The effects of different arsenic (As) treatments on spatial pattern of radial oxygen loss (ROL), iron (Fe) plaque formation and As accumulation in rice were investigated using three rice genotypes, planted under...The effects of different arsenic (As) treatments on spatial pattern of radial oxygen loss (ROL), iron (Fe) plaque formation and As accumulation in rice were investigated using three rice genotypes, planted under greenhouse conditions. Arsenic was applied to soil at 50 and 100 mg/kg, with untreated soil used as a control having an average As concentration of 8.5 mg/kg. It was demonstrated that the ratio of ROL in root tips to that at the root base slightly decreased with increasing As concentration, suggesting that the spatial ROL patterns in these groups may be shifted from the “tight” barrier towards the “partial” barrier form. Furthermore, increasing As concentration led to a increase in Fe plaque formation on root surfaces. In addition, root As concentrations of genotypes in 50 and 100 mg/kg As treatments were significantly higher than that of control treatment (P〈0.05). Grain As concentration of genotype Nanyangzhan (with lower ROL) was significantly higher (P〈0.05) than that of genotype CNT87059-3 with higher ROL.展开更多
Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots and affects uptake and translocation of certain nutrients. In the present study, rice plants were cultured in Fe-deficient or sufficie...Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots and affects uptake and translocation of certain nutrients. In the present study, rice plants were cultured in Fe-deficient or sufficient solutions and placed in a medium containing selenium (Se) for 2 h. Then, FeSO4 was added at the various concentrations of 0, 10, 40, or 70 mg L-1 to induce varying levels of iron plaque on the root surfaces and subsequent uptake of Se was monitored. The uptake of Se was inhibited by the iron plaque, with the effect proportional to the amount of plaque induced. The activity of cysteine synthase was decreased with increasing amounts of iron plaque on the roots. This may be the important reason for iron plaque inhibition of Se translocation. At each level of iron plaque, Fe-deficient rice had more Se than Fe-sufficient rice. Furthermore, with plaque induced by 20 mg Fe L-1, plants from Fe-deficient media accumulated more Se than those from Fe-sufficient media, as the Se concentration was increased from 10 to 30 or 50 mg L^-1. We found that phytosiderophores, highly effective iron chelating agents, could desorb selenite from ferrihydrite. Root exudates of the Fe-deficient rice, especially phytosiderophores in the exudates, could enhance Se uptake by rice plants with iron plaque.展开更多
Global efforts to address malnutrition and hidden hunger, particularly prevalent in low- and middle-income countries, have intensified, with a focus on enhancing the nutritional content of staple crops like rice. Desp...Global efforts to address malnutrition and hidden hunger, particularly prevalent in low- and middle-income countries, have intensified, with a focus on enhancing the nutritional content of staple crops like rice. Despite serving as a staple for over half of the world's population, rice falls short in meeting daily nutritional requirements, especially for iron(Fe) and zinc(Zn). Genetic resources, such as wild rice species and specific rice varieties, offer promising avenues for enhancing Fe and Zn content. Additionally, molecular breeding approaches have identified key genes and loci associated with Fe and Zn accumulation in rice grains. This review explores the genetic resources and molecular mechanisms underlying Fe and Zn accumulation in rice grains. The functional genomics involved in Fe uptake, transport, and distribution in rice plants have revealed key genes such as OsFRO1, OsIRT1, and OsNAS3. Similarly, genes associated with Zn uptake and translocation, including OsZIP11 and OsNRAMP1, have been identified. Transgenic approaches, leveraging transporter gene families and genome editing technologies, offer promising avenues for enhancing Fe and Zn content in rice grains. Moreover, strategies for reducing phytic acid(PA) content, a known inhibitor of mineral bioavailability, have been explored, including the identification of low-PA mutants and natural variants. The integration of genomic information, including whole-genome resequencing and pan-genome analyses, provides valuable insights into the genetic basis of micronutrient traits and facilitates targeted breeding efforts. Functional genomics studies have elucidated the molecular mechanisms underlying Fe uptake and translocation in rice. Furthermore, transgenic and genome editing techniques have shown promise in enhancing Fe and Zn content in rice grains through the manipulation of key transporter genes. Overall, the integration of multi-omics approaches holds significant promise for addressing global malnutrition and hidden hunger by enhancing the nutritional quality of rice, thereby contributing to improved food and nutritional security worldwide.展开更多
In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silic...In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silicon limits its adoption by farmers. A study was carried out in Zakogbeu;Center-West of Côte d’Ivoire, to assess the potential of kaolin to mitigate the effect of this soil constraint on the root of the rice plant. Five kaolin-based treatments were analyzed (T<sub>0 </sub>= 0 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>1</sub> = 366 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>2</sub> = 736 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>3</sub> = 1097 kg kaolin ha<sup>−</sup><sup>1</sup> and T<sub>4</sub> = 1465 kg kaolin ha<sup>−</sup><sup>1</sup> are 0, 200, 400, 600 and 800 kg SiO<sub>2</sub> ha<sup>−</sup><sup>1</sup>) in a device in complete random blocks, with 5 repetitions. The results obtained show that kaolin supply increases the length of the root tissue as well as the number of branching of the root of the rice plant. Root tissue increased from 10 cm with T<sub>0</sub> treatment to more than 15 cm with treatment T<sub>4</sub>. The microscopic observation of the roots shows that in the treatment T<sub>0</sub>, the roots present only primary ramifications and the tertiary and quaternary ramifications are observed with the treatments T<sub>3</sub> and T<sub>4</sub>. The contribution of kaolin is an alternative to inhibit the effect of iron toxicity on the rice plant root development in iron toxicity condition.展开更多
In this study, through vitro culturing anthers of 7 F1 progenies of early Japonica rice in cold region on medium with different Fe2+ contents, it was found that Fe2+ content generated greater impacts on the induction ...In this study, through vitro culturing anthers of 7 F1 progenies of early Japonica rice in cold region on medium with different Fe2+ contents, it was found that Fe2+ content generated greater impacts on the induction rate and green plantlet differentiation. The result demonstrated that if Fe2+ increased from 32 to 40 mg/kg, the induction rate of early Japonica rice anther culture in N6 culture media was more then 1.4 times higher than that in N6 culture media containing 5.6 mg/kg Fe2+. In this concentration range, the induction rate increased with the increase of Fe2+ content, while if the concentration was over this concentration range, the induction rate decreased with the increase of Fe2+, showing single peak distribution. When the Fe2+ was 40 mg/kg in differentiation medium, the differentiation rate decreased dramatically. The green plantlet differentiations of callus which were induced on culture media containing 32-40 mg/kg Fe2+ were different, when they were cultured on MS culture media, and 85.7% materials could increase green plantlet productivity to about 7.8%. Therefore, increasing Fe2+in induction media properly could increase anther culture efficiency of early Japonica rice in cold region.展开更多
A total of 105 transgenic dce lines independently transformed with a pea ferritin gene (Fer) were previously obtained. After seven generations of selfing and β-glucuronidase (GUS) assisted selection, 82 transgeni...A total of 105 transgenic dce lines independently transformed with a pea ferritin gene (Fer) were previously obtained. After seven generations of selfing and β-glucuronidase (GUS) assisted selection, 82 transgenic lines with stable agronomic traits were got. Among the 82 transgenic lines, two high-iron transgenic rice lines Fer34 and Fer65, with the iron contents in the milled rice being 4.82 and 3.46 times of that of the wild type Xiushui 11, respectively were identified. In the two transgenic lines, the exogenous Fer gene was highly expressed, and inherited as a single locus. The transgene had no negative effect on the agronomic traits of rice plant, other mineral nutritional components, appearance quality and eating quality of the milled rice, indicating that these two lines were elite high-iron breeding lines. Furthermore, the practical application and further studies facilitating utilization of the two elite breeding lines were discussed.展开更多
Iron-modified biochar(FeOS)is known to be effective at immobilization of arsenic(As)in soils.A pot experiment was conducted to investigate the effects of FeOS on As availability and ttransportation in the soil-rice sy...Iron-modified biochar(FeOS)is known to be effective at immobilization of arsenic(As)in soils.A pot experiment was conducted to investigate the effects of FeOS on As availability and ttransportation in the soil-rice system at different growth stages of rice with different pollution levels.The results showed that Fe concentration decreased and As concentration increased in paddy soils with the FeOS addition,especially in 120 mg/kg As treatment,the As concentration decreased by 16.46%and 30.56%at the maturity stage with 0.5%and 1%FeOS additions,respectively.Compared with the control,the application of FeOS reduced the arsenic content in rice tissues and increased the biomass,with the root biomass increased by 12.68%and the shoot biomass was increased by 8.94%with the addition of 1%FeOS.This may be related to the promotion of iron plaque formation and the transformation of microbial community structure in FeOS treatments,in accordance with the result of gene abundance and Fe/As contents of iron plaque in the study.This study is expected to provide further support and theoretical basis for the application of FeOS in the remediation of As contaminated paddy soil.展开更多
To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border c...To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2+ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2+ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2+. Increased Fe^2+ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2+ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2+ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2+ treatment; The viability of border cells decreased by 10% when the Fe^2+ concentration increased by 100 mg/L. After 24 h Fe^2+ treatment, the viabilities of border cells at all the Fe^2+ levels were 〈65%; The viability of border cells decreased by 20% when the Fee+ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2+ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.展开更多
Although available iron is usually abundant for the growth of rice cultivated in waterlogged condition, the rice crop may suffer from its deficiency when cultivated in aerobic soil since the soil properties are totall...Although available iron is usually abundant for the growth of rice cultivated in waterlogged condition, the rice crop may suffer from its deficiency when cultivated in aerobic soil since the soil properties are totally different from waterlogged. Solubility of iron is very low in soils with high Eh and/or high pH. A field experiment with five different depth (10, 20, 30, 40 and 50 cm) of groundwater, and a pot experiment with five treatments of ammonium nitrate ratio (100/0, 75/25, 50/50, 25/75 and 0/100) were conducted to study the characteristics of iron nutrition of rice in non full irrigation condition. Moreover, the contents of iron extracted by 1 mol L 1 HCl of rice plant samples of 8 cultivars from both aerobic and waterlogged cultivation were analyzed to study the effect of water regimes on iron content of rice plants. The results were as follows: (1) The average content of available Fe (2.70 mg kg 1 ) of 5 layers of the soil treated with 10 cm depth of groundwater was significantly higher than that (0.83 mg kg 1 ) with 50 cm depth of groundwater, and the iron concentration of rice plant of the former was much higher than that of the later. (2) Iron deficiency of rice became much severe when high ratio of nitrate (more than 75 percent) in nitrogen fertilizer applied at different intervals in aerobic cultivation. (3) The iron concentrations of 3 cultivars, Wuyujing3 (99 mg kg 1 ), Yangdao4 (87 mg kg 1 ) and 9520 (95 mg kg 1 ), of rice plants cultivated in aerobic condition were significantly less than those(195, 197 and 175 mg kg 1 ) respectively in waterlogged condition at tillering stage. And even much significant differences existed in the iron concentrations of different cultivars growing in the aerobic and waterlogged condition at maturity.展开更多
Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not b...Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.展开更多
Iron and zinc are two trace elements that are essential for rice. But they are toxic at higher concentrations, leading to severe rice yield losses especially in acid soils and inland valleys. In this study, two recipr...Iron and zinc are two trace elements that are essential for rice. But they are toxic at higher concentrations, leading to severe rice yield losses especially in acid soils and inland valleys. In this study, two reciprocal introgression line(IL) populations sharing the same parents were used with high-density SNP bin markers to identify QTL tolerant to iron and zinc toxicities. The results indicated that the japonica variety 02,428 had stronger tolerance to iron and zinc toxicities than the indica variety Minghui 63. Nine and ten QTL contributing to iron and zinc toxicity tolerances,respectively, were identified in the two IL populations. The favorable alleles of most QTL came from 02,428. Among them, q FRRDW2, q ZRRDW3, and q FRSDW11 appeared to be independent of genetic background. The region C11S49–C11S60 on chromosome 11 harbored QTL affecting multiple iron and zinc toxicity tolerance-related traits, indicating partial genetic overlap between the two toxicity tolerances. Our results provide essential information and materials for developing excellent rice cultivars with iron and/or zinc tolerance by marker-assisted selection(MAS).展开更多
Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the pro...Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the production of aerobic rice. Short- term hydroponic culture experiments were conducted to study the response of aerobic rice to Fe deficiency and the effect of root exudates from Fe-deficient wheat on its Fe uptake ability. The results indicate that the amount of phytosiderophores (PS) released from aerobic rice did not increase under Fe deficient conditions. The Fe(III) reducing capacity of Fe-deficient aerobic rice did not increase and the solution pH did not decrease significantly. What's more, no obvious swelling was observed in the root tips. Aerobic rice did not show special responses to improve their Fe nutrition under Fe deficiency as both strategy I and II plants though they were very sensitive to Fe deficiency. This may be a reason which causes Fe deficiency problem in aerobic rice. However, root exudates from Fe-deficient wheat (PSw) could improve its Fe nutrition in the presence of insoluble Fe(OH)3. This suggests that aerobic rice could utilize Fe activated by PSw.展开更多
Effect of Fe nutrition on Fe acquisition, aconitase enzyme activity and assimilation of the element in ferritin protein was studied in two indica rice cultivars viz. Sharbati and Lalat having contrasting grain Fe conc...Effect of Fe nutrition on Fe acquisition, aconitase enzyme activity and assimilation of the element in ferritin protein was studied in two indica rice cultivars viz. Sharbati and Lalat having contrasting grain Fe concentration. Young rice seedlings were grown in hydroponics with different levels of Fe. For comparison, the two cultivars were also grown in the field under natural conditions of rice culture. Iron accumulation, aconitase activity and ferritin level were higher in the high Fe containing cultivar, Sharbati than that in the low Fe containing cultivar, Lalat. While aconitase activity increased consistently with the increase in concentration of Fe in the growing medium, the same was not found to be true for accumulation of ferritin protein. The leaf ferritin level increased up to a certain level of Fe in the growing medium and declined thereafter. Levels of Fe in the growing medium giving maximum ferritin synthesis were found to be different in the two rice cultivars. In both cultivars, aconitase activity attained maximum level after 20 days of panicle emergence (heading). Pattern of Fe accumulation in the leaves in response to increasing Fe level in the nutrient solution paralleled with that of the aconitase activity indicating a positive correlation. It was concluded that accumulation of both ferritin protein and aconitase enzyme were influenced not only by the Fe level in the growing medium but also by the internal Fe concentration of the two cultivars.展开更多
The adsorption of aluminium(III) and iron(III) ions from their single and binary systems, by RHAC was investigated in a batch system. The activated carbon prepared from rice hulls was characterized by scanning electro...The adsorption of aluminium(III) and iron(III) ions from their single and binary systems, by RHAC was investigated in a batch system. The activated carbon prepared from rice hulls was characterized by scanning electron microscopy and Fourier transformation infrared techniques. Batch adsorption experiments were performed under different operating conditions including pH (2 - 5), adsorbent dosage (0.5 - 2.0 g/l), initial ion concentration (5 - 100 mg/l), and contact time (30 - 240 min). The equilibrium time for maximum ions removal was found to be 180 min in single and binary ions systems. The kinetics of adsorption was evaluated using the pseudo-first order, pseudo-second order and Elovich kinetic models. The Langmuir, Freundlich and Temkin equilibrium models were applied to the adsorption experimental data. Real wastewater samples were collected from different locations to investigate the efficiency of rice hull activated carbon in treating real samples. The real wastewater samples were treated with the activated carbon prepared from rice hulls and a commercial activated carbon. The results showed that the activated carbon prepared in the present work was more efficient in the removal of aluminium and iron from real wastewater as compared to the commercial activated carbon which is more advantageous considering both economics and environmental parameters.展开更多
With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expr...With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expression under high Fe and low phosphorus(P) conditions,and sequence polymorphism.Genotypes Sahbhagi Dhan,Chakhao Poirieton and Shasharang were high yielders with no bronzing symptom visible under Fe toxic field conditions,and BAM350 and BAM811 were low yielders but did not show bronzing symptoms.Hydroponic screening revealed that the number of crown roots and root length can be traits for consideration for identifying Fe toxicity tolerance in rice genotypes.Fe contents in rice roots and shoots of a high-yielding genotype KMR3 showing leaf bronzing were significantly high.In response to 24 h high Fe stress,the expression levels of OsNAS3 were up-regulated in all genotypes except KMR3.In response to 48 h high Fe stress,the expression levels of OsNAS1 were3-fold higher in tolerant Shasharang,whereas in KMR3,it was significantly down-regulated.Even in response to 7 d excess Fe stress,the transcript abundances of OsIRO2 and OsNAS3 were contrasting in genotypes Shasharang and KMR3.This suggested that the reported Fe deficiency genes had a role in Fe toxicity and that in genotype KMR3 under excess Fe stress,there was disruption of metal homeostasis.Under the 48 h low P conditions,OsIRO2 and OsYSL16 were significantly up-regulated in Fe tolerant genotype Shasharang and in low P tolerant genotype Chakhao Poirieton,respectively.In silico sequence analysis across 3 024 rice genotypes revealed polymorphism for 4 genes.Sequencing across OsIRO3and OsNAS3 revealed nucleotide polymorphism between tolerant and susceptible genotypes for Fe toxicity.Non-synonymous single nucleotide polymorphisms and insertion/deletions(InDels) differing in tolerant and susceptible genotypes were identified.A marker targeting 25-bp InDel in OsIRO3,when run on a diverse panel of 43 rice genotypes and a biparental population,was associated with superior performance for yield under acidic lowland field conditions.This study highlights the potential of one of the vital genes involved in Fe homeostasis as a genic target for improving rice yield in acidic soils.展开更多
To investigate the effect of nitrogen (N) level on iron (Fe) content in milled rice, a field experiment was carried out under three N application levels including 0, 150 and 300 kg/hm2 by using 120 rice genotypes....To investigate the effect of nitrogen (N) level on iron (Fe) content in milled rice, a field experiment was carried out under three N application levels including 0, 150 and 300 kg/hm2 by using 120 rice genotypes. In addition to the genotypic differences of iron content in milled rice, grain yield, 1000-grain weight and N content in grains under the same N level, there were also variations in the response of Fe content in milled rice to N levels. Based on the range and variation coefficient of Fe content in milled rice under the three N levels, the response of Fe content in milled rice to N levels could be classified into four types including highly insensitive, insensitive, sensitive and highly sensitive types. A significant quadratic correlation was found between the Fe content in milled rice and 1000-grain weight or the N content in grains. However, no significant correlation between the Fe content in milled rice and grain yield was detected. In conclusion, there are genotypic differences in the effects of N levels on Fe content in milled rice, which is favorable to breeding of Fe-rich rice under different N environments. Furthermore, high yield and Fe-rich rice could be grown through the regulation of nitrogen on Fe content in milled rice, 1000-grain weight and N content in milled rice.展开更多
Soil salinity seriously affects the utilization of farmland and threatens the crop production.Here,a selenium-nitrogen-co-doped carbon dots was developed,which increased rice seedling growth and alleviated its inhibit...Soil salinity seriously affects the utilization of farmland and threatens the crop production.Here,a selenium-nitrogen-co-doped carbon dots was developed,which increased rice seedling growth and alleviated its inhibition by salt stress by foliar spraying.The treatment activated Ca^(2+)and jasmonic acid signaling pathways and increased iron homeostasis,antioxidant defense,and cell wall development of rice seedlings.It could be used to increase crop resistance to environmental stress.展开更多
A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe ̄(32) PO_4 . nH_2O, tagging directly the iron...A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe ̄(32) PO_4 . nH_2O, tagging directly the ironphophate in calcareous paddy soils.Results showed that under waterlogged condition, similar to iron phosphate in acidic paddy soils, that incalcareous paddy soils was an important source of phosphorus to rice plant, and the amount of phosphorusoriginated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.展开更多
Iron toxicity,a physiological disorder of rice,is widelyspread in tropical and subtropical areas and causes severerice yield reduction.Although there has been a consider-able amount of research on flee growth,nutrient...Iron toxicity,a physiological disorder of rice,is widelyspread in tropical and subtropical areas and causes severerice yield reduction.Although there has been a consider-able amount of research on flee growth,nutrient uptaking,展开更多
With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savan...With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.展开更多
基金Projects(41201493,31300815)supported by the National Natural Science Foundation of China
文摘The effects of different arsenic (As) treatments on spatial pattern of radial oxygen loss (ROL), iron (Fe) plaque formation and As accumulation in rice were investigated using three rice genotypes, planted under greenhouse conditions. Arsenic was applied to soil at 50 and 100 mg/kg, with untreated soil used as a control having an average As concentration of 8.5 mg/kg. It was demonstrated that the ratio of ROL in root tips to that at the root base slightly decreased with increasing As concentration, suggesting that the spatial ROL patterns in these groups may be shifted from the “tight” barrier towards the “partial” barrier form. Furthermore, increasing As concentration led to a increase in Fe plaque formation on root surfaces. In addition, root As concentrations of genotypes in 50 and 100 mg/kg As treatments were significantly higher than that of control treatment (P〈0.05). Grain As concentration of genotype Nanyangzhan (with lower ROL) was significantly higher (P〈0.05) than that of genotype CNT87059-3 with higher ROL.
基金Project supported by the National Key Technologies Research and Development Program of China during the 10th Five-Year Plan Period (No.2002AA601012).
文摘Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots and affects uptake and translocation of certain nutrients. In the present study, rice plants were cultured in Fe-deficient or sufficient solutions and placed in a medium containing selenium (Se) for 2 h. Then, FeSO4 was added at the various concentrations of 0, 10, 40, or 70 mg L-1 to induce varying levels of iron plaque on the root surfaces and subsequent uptake of Se was monitored. The uptake of Se was inhibited by the iron plaque, with the effect proportional to the amount of plaque induced. The activity of cysteine synthase was decreased with increasing amounts of iron plaque on the roots. This may be the important reason for iron plaque inhibition of Se translocation. At each level of iron plaque, Fe-deficient rice had more Se than Fe-sufficient rice. Furthermore, with plaque induced by 20 mg Fe L-1, plants from Fe-deficient media accumulated more Se than those from Fe-sufficient media, as the Se concentration was increased from 10 to 30 or 50 mg L^-1. We found that phytosiderophores, highly effective iron chelating agents, could desorb selenite from ferrihydrite. Root exudates of the Fe-deficient rice, especially phytosiderophores in the exudates, could enhance Se uptake by rice plants with iron plaque.
文摘Global efforts to address malnutrition and hidden hunger, particularly prevalent in low- and middle-income countries, have intensified, with a focus on enhancing the nutritional content of staple crops like rice. Despite serving as a staple for over half of the world's population, rice falls short in meeting daily nutritional requirements, especially for iron(Fe) and zinc(Zn). Genetic resources, such as wild rice species and specific rice varieties, offer promising avenues for enhancing Fe and Zn content. Additionally, molecular breeding approaches have identified key genes and loci associated with Fe and Zn accumulation in rice grains. This review explores the genetic resources and molecular mechanisms underlying Fe and Zn accumulation in rice grains. The functional genomics involved in Fe uptake, transport, and distribution in rice plants have revealed key genes such as OsFRO1, OsIRT1, and OsNAS3. Similarly, genes associated with Zn uptake and translocation, including OsZIP11 and OsNRAMP1, have been identified. Transgenic approaches, leveraging transporter gene families and genome editing technologies, offer promising avenues for enhancing Fe and Zn content in rice grains. Moreover, strategies for reducing phytic acid(PA) content, a known inhibitor of mineral bioavailability, have been explored, including the identification of low-PA mutants and natural variants. The integration of genomic information, including whole-genome resequencing and pan-genome analyses, provides valuable insights into the genetic basis of micronutrient traits and facilitates targeted breeding efforts. Functional genomics studies have elucidated the molecular mechanisms underlying Fe uptake and translocation in rice. Furthermore, transgenic and genome editing techniques have shown promise in enhancing Fe and Zn content in rice grains through the manipulation of key transporter genes. Overall, the integration of multi-omics approaches holds significant promise for addressing global malnutrition and hidden hunger by enhancing the nutritional quality of rice, thereby contributing to improved food and nutritional security worldwide.
文摘In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silicon limits its adoption by farmers. A study was carried out in Zakogbeu;Center-West of Côte d’Ivoire, to assess the potential of kaolin to mitigate the effect of this soil constraint on the root of the rice plant. Five kaolin-based treatments were analyzed (T<sub>0 </sub>= 0 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>1</sub> = 366 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>2</sub> = 736 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>3</sub> = 1097 kg kaolin ha<sup>−</sup><sup>1</sup> and T<sub>4</sub> = 1465 kg kaolin ha<sup>−</sup><sup>1</sup> are 0, 200, 400, 600 and 800 kg SiO<sub>2</sub> ha<sup>−</sup><sup>1</sup>) in a device in complete random blocks, with 5 repetitions. The results obtained show that kaolin supply increases the length of the root tissue as well as the number of branching of the root of the rice plant. Root tissue increased from 10 cm with T<sub>0</sub> treatment to more than 15 cm with treatment T<sub>4</sub>. The microscopic observation of the roots shows that in the treatment T<sub>0</sub>, the roots present only primary ramifications and the tertiary and quaternary ramifications are observed with the treatments T<sub>3</sub> and T<sub>4</sub>. The contribution of kaolin is an alternative to inhibit the effect of iron toxicity on the rice plant root development in iron toxicity condition.
基金Supported by National Key Technology R&D Program(2006BAD01A01-6)~~
文摘In this study, through vitro culturing anthers of 7 F1 progenies of early Japonica rice in cold region on medium with different Fe2+ contents, it was found that Fe2+ content generated greater impacts on the induction rate and green plantlet differentiation. The result demonstrated that if Fe2+ increased from 32 to 40 mg/kg, the induction rate of early Japonica rice anther culture in N6 culture media was more then 1.4 times higher than that in N6 culture media containing 5.6 mg/kg Fe2+. In this concentration range, the induction rate increased with the increase of Fe2+ content, while if the concentration was over this concentration range, the induction rate decreased with the increase of Fe2+, showing single peak distribution. When the Fe2+ was 40 mg/kg in differentiation medium, the differentiation rate decreased dramatically. The green plantlet differentiations of callus which were induced on culture media containing 32-40 mg/kg Fe2+ were different, when they were cultured on MS culture media, and 85.7% materials could increase green plantlet productivity to about 7.8%. Therefore, increasing Fe2+in induction media properly could increase anther culture efficiency of early Japonica rice in cold region.
文摘A total of 105 transgenic dce lines independently transformed with a pea ferritin gene (Fer) were previously obtained. After seven generations of selfing and β-glucuronidase (GUS) assisted selection, 82 transgenic lines with stable agronomic traits were got. Among the 82 transgenic lines, two high-iron transgenic rice lines Fer34 and Fer65, with the iron contents in the milled rice being 4.82 and 3.46 times of that of the wild type Xiushui 11, respectively were identified. In the two transgenic lines, the exogenous Fer gene was highly expressed, and inherited as a single locus. The transgene had no negative effect on the agronomic traits of rice plant, other mineral nutritional components, appearance quality and eating quality of the milled rice, indicating that these two lines were elite high-iron breeding lines. Furthermore, the practical application and further studies facilitating utilization of the two elite breeding lines were discussed.
基金Project(2019YFC1803601)supported by the National Key Research and Development Program of ChinaProject(41771512)supported by the National Natural Science Foundation of ChinaProject(2018RS3004)supported by Hunan Science&Technology Innovation Program,China。
文摘Iron-modified biochar(FeOS)is known to be effective at immobilization of arsenic(As)in soils.A pot experiment was conducted to investigate the effects of FeOS on As availability and ttransportation in the soil-rice system at different growth stages of rice with different pollution levels.The results showed that Fe concentration decreased and As concentration increased in paddy soils with the FeOS addition,especially in 120 mg/kg As treatment,the As concentration decreased by 16.46%and 30.56%at the maturity stage with 0.5%and 1%FeOS additions,respectively.Compared with the control,the application of FeOS reduced the arsenic content in rice tissues and increased the biomass,with the root biomass increased by 12.68%and the shoot biomass was increased by 8.94%with the addition of 1%FeOS.This may be related to the promotion of iron plaque formation and the transformation of microbial community structure in FeOS treatments,in accordance with the result of gene abundance and Fe/As contents of iron plaque in the study.This study is expected to provide further support and theoretical basis for the application of FeOS in the remediation of As contaminated paddy soil.
基金Project (Nos. Y307535 and Y304185) supported by the Natural Science Foundation of Zhejiang Province,China
文摘To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2+ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2+ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2+. Increased Fe^2+ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2+ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2+ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2+ treatment; The viability of border cells decreased by 10% when the Fe^2+ concentration increased by 100 mg/L. After 24 h Fe^2+ treatment, the viabilities of border cells at all the Fe^2+ levels were 〈65%; The viability of border cells decreased by 20% when the Fee+ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2+ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.
文摘Although available iron is usually abundant for the growth of rice cultivated in waterlogged condition, the rice crop may suffer from its deficiency when cultivated in aerobic soil since the soil properties are totally different from waterlogged. Solubility of iron is very low in soils with high Eh and/or high pH. A field experiment with five different depth (10, 20, 30, 40 and 50 cm) of groundwater, and a pot experiment with five treatments of ammonium nitrate ratio (100/0, 75/25, 50/50, 25/75 and 0/100) were conducted to study the characteristics of iron nutrition of rice in non full irrigation condition. Moreover, the contents of iron extracted by 1 mol L 1 HCl of rice plant samples of 8 cultivars from both aerobic and waterlogged cultivation were analyzed to study the effect of water regimes on iron content of rice plants. The results were as follows: (1) The average content of available Fe (2.70 mg kg 1 ) of 5 layers of the soil treated with 10 cm depth of groundwater was significantly higher than that (0.83 mg kg 1 ) with 50 cm depth of groundwater, and the iron concentration of rice plant of the former was much higher than that of the later. (2) Iron deficiency of rice became much severe when high ratio of nitrate (more than 75 percent) in nitrogen fertilizer applied at different intervals in aerobic cultivation. (3) The iron concentrations of 3 cultivars, Wuyujing3 (99 mg kg 1 ), Yangdao4 (87 mg kg 1 ) and 9520 (95 mg kg 1 ), of rice plants cultivated in aerobic condition were significantly less than those(195, 197 and 175 mg kg 1 ) respectively in waterlogged condition at tillering stage. And even much significant differences existed in the iron concentrations of different cultivars growing in the aerobic and waterlogged condition at maturity.
文摘Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.
基金funded by the National High Technology Research and Development Program of China (No. 2014AA10A601)Hubei Collaborative Innovation Center for Grain Industry (No.LXT-16-01) to JLX+2 种基金the Shenzhen Peacock Plan (No.20130415095710361) to ZKLthe CAAS Innovative Team Award to JLX's teamKey Discipline of Crop Science of Yangtze University to HL
文摘Iron and zinc are two trace elements that are essential for rice. But they are toxic at higher concentrations, leading to severe rice yield losses especially in acid soils and inland valleys. In this study, two reciprocal introgression line(IL) populations sharing the same parents were used with high-density SNP bin markers to identify QTL tolerant to iron and zinc toxicities. The results indicated that the japonica variety 02,428 had stronger tolerance to iron and zinc toxicities than the indica variety Minghui 63. Nine and ten QTL contributing to iron and zinc toxicity tolerances,respectively, were identified in the two IL populations. The favorable alleles of most QTL came from 02,428. Among them, q FRRDW2, q ZRRDW3, and q FRSDW11 appeared to be independent of genetic background. The region C11S49–C11S60 on chromosome 11 harbored QTL affecting multiple iron and zinc toxicity tolerance-related traits, indicating partial genetic overlap between the two toxicity tolerances. Our results provide essential information and materials for developing excellent rice cultivars with iron and/or zinc tolerance by marker-assisted selection(MAS).
基金supported by National Basic Research Program of China (973 Program, 2009CB118605)the National Natural Science Foundation of China (30571106)the Innovative Group Grant of Natural Science Foundation of China (30821003)
文摘Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the production of aerobic rice. Short- term hydroponic culture experiments were conducted to study the response of aerobic rice to Fe deficiency and the effect of root exudates from Fe-deficient wheat on its Fe uptake ability. The results indicate that the amount of phytosiderophores (PS) released from aerobic rice did not increase under Fe deficient conditions. The Fe(III) reducing capacity of Fe-deficient aerobic rice did not increase and the solution pH did not decrease significantly. What's more, no obvious swelling was observed in the root tips. Aerobic rice did not show special responses to improve their Fe nutrition under Fe deficiency as both strategy I and II plants though they were very sensitive to Fe deficiency. This may be a reason which causes Fe deficiency problem in aerobic rice. However, root exudates from Fe-deficient wheat (PSw) could improve its Fe nutrition in the presence of insoluble Fe(OH)3. This suggests that aerobic rice could utilize Fe activated by PSw.
文摘Effect of Fe nutrition on Fe acquisition, aconitase enzyme activity and assimilation of the element in ferritin protein was studied in two indica rice cultivars viz. Sharbati and Lalat having contrasting grain Fe concentration. Young rice seedlings were grown in hydroponics with different levels of Fe. For comparison, the two cultivars were also grown in the field under natural conditions of rice culture. Iron accumulation, aconitase activity and ferritin level were higher in the high Fe containing cultivar, Sharbati than that in the low Fe containing cultivar, Lalat. While aconitase activity increased consistently with the increase in concentration of Fe in the growing medium, the same was not found to be true for accumulation of ferritin protein. The leaf ferritin level increased up to a certain level of Fe in the growing medium and declined thereafter. Levels of Fe in the growing medium giving maximum ferritin synthesis were found to be different in the two rice cultivars. In both cultivars, aconitase activity attained maximum level after 20 days of panicle emergence (heading). Pattern of Fe accumulation in the leaves in response to increasing Fe level in the nutrient solution paralleled with that of the aconitase activity indicating a positive correlation. It was concluded that accumulation of both ferritin protein and aconitase enzyme were influenced not only by the Fe level in the growing medium but also by the internal Fe concentration of the two cultivars.
文摘The adsorption of aluminium(III) and iron(III) ions from their single and binary systems, by RHAC was investigated in a batch system. The activated carbon prepared from rice hulls was characterized by scanning electron microscopy and Fourier transformation infrared techniques. Batch adsorption experiments were performed under different operating conditions including pH (2 - 5), adsorbent dosage (0.5 - 2.0 g/l), initial ion concentration (5 - 100 mg/l), and contact time (30 - 240 min). The equilibrium time for maximum ions removal was found to be 180 min in single and binary ions systems. The kinetics of adsorption was evaluated using the pseudo-first order, pseudo-second order and Elovich kinetic models. The Langmuir, Freundlich and Temkin equilibrium models were applied to the adsorption experimental data. Real wastewater samples were collected from different locations to investigate the efficiency of rice hull activated carbon in treating real samples. The real wastewater samples were treated with the activated carbon prepared from rice hulls and a commercial activated carbon. The results showed that the activated carbon prepared in the present work was more efficient in the removal of aluminium and iron from real wastewater as compared to the commercial activated carbon which is more advantageous considering both economics and environmental parameters.
基金supported by the grants from Indian Council of Agricultural Research (Grant No. C30033/415101-036)Department of Biotechnology,Government of India (Grant No. BT/566/NE/U-excel/2016/72)+1 种基金supported by Rajiv Gandhi National FellowshipNational Fellowship for Higher Education of ST Students (Grant No. 201516-NFST-2015-17-ST-3514), respectively, from the Ministry of Tribal Affairs, University Grant Commission, Government of India。
文摘With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expression under high Fe and low phosphorus(P) conditions,and sequence polymorphism.Genotypes Sahbhagi Dhan,Chakhao Poirieton and Shasharang were high yielders with no bronzing symptom visible under Fe toxic field conditions,and BAM350 and BAM811 were low yielders but did not show bronzing symptoms.Hydroponic screening revealed that the number of crown roots and root length can be traits for consideration for identifying Fe toxicity tolerance in rice genotypes.Fe contents in rice roots and shoots of a high-yielding genotype KMR3 showing leaf bronzing were significantly high.In response to 24 h high Fe stress,the expression levels of OsNAS3 were up-regulated in all genotypes except KMR3.In response to 48 h high Fe stress,the expression levels of OsNAS1 were3-fold higher in tolerant Shasharang,whereas in KMR3,it was significantly down-regulated.Even in response to 7 d excess Fe stress,the transcript abundances of OsIRO2 and OsNAS3 were contrasting in genotypes Shasharang and KMR3.This suggested that the reported Fe deficiency genes had a role in Fe toxicity and that in genotype KMR3 under excess Fe stress,there was disruption of metal homeostasis.Under the 48 h low P conditions,OsIRO2 and OsYSL16 were significantly up-regulated in Fe tolerant genotype Shasharang and in low P tolerant genotype Chakhao Poirieton,respectively.In silico sequence analysis across 3 024 rice genotypes revealed polymorphism for 4 genes.Sequencing across OsIRO3and OsNAS3 revealed nucleotide polymorphism between tolerant and susceptible genotypes for Fe toxicity.Non-synonymous single nucleotide polymorphisms and insertion/deletions(InDels) differing in tolerant and susceptible genotypes were identified.A marker targeting 25-bp InDel in OsIRO3,when run on a diverse panel of 43 rice genotypes and a biparental population,was associated with superior performance for yield under acidic lowland field conditions.This study highlights the potential of one of the vital genes involved in Fe homeostasis as a genic target for improving rice yield in acidic soils.
基金supported by the Key Projects in the National Science & Technology Pillar Program of China (Grant No. 2006BAD02A03)the National Natural Science Foundation of China (Grant Nos. 30971732 and 30671223)
文摘To investigate the effect of nitrogen (N) level on iron (Fe) content in milled rice, a field experiment was carried out under three N application levels including 0, 150 and 300 kg/hm2 by using 120 rice genotypes. In addition to the genotypic differences of iron content in milled rice, grain yield, 1000-grain weight and N content in grains under the same N level, there were also variations in the response of Fe content in milled rice to N levels. Based on the range and variation coefficient of Fe content in milled rice under the three N levels, the response of Fe content in milled rice to N levels could be classified into four types including highly insensitive, insensitive, sensitive and highly sensitive types. A significant quadratic correlation was found between the Fe content in milled rice and 1000-grain weight or the N content in grains. However, no significant correlation between the Fe content in milled rice and grain yield was detected. In conclusion, there are genotypic differences in the effects of N levels on Fe content in milled rice, which is favorable to breeding of Fe-rich rice under different N environments. Furthermore, high yield and Fe-rich rice could be grown through the regulation of nitrogen on Fe content in milled rice, 1000-grain weight and N content in milled rice.
基金financially supported by the National Natural Science Foundation of China (42207032,52070064)the Key Project of National Natural Science Foundation of China (42330705)+2 种基金Key R&D Project of Hebei Province (21373601D)Advanced Talents Incubation Program of the Hebei University (521100222012)economic support from Collaborative Innovation Center for Baiyangdian Basin Ecological Protection and Beijing-Tianjin-Hebei Sustainable Development and Institute of Life Sciences and Green Development of Hebei University。
文摘Soil salinity seriously affects the utilization of farmland and threatens the crop production.Here,a selenium-nitrogen-co-doped carbon dots was developed,which increased rice seedling growth and alleviated its inhibition by salt stress by foliar spraying.The treatment activated Ca^(2+)and jasmonic acid signaling pathways and increased iron homeostasis,antioxidant defense,and cell wall development of rice seedlings.It could be used to increase crop resistance to environmental stress.
文摘A study was carried out on contribution of iron pbosphate to phosphorus nutrition of rice plant nnderwaterlogged and moist conditions, respectively, by use of synthetic Fe ̄(32) PO_4 . nH_2O, tagging directly the ironphophate in calcareous paddy soils.Results showed that under waterlogged condition, similar to iron phosphate in acidic paddy soils, that incalcareous paddy soils was an important source of phosphorus to rice plant, and the amount of phosphorusoriginated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.
文摘Iron toxicity,a physiological disorder of rice,is widelyspread in tropical and subtropical areas and causes severerice yield reduction.Although there has been a consider-able amount of research on flee growth,nutrient uptaking,
文摘With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.