and O. rhizomatis）. A decrease in leaf protein content was evident invariably in all the infested rice genotypes. It is also evident that the contents of biochemicals such as phenol, ortho- dihydroxy phenol and tannin were negatively correlated with leaffolder damage. However, leaf protein content was positively correlated with the damage by rice leaffolder. SDS-PAGE analysis for total protein profiling of healthy and C. medinalis-infested genotypes revealed the enhanced expression of a high molecular weight （〉 97 kDa） protein in all the genotypes. Besides, there was also an increased induction of a 38 kDa protein in C. medinalis infested resistant genotypes, which was absent in uninfested plants. The present investigation proved that the elevated levels of biochemicals and enzymes may play a vital role in rice plants resistance to RLF.展开更多
Folding and spinning behavior of Cnaphalocrocis medinalis （Guenee） （Lepidoptera： Pyralidae） in different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild rice genotypes...Folding and spinning behavior of Cnaphalocrocis medinalis （Guenee） （Lepidoptera： Pyralidae） in different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild rice genotypes were significantly different. Longer leaf selection time and folding time per primary fold; shorter primary fold and whole leaf fold; lower number of binds per primary fold and whole leaf fold were recorded in resistant and wild rice genotypes. In the correlation analysis, it was found that the leaf folding parameters were positively correlated to leaf folder damage whereas the leaf spinning parameters were negatively correlated. Similarly, the morphological characters differed significantly among the chosen genotypes and were related to leaffolder damage. The leaf width and total productive tiller number were positively correlated to leaffolder infestation. Results also indicated that the trichome density and length, leaf length and plant height might contribute to resistance whereas total number of green leaves had no effect on leaffolder infestation. In the scatter plot analysis between leaf folding and spinning characters and leaffolder damage, the genotypes were separated into four groups viz., resistant （TKM6, Ptb 33, LFR831311, Oryza rhizomatis and O. minuta）, moderately resistant （ASD16 and CORH1）, moderately susceptible （ADT36, Pusa Basmati and CB200290） and susceptible （IR36 and TN1）. The present investigation proved that the leaf morphology viz., leaf length and width, plant height and trichome density and length may play a vital role in resistance against rice leaffolder.展开更多
Effects of shading at the flowering and grain filling stages on osmotic regulation substance content and protective enzyme activities in the leaves of different rice genotypes （e.g., Ilyou 498, Gangyou 188, Dexiang 4...Effects of shading at the flowering and grain filling stages on osmotic regulation substance content and protective enzyme activities in the leaves of different rice genotypes （e.g., Ilyou 498, Gangyou 188, Dexiang 4103, Gangyou 527 and Chuanxiang 9838） were investigated. The results showed that the malondialdehyde content of Gangyou 188 significantly increased under shading, whereas those of Ilyou 498, Dexiang 4103, Gangyou 527 and Chuanxiang 9838 showed no significant differences compared to the control. The soluble sugar content significantly decreased in Ilyou 498, Gangyou 188, Dexiang 4103 and Chuanxiang 9838, whereas it did not significantly increase in Gangyou 527 under the weak light conditions （shading）. Moreover, the soluble protein content in the leaves of different genotypes tended to decrease under shading. Further, the protective enzyme activities in the leaves varied in different rice genotypes under the shading treatment. Based on the osmotic regulation substance content and the protective enzyme activities in the leaves of different rice genotypes, it was concluded that Gangyou 188 and Gangyou 527 had strong abilities to adapt to the low light conditions. In addition, the mechanism of damage to rice leaves in different genotypes under shading was discussed.展开更多
Ionomic profiles are primarily influenced by genetic and environmental factors.Identifying ionomic responses to varietal effects is necessary to understand the ionomic variations among species or subspecies and to pot...Ionomic profiles are primarily influenced by genetic and environmental factors.Identifying ionomic responses to varietal effects is necessary to understand the ionomic variations among species or subspecies and to potentially understand genetic effects on ionomic profiles.We cultivated 120 rice(Oryza sativa)varieties to seedling stage in identical hydroponic conditions and determined the concentrations of 26 elements(including 3 anions)in the shoots and roots of rice.Although the subspecies effects were limited by the genus Oryza pre-framework and its elemental chemical properties,we found significant differences in ionomic variations in most elements among the aus,indica and japonica subspecies.Principal component analysis of the correlations indicated that variations in the root-to-shoot ionomic transport mechanisms were the main causes of ionomic differences among the subspecies.Furthermore,the correlations were primarily associated with the screening of varieties for elemental covariation effects that can facilitate breeding biofortified rice varieties with safe concentrations of otherwise toxic elements.The japonica subspecies exhibited the strongest elemental correlations and elemental covariation effects,therefore,they showed greater advantages for biofortification than the indica and aus subspecies,whereas indica and aus subspecies were likely safer in metal(loid)polluted soils.We also found that geographical and historical distribution significantly defined the ionomic profiles.Overall,the results of this study provided a reference for further association studies to improve the nutritional status and minimize toxicity risks in rice production.展开更多
To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinc...To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinct inoculation methods（spot, filter paper and standard methods） at seedling, vegetative and reproductive stages. The results revealed that the spot and filter paper inoculation methods were successful in discerning susceptibility to the rice blast disease（P ≤ 0.05）. Disease susceptibility declined significantly from the vegetative to reproductive stages. The standard method was conducted at three different stages for pot plants grown inside the mist house. However, low temperatures did not produce disease symptoms except in a few genotypes. Among the 13 rice genotypes screened, AAT9 expressed a highly resistant response, and AAT4, AAT6, AAT10, AAT11, AAT13, AAT17 and AAT18 expressed resistance at various stages. The results will be useful for selecting elite genotypes for disease tolerance where rice blast is prevalent. In addition, the resistant genotypes can serve as a gene pool used in breeding programmes to develop new resistant genotypes.展开更多
Nutrition management is the most important for high yield production but it may affect the response of rice plants to pest and diseases due to the change of microclimate under rice plant canopy. The knowledge of nutri...Nutrition management is the most important for high yield production but it may affect the response of rice plants to pest and diseases due to the change of microclimate under rice plant canopy. The knowledge of nutrition management and its relation with pest and diseases are basis for setting up a high yield production system. Most of the pest and disease control procedures used by farmers can be considered as soil fertility management and these nutrition practices can have impact on the physiological susceptibility of crop plants to pest and diseases by affecting the plant resistance. Silicon content of plants is particularly effective against pest and diseases in rice and certain rice genotypes are more efficient accumulators of silicon, thus making them more resistant. In the absence of natural heritable resistance in rice varieties, resistance could be induced by altemate strategies to suppress certain pest and pathogens. Hence experiments were carried out in two stages during kharif 2010 and 2011 to assess the concentration of silicon in the index leaves of rice plant utilizing 133 varieties in four locations. The silica content of promising varieties ranged from 1.50% to 3.20%, 1.60% to 3.15%, 1.49% to 3.20% and 1.55% to 3.06% with a mean values of 2.50%, 2.48%, 2.51% and 2.43% at Jagtial, Warangal, Rajendranagar and Rudrur centres of Telangana region and not much variation in mean silica content in index leaves at different places. The overall yield from four locations ranged from 2,653 kg/ha to 6,860 kg/ha with a mean of 5,624 kg/ha. The yields recorded at Jagtial, Warangal, Rajendranagar and Rudrur centres ranged from 2,886 to 7,198, 2,653 to 6,831, 2,653 to 6,860 and 4,399 to 5,950 kg/ha, respectively. The lowest mean yield 5,069 kg/ha was noticed at Rudrur and the highest yield 5,940 kg/ha was found at Warangal. The variations in yields might be due to genotypic variations and also due to variations in climatic conditions of different locations.展开更多
The experiment was conducted at the Plant Physiology Laboratory (central laboratory) and Shade house of Field Laboratory of Agricultural Botany Department, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh unde...The experiment was conducted at the Plant Physiology Laboratory (central laboratory) and Shade house of Field Laboratory of Agricultural Botany Department, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh under a field experiment was also carried out on yield contributing parameters. There were three rice genotypes namely BRRI dhan55 (V<sub>1</sub>), BR6976-2B-15 (V<sub>2</sub>) and tolerant check Hashikalmi (V<sub>3</sub>) and seven water stress were imposed as treatments. The treatments were arranged for 0 days of water stress (control) irrigated continuously throughout the experimental period (T<sub>0</sub>). When the seedlings were 20 days old, water deficit was imposed for seven days (T<sub>1</sub>), when the seedlings were 35 days old, water deficit was imposed for seven days (T<sub>2</sub>), when the seedlings were 55 days old, water deficit was imposed for seven days (T<sub>3</sub>), when the seedlings were 75 days old, water deficit was imposed for seven days (T<sub>4</sub>). When the seedlings were 95 days old, water deficit was imposed for seven days (T<sub>5</sub>) and when the seedlings were 115 days old, water deficit was imposed for seven days (T<sub>6</sub>). BRRI dhan55 and Hashikalmi produced the highest tillers, grains, number of spikelets and yield. The grain sterility percentage is much higher in BR6976-2B-15 due to water stress treatment compared to other genotypes. Grain yield was the highest in BRRI dhan55 and Hashikalmi and gradually decreased with increased water stress treatment compared to other genotypes. Decreased grain yield per plant under water stress treatment reduction of tillers, panicle, filled grains, root, shoot, spikelet/panicle, panicle dry matter content, and with other causes. The harvest index was decreased due to water stress conditions in all the genotypes while less affected in BRRI dhan55 and Hashikalmi.展开更多
Insufficient N supply is an important constraint to productivity of lowland rice. Studies on N nutrition of rice cultivars with different durations representing the north western part of Indo-Gangetic Plains are scant...Insufficient N supply is an important constraint to productivity of lowland rice. Studies on N nutrition of rice cultivars with different durations representing the north western part of Indo-Gangetic Plains are scanty. A field experiment was conducted during kharif seasons of 2006 and 2007 at PAU, Ludhiana to assess the differences in grain yield and N utilization of three popular rice cultivars at varying N doses. Significant differences among genotypes were observed in grain yield, N uptake, N use efficiency and N utilization efficiency. The cultivar PAU-201 was found to be superior among all the tested genotypes. Total N uptake and grain N uptake was highest in cultivar PAU-201 followed by cultivars PR-115 and PR-113. On an average, the response to applied N for grain yield was observed upto 90 kg N ha1. Grain yield increased significantly up to 90 kg N hal in cultivars PR-115 and PAU-201 and up to 120 kg N ha1 in PR-113. Apparent recovery efficiency （ARE） and Partial factor productivity （PFPN） of N was significantly reduced at higher level of N （150 kg N hal）. It was concluded that N uptake is predominant factor in grain yield formation and cultivars differ in NUE suggesting that it may be possible to develop cultivars that are efficient at low nutrient level or are capable of using N more efficiently when applied as fertilizer.展开更多
Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice...Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type （P 〈 0.01）. The Cd concentration was higher in red paddy soil （RP） than in yellow clayey paddy soil （YP）. The average Cd concentrations of different organs in three rice types were indica 〉 hybrid 〉 japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055--0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard （0.2 mg/kg）. The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly （P 〈 0.01） correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice.展开更多
Solution culture experiments were carried out to study the NO3- uptake kinetics by rice roots and the nitrate reductase activity (NRA) in leaves of four typical rice genotypes (conventional indica, conventional japoni...Solution culture experiments were carried out to study the NO3- uptake kinetics by rice roots and the nitrate reductase activity (NRA) in leaves of four typical rice genotypes (conventional indica, conventional japonica, hybrid indica, and hybrid japonica) at different growth stages. The effects of NH4+ on the NO3- uptake kinetics was also studied. The results indicated that the four genotypes responded differently to NO3- and NH4+. Comparing indica rice with japonica rice, hybrid rice with conventional rice, formers absorbed NO3-more rapidly than laters. The superiority of indica rice and hybid rice for NO3- uptake was mainly due to the higher Vmax at the early growth stage (20 days) and the higher affinity of nitrate transporters for NO3- at the middle growth stage (50 days). At both growth stages NH4+ significantly inhibited NO3- uptake for japonica rice, but showed little effect for indica rice. Conversely, NH4+ stimulated the uptake of NO3- for hybrid rice. NH4+ could repress NRA in leaves of all four genotypes with a sensitive order as following: hybrid japonica > hybrid indica > conventional indica > conventional japonica.展开更多
Zinc(Zn) is an essential micronutrient for humans,but Zn deficiency has become serious as equally as iron(Fe) and vitamin A deficiencies nowadays.Selection and breeding of high Zn-density crops is a suitable,cost-effe...Zinc(Zn) is an essential micronutrient for humans,but Zn deficiency has become serious as equally as iron(Fe) and vitamin A deficiencies nowadays.Selection and breeding of high Zn-density crops is a suitable,cost-effective,and sustainable way to improve human health.However,the mechanism of high Zn density in rice grain is not fully understood,especially how Zn transports from soil to grains.Hydroponics experiments were carried out to compare Zn uptake and distribution in two different Zn-density rice genotypes using stable isotope technique.At seedling stage,IR68144 showed higher 68Zn uptake and transport rate to the shoot for the short-term,but no signifi-cant difference was observed in both genotypes for the long-term.Zn in xylem sap of IR68144 was consistently higher,and IR68144 exhibited higher Zn absorption ratio than IR64 at sufficient(2.0 μmol/L) or surplus(8.0 μmol/L) Zn supply level.IR64 and IR68144 showed similar patterns of 68Zn accumulation in new leaves at seedling stage and in de-veloping grains at ripening stage,whereas 68Zn in new leaves and grains of IR68144 was consistently higher.These results suggested that a rapid root-to-shoot translocation and enhanced xylem loading capacity may be the crucial processes for high Zn density in rice grains.展开更多
Genetic analysis of rolled leaf is important to rice ideotype breeding. To detect loci controlling rolled leaf of japonica restorer lines, SSR marker genotypes and phenotypes of flag leaf rolling index （LRI） were in...Genetic analysis of rolled leaf is important to rice ideotype breeding. To detect loci controlling rolled leaf of japonica restorer lines, SSR marker genotypes and phenotypes of flag leaf rolling index （LRI） were investigated in Xiushui 79 （P1, a japonica rice variety）, C Bao （P2, a japonica restorer line） and 254 recombinant inbred lines derived from the cross between P1 and P2 , and in two environments. A genetic map of this cross was constructed, QTLs for LRI were detected and their interactions with environments were analyzed. Among 818 pairs of SSR primers, 90 primers showed polymorphism between P1 and P2, and 12 markers showed highly significant correlation with LRI in both environments based on single marker regression analysis. The genetic map containing 74 information loci has a total distance of 744.6 cM, with an average of 10.1 cM between two adjacent loci. Three QTLs （qRL-1, qRL-7 and qRL-8-1） were detected with two softwares： WinQTLCart 2.5 and QTLNetwork2.0. qRL-8-1 was a new locus, accounting for 15.5% and 12.8% of phenotypic variations in the two environments, respectively. The phenotypic variation explained by additive effect was 6.6%. No interaction was found between qRL-8-1 genotype and environments.展开更多
Zinc deficiency is one of the most widespreadmicro-nutritional disorder for rice. To solve the problem, screening Zn-efficient cultivars isan available method and understanding geno-
Chalkiness is an unpleasant trait for rice con-sumer,which is known to be controlled geneti-cally and affected by environment during grainmaturing.We used the model of Additive Main
Diversity array technology （DART^TM） was a genotyping tool characterized gel-independent and high throughput. The main purpose of present study is to validate DArT for rice （Oryza sativa L.）genotyping in a high th...Diversity array technology （DART^TM） was a genotyping tool characterized gel-independent and high throughput. The main purpose of present study is to validate DArT for rice （Oryza sativa L.）genotyping in a high throughput manner. Technically, the main objective was to generate a rice general purpose gene pool, and optimize this genomic tool in order to evaluate rice germplasm genetic diversity. To achieve this, firstly, a generalpurpose DArT array was developed. Ten representatives from 24 varieties were hybridized with the general-purpose array to determine the informativeness of the clones printed on the array. The informative 1 152 clones were re-arrayed on a slide and used to fingerprint 17 of 24 germplasms. Hybridizing targets prepared from the germplasm to be assayed to the DNA array gave DNA fingerprints of germplasms. Raw data were normalized and transformed into binary data, which were then analyzed by using NTSYSpc （Numerical taxonomy system for cluster and ordination analysis, v. 2.02j） software package. The graphically displayed dendrogram derived from the array experimental data was matched with simple sequence repeats genotyping outline and varieties＇ pedigree deviation of the different varieties. Considering DArT is a sequence-independent genotyping approach, it will be applied in studies of the genetic diversity and the gene mapping of diverse of organisms, especially for those crops with less-developed molecular markers.展开更多
Background:Increasing atmospheric[CO_(2)]can increase photosynthesis and promote plant growth,consequently influencing nitrogen(N)cycling.Yet,there is no systematic information on the N response among different organs...Background:Increasing atmospheric[CO_(2)]can increase photosynthesis and promote plant growth,consequently influencing nitrogen(N)cycling.Yet,there is no systematic information on the N response among different organs of japonica and indica rice genotypes to elevated[CO_(2)]as affected by N application.To investigate the impacts of elevated[CO_(2)]and N fertilization on N uptake and utilization of different genotypic rice(Oryza sativa L.)during grain filling,a free-air CO_(2) enrichment(FACE)experiment with indica cv.Liangyou 084(IIY084)and japonica cv.Wuyunjing 23(WYJ23)was conducted in Eastern China.Crops were exposed to ambient[CO_(2)]and elevated[CO_(2)](200μmol mol^(−1) above ambient)at two levels of N:control(0N)and 22.5 g N m^(−2)(normal N,NN),and they were sampled at 82 days after transplanting(DAT),99 DAT,and maturity,respectively.Results:Under FACE,significant declines of N concentration in all tissues and the whole plants were observed with the greater decrease in leaves and stems at three stages.Positive responses of N use efficiency(NUE)to elevated[CO_(2)]were recorded over the study period.The total N accumulation remained unchanged,while a large amount of N was partitioned to panicles at the expense of leaves and stems.As compared to WYJ23,greater N transportation from roots to aboveground,especially the panicles,was observed on IIY084 accompanied by higher panicle biomass(82 DAT and 99 DAT),N concentrations(maturity),and greater NUE for leaves through the study season.Across all[CO_(2)]and cultivars,N fertilization increased N partitioning to leaves and stems while decreasing that to panicles.Additionally,N supply decreased NUE while stimulating N concentrations and N amounts of rice plants.Among all treatments,IIY084 had the highest N accumulation and allocation in panicles under elevated[CO_(2)]in combination with N fertilizer at maturity.Conclusion:Data from this study were helpful for understanding the temporal N uptake and utilization of different rice genotypes as affected by N availability and suggest that IIY084 promises a considerable prospect for its grain yield and quality under future elevated atmospheric[CO_(2)].展开更多
基金funded by the National Key R&D Program of China(Grant No.2022YFE0139400)the Egyptian-Chinese Research Fund,and Science,Technology&Innovation Funding Authority Egypt(Grant No.46512)the National Natural Science Foundation of China(Grant No.261143470).
文摘Salt stress is a critical factor affecting the growth and yield of rice.Egypt,the largest rice producer in North Africa and the Middle East,is facing contrasting challenges related to salinity in its agroecosystems.In this study,we compared the salt-induced responses among three rice varieties:Giza 176(Egyptian variety),Kaituodao(Chinese variety),and Pokkali(Sri Lanka variety,used as control)under normal and saline stress(100 mmol/L NaCl)conditions at two seedling stages through RNA-seq expression analysis.Giza 176 displayed a salt tolerance score of 7 on the SES(Standard Evaluation Score).Its transcriptome showed dynamic changes,with the number of upregulated genes increasing from 180 to 735,and downregulated genes increasing from 918 to 2930 from the one-week to two-week stress stages,with activated pathways in ion transport,reactive oxygen species(ROS)scavenging,and protein biosynthesis.
基金the National High Technology Research and Development Program (863 Program) of China(No.2001AA241025-1).
文摘A rhizobox experiment with two phosphorus (P) treatments, zero-P (0 mg P kg-1) and plus-P (100 mg P kg-1) as Ca(H2PO4)2·H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of two rice genotypes (cv. Zhongbu 51 and Pembe) different in P uptake ability and their relationship with the depletion of soil P fractions. Plant P uptake, pH, phosphatase activity, and soil P fractions in the rhizosphere were measured. Both total dry weight and total P uptake of Pembe were significantly (P < 0.05) higher than those of Zhongbu 51 in the zero-P and plus-P treatments. Significant depletions of resin-Pi, NaHCO3-Pi, NaHCO3-Po, and NaOH-Pi, where Pi stands for inorganic P and Po for organic P, were observed in the rhizosphere of both Zhongbu 51 and Pembe under both P treatments. Pembe showed a greater ability than Zhongbu 51 in depleting resin-Pi, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, and NaOH- Po in the rhizosphere. HCl-Pi and residual-P were not depleted in the rhizosphere of both genotypes, regardless of P treatments despite significant acidification in the rhizosphere of Pembe under zero-P treatment. Higher acid phosphatase (AcPME) activity and alkaline phosphatase (AlPME) activity were observed in the rhizosphere of both Zhongbu 51 and Pembe compared to the corresponding controls without plant. AcPME activity was negatively (P < 0.01) correlated to NaHCO3-Po concentration in the rhizosphere of both Zhongbu 51 and Pembe, suggesting that AcPME was associated with the mineralization of soil organic P.
基金Project (No. 315200) supported by the the Outstanding Young Scientist Grant of Natural Science Foundationof Zhejiang Pr
文摘A pot experiment with two rice (Oriza sativa L.) genotypes differing in internal potassium use efficiency (IKUE) was conducted under different sodium (Na) and potassium (K) levels. Adding NaCl at a proper level enhanced rice vegetative growth and increased grain yield and IKUE under low potassium. Addition of higher rate of NaCl had a negative effect on the growth of the K-efficient rice genotype, but did not for the K-inefficient genotype. Under low-K stress, higher NaCl decreased IKUE of the K-efficient rice genotype but increased IKUE for the K-inefficient genotype. At tillering stage and under low-K stress, adding NaCl increased K and Na contents and decreased the ratio of K/Na for both genotypes. At harvesting stage under low-K stress, adding NaCl increased K and Na contents and K/Na ratio for the K-efficient genotype but decreased the K/Na ratio for the K-inefficient genotype. The accumulated Na was mostly deposited in the roots and sheaths. At tillering stage, the K and Na contents and the K/Na ratios in different parts for both genotypes decreased in the following sequence: K+ in sheaths > K+ in blades > K+ in roots; Na+ in roots > Na+ in sheaths > Na+ in blades; and K/Na in sheaths 》 K/Na in roots. The K-efficient genotype had a lower K/Na ratio in roots and sheaths than the K-inefficient genotype under low-K stress. At harvesting stage, K and Na contents in grains were not affected, whereas K/Na ratio in the rice straws was increased for the K-efficient genotype but decreased for the K-inefficient genotype by Na addition. However, this was not the case under K sufficient condition.
文摘The experiment was carried out to assess the reaction of different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild in response to the infestation by rice leaffolder （RLF）, Cnaphalocrocis medinalis （Guenee） and to explore the possible use of these genotypes in developing RLF-resistant rice varieties. The changes of various biochemical constituents such as leaf soluble protein, phenol, ortho-dihydroxy phenol, tannin and enzymes viz., peroxidase, phenyl alanine ammonia lyase （PAL） were assessed spectrophotometrically in all the rice genotypes before and after RLF infestation. The protein profile was analyzed using sodium dodecyl sulphate-poly acrylamide gel electrophoresis （SDS-PAGE） method. A significant constituent of biochemical content such as tannin, phenol and ortho-dihydroxy phenol has been increased along with enzyme activities of peroxidase and PAL in the infested resistant （Ptb 33, TKM6 and LFR831311） and wild rice genotypes （Oryza minuta and O. rhizomatis）. A decrease in leaf protein content was evident invariably in all the infested rice genotypes. It is also evident that the contents of biochemicals such as phenol, ortho- dihydroxy phenol and tannin were negatively correlated with leaffolder damage. However, leaf protein content was positively correlated with the damage by rice leaffolder. SDS-PAGE analysis for total protein profiling of healthy and C. medinalis-infested genotypes revealed the enhanced expression of a high molecular weight （〉 97 kDa） protein in all the genotypes. Besides, there was also an increased induction of a 38 kDa protein in C. medinalis infested resistant genotypes, which was absent in uninfested plants. The present investigation proved that the elevated levels of biochemicals and enzymes may play a vital role in rice plants resistance to RLF.
基金the University Grant Commission, New Delhi, India for providing financial assistance as student fellowship to carry out these studies
文摘Folding and spinning behavior of Cnaphalocrocis medinalis （Guenee） （Lepidoptera： Pyralidae） in different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild rice genotypes were significantly different. Longer leaf selection time and folding time per primary fold; shorter primary fold and whole leaf fold; lower number of binds per primary fold and whole leaf fold were recorded in resistant and wild rice genotypes. In the correlation analysis, it was found that the leaf folding parameters were positively correlated to leaf folder damage whereas the leaf spinning parameters were negatively correlated. Similarly, the morphological characters differed significantly among the chosen genotypes and were related to leaffolder damage. The leaf width and total productive tiller number were positively correlated to leaffolder infestation. Results also indicated that the trichome density and length, leaf length and plant height might contribute to resistance whereas total number of green leaves had no effect on leaffolder infestation. In the scatter plot analysis between leaf folding and spinning characters and leaffolder damage, the genotypes were separated into four groups viz., resistant （TKM6, Ptb 33, LFR831311, Oryza rhizomatis and O. minuta）, moderately resistant （ASD16 and CORH1）, moderately susceptible （ADT36, Pusa Basmati and CB200290） and susceptible （IR36 and TN1）. The present investigation proved that the leaf morphology viz., leaf length and width, plant height and trichome density and length may play a vital role in resistance against rice leaffolder.
基金supported by the 11th 5-year Major Project of National Science and Technology Support Plan(Grant No. 2011BAD16B05)Youth Foundation Project of Sichuan Agricultural University in ChinaOutstanding Master’s Thesis Foundation Project of Sichuan Agricultural University in China
文摘Effects of shading at the flowering and grain filling stages on osmotic regulation substance content and protective enzyme activities in the leaves of different rice genotypes （e.g., Ilyou 498, Gangyou 188, Dexiang 4103, Gangyou 527 and Chuanxiang 9838） were investigated. The results showed that the malondialdehyde content of Gangyou 188 significantly increased under shading, whereas those of Ilyou 498, Dexiang 4103, Gangyou 527 and Chuanxiang 9838 showed no significant differences compared to the control. The soluble sugar content significantly decreased in Ilyou 498, Gangyou 188, Dexiang 4103 and Chuanxiang 9838, whereas it did not significantly increase in Gangyou 527 under the weak light conditions （shading）. Moreover, the soluble protein content in the leaves of different genotypes tended to decrease under shading. Further, the protective enzyme activities in the leaves varied in different rice genotypes under the shading treatment. Based on the osmotic regulation substance content and the protective enzyme activities in the leaves of different rice genotypes, it was concluded that Gangyou 188 and Gangyou 527 had strong abilities to adapt to the low light conditions. In addition, the mechanism of damage to rice leaves in different genotypes under shading was discussed.
基金partly financially supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science(Grant No.20K05762)China Scholarship Council(Grant No.201806990031)。
文摘Ionomic profiles are primarily influenced by genetic and environmental factors.Identifying ionomic responses to varietal effects is necessary to understand the ionomic variations among species or subspecies and to potentially understand genetic effects on ionomic profiles.We cultivated 120 rice(Oryza sativa)varieties to seedling stage in identical hydroponic conditions and determined the concentrations of 26 elements(including 3 anions)in the shoots and roots of rice.Although the subspecies effects were limited by the genus Oryza pre-framework and its elemental chemical properties,we found significant differences in ionomic variations in most elements among the aus,indica and japonica subspecies.Principal component analysis of the correlations indicated that variations in the root-to-shoot ionomic transport mechanisms were the main causes of ionomic differences among the subspecies.Furthermore,the correlations were primarily associated with the screening of varieties for elemental covariation effects that can facilitate breeding biofortified rice varieties with safe concentrations of otherwise toxic elements.The japonica subspecies exhibited the strongest elemental correlations and elemental covariation effects,therefore,they showed greater advantages for biofortification than the indica and aus subspecies,whereas indica and aus subspecies were likely safer in metal(loid)polluted soils.We also found that geographical and historical distribution significantly defined the ionomic profiles.Overall,the results of this study provided a reference for further association studies to improve the nutritional status and minimize toxicity risks in rice production.
文摘To assist with rapid screening for rice blast resistance as a precursor in a breeding program, the susceptibility to rice blast of 13 rice genotypes from Australia was evaluated in May to June 2013 using three distinct inoculation methods（spot, filter paper and standard methods） at seedling, vegetative and reproductive stages. The results revealed that the spot and filter paper inoculation methods were successful in discerning susceptibility to the rice blast disease（P ≤ 0.05）. Disease susceptibility declined significantly from the vegetative to reproductive stages. The standard method was conducted at three different stages for pot plants grown inside the mist house. However, low temperatures did not produce disease symptoms except in a few genotypes. Among the 13 rice genotypes screened, AAT9 expressed a highly resistant response, and AAT4, AAT6, AAT10, AAT11, AAT13, AAT17 and AAT18 expressed resistance at various stages. The results will be useful for selecting elite genotypes for disease tolerance where rice blast is prevalent. In addition, the resistant genotypes can serve as a gene pool used in breeding programmes to develop new resistant genotypes.
文摘Nutrition management is the most important for high yield production but it may affect the response of rice plants to pest and diseases due to the change of microclimate under rice plant canopy. The knowledge of nutrition management and its relation with pest and diseases are basis for setting up a high yield production system. Most of the pest and disease control procedures used by farmers can be considered as soil fertility management and these nutrition practices can have impact on the physiological susceptibility of crop plants to pest and diseases by affecting the plant resistance. Silicon content of plants is particularly effective against pest and diseases in rice and certain rice genotypes are more efficient accumulators of silicon, thus making them more resistant. In the absence of natural heritable resistance in rice varieties, resistance could be induced by altemate strategies to suppress certain pest and pathogens. Hence experiments were carried out in two stages during kharif 2010 and 2011 to assess the concentration of silicon in the index leaves of rice plant utilizing 133 varieties in four locations. The silica content of promising varieties ranged from 1.50% to 3.20%, 1.60% to 3.15%, 1.49% to 3.20% and 1.55% to 3.06% with a mean values of 2.50%, 2.48%, 2.51% and 2.43% at Jagtial, Warangal, Rajendranagar and Rudrur centres of Telangana region and not much variation in mean silica content in index leaves at different places. The overall yield from four locations ranged from 2,653 kg/ha to 6,860 kg/ha with a mean of 5,624 kg/ha. The yields recorded at Jagtial, Warangal, Rajendranagar and Rudrur centres ranged from 2,886 to 7,198, 2,653 to 6,831, 2,653 to 6,860 and 4,399 to 5,950 kg/ha, respectively. The lowest mean yield 5,069 kg/ha was noticed at Rudrur and the highest yield 5,940 kg/ha was found at Warangal. The variations in yields might be due to genotypic variations and also due to variations in climatic conditions of different locations.
文摘The experiment was conducted at the Plant Physiology Laboratory (central laboratory) and Shade house of Field Laboratory of Agricultural Botany Department, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh under a field experiment was also carried out on yield contributing parameters. There were three rice genotypes namely BRRI dhan55 (V<sub>1</sub>), BR6976-2B-15 (V<sub>2</sub>) and tolerant check Hashikalmi (V<sub>3</sub>) and seven water stress were imposed as treatments. The treatments were arranged for 0 days of water stress (control) irrigated continuously throughout the experimental period (T<sub>0</sub>). When the seedlings were 20 days old, water deficit was imposed for seven days (T<sub>1</sub>), when the seedlings were 35 days old, water deficit was imposed for seven days (T<sub>2</sub>), when the seedlings were 55 days old, water deficit was imposed for seven days (T<sub>3</sub>), when the seedlings were 75 days old, water deficit was imposed for seven days (T<sub>4</sub>). When the seedlings were 95 days old, water deficit was imposed for seven days (T<sub>5</sub>) and when the seedlings were 115 days old, water deficit was imposed for seven days (T<sub>6</sub>). BRRI dhan55 and Hashikalmi produced the highest tillers, grains, number of spikelets and yield. The grain sterility percentage is much higher in BR6976-2B-15 due to water stress treatment compared to other genotypes. Grain yield was the highest in BRRI dhan55 and Hashikalmi and gradually decreased with increased water stress treatment compared to other genotypes. Decreased grain yield per plant under water stress treatment reduction of tillers, panicle, filled grains, root, shoot, spikelet/panicle, panicle dry matter content, and with other causes. The harvest index was decreased due to water stress conditions in all the genotypes while less affected in BRRI dhan55 and Hashikalmi.
文摘Insufficient N supply is an important constraint to productivity of lowland rice. Studies on N nutrition of rice cultivars with different durations representing the north western part of Indo-Gangetic Plains are scanty. A field experiment was conducted during kharif seasons of 2006 and 2007 at PAU, Ludhiana to assess the differences in grain yield and N utilization of three popular rice cultivars at varying N doses. Significant differences among genotypes were observed in grain yield, N uptake, N use efficiency and N utilization efficiency. The cultivar PAU-201 was found to be superior among all the tested genotypes. Total N uptake and grain N uptake was highest in cultivar PAU-201 followed by cultivars PR-115 and PR-113. On an average, the response to applied N for grain yield was observed upto 90 kg N ha1. Grain yield increased significantly up to 90 kg N hal in cultivars PR-115 and PAU-201 and up to 120 kg N ha1 in PR-113. Apparent recovery efficiency （ARE） and Partial factor productivity （PFPN） of N was significantly reduced at higher level of N （150 kg N hal）. It was concluded that N uptake is predominant factor in grain yield formation and cultivars differ in NUE suggesting that it may be possible to develop cultivars that are efficient at low nutrient level or are capable of using N more efficiently when applied as fertilizer.
基金supported by the Special Funds for Agroscientific Research (No. 200903015)the Quality Supervision Scientific Research (No. 200910201) in the public interest
文摘Cadmium （Cd） entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type （P 〈 0.01）. The Cd concentration was higher in red paddy soil （RP） than in yellow clayey paddy soil （YP）. The average Cd concentrations of different organs in three rice types were indica 〉 hybrid 〉 japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055--0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard （0.2 mg/kg）. The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly （P 〈 0.01） correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice.
基金This research work was supported by the National Natural Science Foundation of China(30070445)the Natural Science Foundation of Jiangsu Province(BK2001146).
文摘Solution culture experiments were carried out to study the NO3- uptake kinetics by rice roots and the nitrate reductase activity (NRA) in leaves of four typical rice genotypes (conventional indica, conventional japonica, hybrid indica, and hybrid japonica) at different growth stages. The effects of NH4+ on the NO3- uptake kinetics was also studied. The results indicated that the four genotypes responded differently to NO3- and NH4+. Comparing indica rice with japonica rice, hybrid rice with conventional rice, formers absorbed NO3-more rapidly than laters. The superiority of indica rice and hybid rice for NO3- uptake was mainly due to the higher Vmax at the early growth stage (20 days) and the higher affinity of nitrate transporters for NO3- at the middle growth stage (50 days). At both growth stages NH4+ significantly inhibited NO3- uptake for japonica rice, but showed little effect for indica rice. Conversely, NH4+ stimulated the uptake of NO3- for hybrid rice. NH4+ could repress NRA in leaves of all four genotypes with a sensitive order as following: hybrid japonica > hybrid indica > conventional indica > conventional japonica.
基金Project supported by the Harvest Plus-China Program (No. HPC-8234)the Key International Cooperative Project (No. 2006DFA31030)the Department of Education of Zhejiang Province (No. N20100339)
文摘Zinc(Zn) is an essential micronutrient for humans,but Zn deficiency has become serious as equally as iron(Fe) and vitamin A deficiencies nowadays.Selection and breeding of high Zn-density crops is a suitable,cost-effective,and sustainable way to improve human health.However,the mechanism of high Zn density in rice grain is not fully understood,especially how Zn transports from soil to grains.Hydroponics experiments were carried out to compare Zn uptake and distribution in two different Zn-density rice genotypes using stable isotope technique.At seedling stage,IR68144 showed higher 68Zn uptake and transport rate to the shoot for the short-term,but no signifi-cant difference was observed in both genotypes for the long-term.Zn in xylem sap of IR68144 was consistently higher,and IR68144 exhibited higher Zn absorption ratio than IR64 at sufficient(2.0 μmol/L) or surplus(8.0 μmol/L) Zn supply level.IR64 and IR68144 showed similar patterns of 68Zn accumulation in new leaves at seedling stage and in de-veloping grains at ripening stage,whereas 68Zn in new leaves and grains of IR68144 was consistently higher.These results suggested that a rapid root-to-shoot translocation and enhanced xylem loading capacity may be the crucial processes for high Zn density in rice grains.
基金supported by the Program of Introducing Talents of Discipline to University in China (Grant No.B08025)
文摘Genetic analysis of rolled leaf is important to rice ideotype breeding. To detect loci controlling rolled leaf of japonica restorer lines, SSR marker genotypes and phenotypes of flag leaf rolling index （LRI） were investigated in Xiushui 79 （P1, a japonica rice variety）, C Bao （P2, a japonica restorer line） and 254 recombinant inbred lines derived from the cross between P1 and P2 , and in two environments. A genetic map of this cross was constructed, QTLs for LRI were detected and their interactions with environments were analyzed. Among 818 pairs of SSR primers, 90 primers showed polymorphism between P1 and P2, and 12 markers showed highly significant correlation with LRI in both environments based on single marker regression analysis. The genetic map containing 74 information loci has a total distance of 744.6 cM, with an average of 10.1 cM between two adjacent loci. Three QTLs （qRL-1, qRL-7 and qRL-8-1） were detected with two softwares： WinQTLCart 2.5 and QTLNetwork2.0. qRL-8-1 was a new locus, accounting for 15.5% and 12.8% of phenotypic variations in the two environments, respectively. The phenotypic variation explained by additive effect was 6.6%. No interaction was found between qRL-8-1 genotype and environments.
文摘Zinc deficiency is one of the most widespreadmicro-nutritional disorder for rice. To solve the problem, screening Zn-efficient cultivars isan available method and understanding geno-
文摘Chalkiness is an unpleasant trait for rice con-sumer,which is known to be controlled geneti-cally and affected by environment during grainmaturing.We used the model of Additive Main
文摘Diversity array technology （DART^TM） was a genotyping tool characterized gel-independent and high throughput. The main purpose of present study is to validate DArT for rice （Oryza sativa L.）genotyping in a high throughput manner. Technically, the main objective was to generate a rice general purpose gene pool, and optimize this genomic tool in order to evaluate rice germplasm genetic diversity. To achieve this, firstly, a generalpurpose DArT array was developed. Ten representatives from 24 varieties were hybridized with the general-purpose array to determine the informativeness of the clones printed on the array. The informative 1 152 clones were re-arrayed on a slide and used to fingerprint 17 of 24 germplasms. Hybridizing targets prepared from the germplasm to be assayed to the DNA array gave DNA fingerprints of germplasms. Raw data were normalized and transformed into binary data, which were then analyzed by using NTSYSpc （Numerical taxonomy system for cluster and ordination analysis, v. 2.02j） software package. The graphically displayed dendrogram derived from the array experimental data was matched with simple sequence repeats genotyping outline and varieties＇ pedigree deviation of the different varieties. Considering DArT is a sequence-independent genotyping approach, it will be applied in studies of the genetic diversity and the gene mapping of diverse of organisms, especially for those crops with less-developed molecular markers.
基金National Basic Research Program of China(2014CB954500)National Natural Science Foundation of China(31261140364,31370457).
文摘Background:Increasing atmospheric[CO_(2)]can increase photosynthesis and promote plant growth,consequently influencing nitrogen(N)cycling.Yet,there is no systematic information on the N response among different organs of japonica and indica rice genotypes to elevated[CO_(2)]as affected by N application.To investigate the impacts of elevated[CO_(2)]and N fertilization on N uptake and utilization of different genotypic rice(Oryza sativa L.)during grain filling,a free-air CO_(2) enrichment(FACE)experiment with indica cv.Liangyou 084(IIY084)and japonica cv.Wuyunjing 23(WYJ23)was conducted in Eastern China.Crops were exposed to ambient[CO_(2)]and elevated[CO_(2)](200μmol mol^(−1) above ambient)at two levels of N:control(0N)and 22.5 g N m^(−2)(normal N,NN),and they were sampled at 82 days after transplanting(DAT),99 DAT,and maturity,respectively.Results:Under FACE,significant declines of N concentration in all tissues and the whole plants were observed with the greater decrease in leaves and stems at three stages.Positive responses of N use efficiency(NUE)to elevated[CO_(2)]were recorded over the study period.The total N accumulation remained unchanged,while a large amount of N was partitioned to panicles at the expense of leaves and stems.As compared to WYJ23,greater N transportation from roots to aboveground,especially the panicles,was observed on IIY084 accompanied by higher panicle biomass(82 DAT and 99 DAT),N concentrations(maturity),and greater NUE for leaves through the study season.Across all[CO_(2)]and cultivars,N fertilization increased N partitioning to leaves and stems while decreasing that to panicles.Additionally,N supply decreased NUE while stimulating N concentrations and N amounts of rice plants.Among all treatments,IIY084 had the highest N accumulation and allocation in panicles under elevated[CO_(2)]in combination with N fertilizer at maturity.Conclusion:Data from this study were helpful for understanding the temporal N uptake and utilization of different rice genotypes as affected by N availability and suggest that IIY084 promises a considerable prospect for its grain yield and quality under future elevated atmospheric[CO_(2)].
