Application Of Rice Research Articles

Experimental and numerical study of wheat and rice doughs

Physicochemical, morphological, rheological characteristics and finite element modelling of wheat flour, rice flour, starch and gluten were studied in this work. The physicochemical analysis of rice flour exhibited almost similar characteristics to wheat flour without gluten present. Rice flour and rice starch contained higher value of carbohydrate and fibres compared to wheat flour and wheat starch. Likewise, rice flour and rice starch interacted strongly with water and oil due to higher value of water absorption, water solubility and oil absorption indices compared to wheat flour and wheat starch. SEM images showed that rice starch had uniform size, smaller polyhedral shape and were closely intact between granules, whereas wheat starch consisted of large and small granules that were sphere and irregular in shapes. Compression tests conducted on all the doughs showed viscoelastic behaviour and permanent set. Stress-strain curve of rice starch-gluten dough are shown to be higher than wheat starch-gluten dough. Oscillation tests conducted on all doughs showed larger storage than loss modulus, indicating more elastic than viscous behaviour of the doughs. Finally, finite element model using ‘chess’ geometry for starch and gluten was able to simulate deformation of starch-gluten dough. • Application of rice in food production for intolerant gluten consumer. • Rice flour contains higher value of carbohydrate and fibre compared to wheat flour. • Physicochemical, morphological, rheological and element modelling were studied. • Finite element model; ‘chess’ model to simulate deformation of starch-gluten dough.

Protocol for ethyl methanesulphonate (EMS) mutagenesis application in rice

Background: Non-transgenic chemical mutagen application, particularly ethyl methanesulfonate (EMS), is an important tool to create mutations and gain a new genetic makeup for plants. It is useful to obtain a sufficient number of mutant plants instead of working with a severe mutation in a few plants. EMS dose and exposure period have been previously studied in several crops; however, EMS used to create point mutations in presoaked rice seeds has not been sufficiently studied and there is no standard protocol for such treatment. The aim of this study is to establish a standard protocol for EMS mutagenesis application in rice. Methods: Two studies were conducted to evaluate the effect of four durations of rice seed presoaking (0, 6, 12, and 24 hours), four EMS concentration doses (0.0%, 0.5%, 1.0%, and 2.0%), and four EMS exposure periods (6, 12, 24, and 48 hours). Germination rate, plumula and radicle length, seedling survival, LD50 (Lethal Dose) determination, shoot length, root length and fresh seedling weight were evaluated. Results: Results showed that a 12-hour presoaking duration, 0.5% EMS dose, and six hours of EMS exposure were the best practices for the optimum number of mutant plants. Conclusions: In light of both this study and the literature, a standard application protocol was established. This application protocol, detailed in this article, contains the following guidelines: (1) Presoaking: 12 hours, (2) EMS application: 0.5% dose EMS and six hours, (3) Final washing: six hours, (4) Drying: 72 hours at 38°C. A user-friendly protocol has been presented for utilization by researchers.

Genomic insight into balancing high yield, good quality, and blast resistance of japonica rice

BackgroundBalancing the yield, quality and resistance to disease is a daunting challenge in crop breeding due to the negative relationship among these traits. Large-scale genomic landscape analysis of germplasm resources is considered to be an efficient approach to dissect the genetic basis of the complex traits. Central China is one of the main regions where the japonica rice is produced. However, dozens of high-yield rice varieties in this region still exist with low quality or susceptibility to blast disease, severely limiting their application in rice production.ResultsHere, we re-sequence 200 japonica rice varieties grown in central China over the past 30 years and analyze the genetic structure of these cultivars using 2.4 million polymorphic SNP markers. Genome-wide association mapping and selection scans indicate that strong selection for high-yield and taste quality associated with low-amylose content may have led to the loss of resistance to the rice blast fungus Magnaporthe oryzae. By extensive bioinformatic analyses of yield components, resistance to rice blast, and taste quality, we identify several superior alleles for these traits in the population. Based on this information, we successfully introduce excellent taste quality and blast-resistant alleles into the background of two high-yield cultivars and develop two elite lines, XY99 and JXY1, with excellent taste, high yield, and broad-spectrum of blast resistance.ConclusionsThis is the first large-scale genomic landscape analysis of japonica rice varieties grown in central China and we demonstrate a balancing of multiple agronomic traits by genomic-based strategy.

Contribution of Selected Factors on Farmers’ Work Performance towards Fertilizer Application in Rice of Bangladesh

There is enormous possibility to increase rice yield in Bangladesh. Inefficient and often imbalanced fertilizer use impedes farmers from achieving expected yields. It is evident from past research that farmers have resorted to applying fertilizers at inappropriate rates that do not match well with the nutrient requirement of certain crops. Therefore, this study explores the contribution of selected factors that influence farmers’ work performance and determine the highest contributing factors on farmers’ work performance towards fertilizer application in rice. This research used a multistage simple random sampling method to select 355 farmers from twenty-one rice production areas of Bangladesh. Data, collected using a structured questionnaire, were subjected to multiple linear regression analysis to explore the contribution of selected factors and identify the highest contributing factors towards farmers’ work performance. Results revealed that all the factors explained 56.1% of the variance in farmers’ work performance. Motivation of farmers was found to be the highest contributing factor, followed by knowledge that influences farmers’ work performance. The study concludes that farmers need to be equipped with essential knowledge and motivation crucial to strengthening their work performance as this will subsequently increase rice production.

Glucan, Water-Dikinase 1 (GWD1), an ideal biotechnological target for potential improving yield and quality in rice.

SummaryThe source–sink relationship determines the overall agronomic performance of rice. Cloning and characterizing key genes involved in the regulation of source and sink dynamics is imperative for improving rice yield. However, few source genes with potential application in rice have been identified. Glucan, Water‐Dikinase 1 (GWD1) is an essential enzyme that plays a pivotal role in the first step of transitory starch degradation in source tissues. In the present study, we successfully generated gwd1 weak mutants by promoter editing using CRISPR/Cas9 system, and also leaf‐dominant overexpression lines of GWD1 driven by Osl2 promoter. Analysis of the gwd1 plants indicated that promoter editing mediated down‐regulation of GWD1 caused no observable effects on rice growth and development, but only mildly modified its grain transparency and seed germination. However, the transgenic pOsl2::GWD1 overexpression lines showed improvements in multiple key traits, including rice yield, grain shape, rice quality, seed germination and stress tolerance. Therefore, our study shows that GWD1 is not only involved in transitory starch degradation in source tissues, but also plays key roles in the seeds, which is a sink tissue. In conclusion, we find that GWD1 is an ideal biotechnological target with promising potential for the breeding of elite rice cultivars via genetic engineering.

Scenario of Plant Breeding in Nepal and Its Application in Rice

Rice, the number one staple food crop of Nepal, contributes nearly 20% to the agricultural gross domestic product, almost 7% to gross domestic product, and supplies with 40% of the food calorie consumption of Nepalese people. Despite of increasing production, the national demand of rice cannot be fulfilled, and billions of rupees are spent yearly for importing rice from India. This article reviews history, recent scenario, prospects, and importance of rice breeding research in Nepal for self-sufficiency. Though plant breeding inception point in Nepal was 1951, the systematic research in rice was started from 1972 after the establishment of the National Rice Research Program. Introduction and evaluation of high yielding exotic germplasm of rice was the initial rice breeding activities. After analysing several foreign materials, CH-45 variety of rice was first recommended in 1959. Nepal Agriculture Research Council (NARC), the leading organisation for rice varietal improvement to date, has been doing rice research activities such as germplasm conservation, exchange, varietal development, verification of technologies, and knowledge updates in collaboration with various organizations. International Rice Research Institute (IRRI), since 1966, has been playing an important role in Nepal’s rice research. Major plant breeding achievements are introduction of exotic materials and their evaluation, local landraces identification, collection and analysis, crossing of local landraces with exotic genetic materials, heterosis breeding, tissue culture technology, genetic marker technology, and National Genebank. RAPD and SSR, DNA-based markers, are mostly used for diversity appraisal and selecting desirable genotypes. Integration of advanced tools such as genetic engineering, bioinformatics, protoplast fusion, and SNP markers could not be still applied in rice research and development. Hence, emphasis should be given to improve the capacity and abilities of the rice scientists and should release more short duration, drought, and submergence-tolerant rice varieties by optimum utilisation of local landraces combining modern and conventional breeding.

GENETIC BASIS OF RICE AROMA GENE AND ITS APPLICATION IN RICE GENETICS AND BREEDING: A REVIEW

GENETIC BASIS OF RICE AROMA GENE AND ITS APPLICATION IN RICE GENETICS AND BREEDING: A REVIEW

Protocol for ethyl methanesulphonate (EMS) mutagenesis application in rice

Background: Non-transgenic chemical mutagen application, particularly ethyl methanesulfonate (EMS), is an important tool to create mutations and gain a new genetic makeup for plants. It is useful to obtain a sufficient number of mutant plants instead of working with a severe mutation in a few plants. EMS dose and exposure period have been previously studied in several crops; however, EMS used to create point mutations in presoaked rice seeds has not been sufficiently studied and there is no standard protocol for such treatment. The aim of this study is to establish a standard protocol for EMS mutagenesis application in rice. Methods: Two studies were conducted to evaluate the effect of four durations of rice seed presoaking (0, 6, 12, and 24 hours), four EMS concentration doses (0.0%, 0.5%, 1.0%, and 2.0%), and four EMS exposure periods (6, 12, 24, and 48 hours). Germination rate, plumula and radicle length, seedling survival, shoot length, root length and fresh seedling weight were evaluated. Results: Results showed that a 12-hour presoaking duration, 0.5% EMS dose, and six hours of EMS exposure were the best practices for the optimum number of mutant plants. Conclusions: In light of both this study and the literature, a standard application protocol was established. This application protocol, detailed in this article, contains the following guidelines: (1) Presoaking: 12 hours, (2) EMS application: 0.5% dose EMS and six hours, (3) Final washing: six hours, (4) Drying: 72 hours at 38°C. A user-friendly protocol has been presented for utilization by researchers.

Real-time nitrogen management using decision support-tools increases nitrogen use efficiency of rice

Several decision support tools have been proposed for precision nitrogen (N) fertilizer application in rice (Oryza sativa L.) to increase nitrogen use efficiency (NUE) and grain yields. However, a comparison of their effectiveness has not been well documented. A field experiment was conducted in western Terai of Nepal during 2017–2018 to identify the appropriate decision support tool for improving NUE and grain yields. Nine N fertilizer management treatments were laid out in a randomized complete block design with three replications. The treatments included a GreenSeeker (GS) optical sensor, soil plant analysis development (SPAD) meter, leaf color chart (LCC), each of these treatments with basal application of N at 25 kg ha−1, urea briquette deep placement (UDP), and the existing government-recommended practice (RP, 100 kg N ha−1). N fertilizer application guided by decision support tools had a significant (p < 0.05) effect on grain yields. UDP produced the highest grain yield (6.80 Mg ha−1) among the treatments. Grain yields were not significantly different among GS, LCC (in combination with basal 25 kg N ha−1), RP, and UDP treatments. However, GS, UDP, and LCC saved N input by 54%, 22%, and 21%, respectively, compared to RP. In addition, GS produced a significantly higher agronomic N use efficiency (ANUE), partial factor productivity of N (PFPN), apparent N recovery (ANR), and utilization efficiency of N (UEN) compared to RP. These results suggest that application of N fertilizer guided by the GS decision support tool can save significant amount of N fertilizer compared to the current RP without compromising grain yield.

Evaluating verification awareness as a method for assessing adaptation risk

Self-integration requires a system to be self-aware and self-protecting of its functionality and communication processes to mitigate interference in accomplishing its goals. Incorporating self-protection into a framework for reasoning about compliance with critical requirements is a major challenge when the system’s operational environment may have uncertainties resulting in runtime changes. The reasoning should be over a range of impacts and tradeoffs in order for the system to immediately address an issue, even if only partially or imperfectly. Assuming that critical requirements can be formally specified and embedded as part of system self-awareness, runtime verification often involves extensive on-board resources and state explosion, with minimal explanation of results. Model-checking partially mitigates runtime verification issues by abstracting the system operations and architecture. However, validating the consistency of a model given a runtime change is generally performed external to the system and translated back to the operational environment, which can be inefficient.This paper focuses on codifying and embedding verification awareness into a system. Verification awareness is a type of self-awareness related to reasoning about compliance with critical properties at runtime when a system adaptation is needed. The premise is that an adaptation that interferes with a design-time proof process for requirement compliance increases the risk that the original proof process cannot be reused. The greater the risk to limiting proof process reuse, the higher the probability that the requirement would be violated by the adaptation. The application of Rice’s 1953 theorem to this domain indicates that determining whether a given adaptation inherently inhibits proof reuse is undecidable, suggesting the heuristic, comparative approach based on proof metadata that is part of our approach. To demonstrate our deployment of verification awareness, we predefine four adaptations that are all available to three distinct wearable simulations (hearables, stress, and insulin delivery). We capture metadata from applying automated theorem proving to wearable requirements and assess the risk among the four adaptations for limiting the proof process reuse for each of their requirements. The results show that the adaptations affect proof process reuse differently on each wearable. We evaluate our reasoning framework by embedding checkpoints for requirement compliance within the wearable code and log the execution trace of each adaptation. The logs confirm that the adaptation selected by each wearable with the lowest risk of inhibiting proof process reuse for its requirements also causes the least number of requirement failures in execution.

Protocol for ethyl methanesulphonate (EMS) mutagenesis application in rice

Protocol for ethyl methanesulphonate (EMS) mutagenesis application in rice

Elucidation of induced host plant resistance to white backed plant hopper (WBPH) in response to zinc application in rice

Aim: The experiment was aimed to study the effects of various Zn formulations towards induced host plant resistance to WBPH in rice. Methodology: Eight zinc treatments comprising basal and foliar applications(at 30 and 45 DAT) of Zn SO4 and Zn-EDTA and their combinations were tested for induced host plant resistance to WBPH (a dreadful sucking insect) in a most sensitive rice variety TN 1. In addition, a treatment without any Zn application served as control. The pot grown plants were kept in the Mylar cages with top end covered by fine mesh muslin cloth and as such maintained till maturity. One adult gravid female insect was released into each cage (at 46DAT) and the insect population build-up was recorded after one month. Soluble protein profiling of leaf samples (at 60DAT) of each treatment was done by SDS-PAGE and data were analyzed for clustering pattern. Results: Altogether, 19 polypeptide bands (14.3-97.4kDa) were revealed. The low molecular weight proteins (14.3-25.1 kDa) were clearly absent in the control. T6(Zn EDTA at basal and foliar) recorded least WBPH build–up and elicited highest number (15) of polypeptide bands including five new bands at 66.0, 37.0, 23.6, 15.8 and 14.3 kDa. Further, 66.0kDa, 37.0 kDa and 14.3 kDa polypeptide bands were commonly shared by T6, T7(ZnSO4 basal+ EDTA foliar) and T8(Zn EDTA basal + ZnSO4) that recorded lower WBPH population and grouped together as compared to rest of the treatments and control. However, 23.6 kDa polypeptide band induced only in T6 and T7 seems to have greater role in manifestation of induced defence mechanism against WBPH in rice. Interpretation: The differentially expressed proteins (as compared to control) revealed in response to Zn application may be considered as biochemical basis of induced resistance for the pest in rice Key words: Induced resistance, Soluble protein profiling, White backed plant hopper, Zinc

Effect of Mineral N on C and N Dynamics of Rice and Wheat Residues under Different Moisture Levels

Crop residue mineralization affects soil carbon (C) and nitrogen (N) dynamics during crop residue management in crop production. C and N mineralization dynamics of rice and wheat residues incorporated with and without mineral N under two moisture conditions were evaluated under laboratory conditions. Mineral N was applied @ 0.015 g/Kg (»30 Kg/ha), whereas soil moisture was maintained at high (» – 15 KPa, near field capacity) and at low (» – 500 KPa)moisture levels during course of study.Periodic determinations on CO2 – C and N mineralized were performed over a period of 120 days. The highest peaks for CO2 – C occurred during first week of the study which then reduced gradually until it attained an equilibrium. High moisture level enhanced CO2 – C flux by 14% than low moisture level. Combined application of crop residues and mineral N released 17% more CO2 – C than crop residue treatments without mineral N.In residue applied treatments, immobilization was 40% higher at high moisture level than that at low moisture level. Application of rice and wheat residues in combination with mineral N caused both immobilizations followed by mineralization phases at both moisture levels. At high moisture level, maximum immobilization occurred during initial 15 days, while at low moisture level it continued till about 30 days. After day15, mineralization started which continued to increase during remaining period of study at high moisture and at low moisture mineralization initiated from day 60 onward. Mineralization in rice residue was faster than that in wheat residues. Immobilization of N continued progressively in residue alone treated soils at both moisture levels during study period. In residue treated soils, increase in soil moisture increased soil organic carbon (SOC) and soil water stable aggregates (WSA) significantly by 14% and 55% over control respectively.Combined application of crop residues and mineral N increased SOC by 43% and WSA by 59%. This study indicated that incorporation of crop residues along with addition of mineral N in the presence of optimum moisture promoted its faster decomposition with a quicker mineral N release, more organic matter build up and soil structure improvement than crop residues incorporated without mineral N.

INTEGRATED PEST MANAGEMENT (IPM) AND ITS APPLICATION IN RICE – A REVIEW

Rice is the staple food crop for more than half of the world’s population though it’s cultivation is done in only 11% of the world’s cultivable land. Several pests attack rice in different ways at different stages. Increased reliance on pesticides for pest control is found to be unsustainable and cost-ineffective. So, Integrated Pest Management (IPM) has been introduced as the best alternative for pest management in rice. IPM in rice helps to minimize risks to the environment and human health. Rice IPM uses the combination of cultural, use of resistant varieties, biological, physical, and chemical practices for pest control. Farmers Field School has been the most effective way to increase IPM knowledge among rice farmers. Such training helps to facilitate the farmers to apply ecologically informed farming practices. There are several challenges regarding the implementation of rice IPM. To increase IPM implementation in rice emphasis should be given on farmers’ training and education. The role of government is also vital for the successful implementation of IPM. This review article provides an overview of various IPM practices being performed in rice fields at present.

Life cycle environmental impact assessment of rice-crayfish integrated system: A case study

Rice-crayfish integrated system (RCIS) as a sustainable agricultural system has been widely and rapidly promoted in China. However, the environmental impact potential of RCIS is still unknown compared with conventional rice monoculture system (RM). A life cycle assessment (LCA) methodology was applied to characterize the environmental performance and potential improvement opportunities related to RM and RCIS, and a questionnaire survey of 300 farmers was carried out in Qianjiang city, China. Seven environmental impact categories, including non-renewable energy depletion (NED), global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), human toxicity potential (HTP), freshwater toxicity potential (FTP) and soil toxicity potential (STP) were involved. Results showed that the NED and GWP were primary caused in off-farm stage, but the other environmental impact categories, including AP, EP, HTP, FTP, and STP were mainly occurred in the on-farm stage whether in RM or RCIS. Despite decreased chemical fertilizers and pesticides application in rice growing subsystem, the NED, GWP, AP, EP, HTP and STP were increased in RCIS by 84.30%, 89.37%, 61.88%, 95.87%, 98.06% and 70.78%, respectively, compared with RM. The crayfish farming subsystem produced more resources consumption, pollutant emissions and toxicity potential, with feed production and input being the primarily contributor to environmental impact categories in RCIS. The total environmental impact index from RCIS was 90.95% higher than that from RM. It is worth noting that obviously higher EP was produced in crayfish farming subsystem of RCIS, indicating that pollutant emissions resulted from aquaculture farming might be ignored and hidden in paddy fields. Based on these results, it is suggested that improving aquatic feed utilization, providing necessary technical training and guidance to farmers, and formulating environmental pollution risk control policies and punitive measures might be taken into consideration to ensure the effective use and sustainable development of rice-aquatic animal integrated system.

Evaluasi Mutu Beras dengan Kesesuaian Good Handling Practices dan Good Manufacturing Practices di Kabupaten Bogor

Milled rice is one of the most important agricultural commodities for Indonesian people as staple food. Consumers tend to not know how to differentiate good or low quality of rice. Rice mill (RMU) in Bogor Regency mostly do not have quality standard comply with Indonesian National Standard (SNI). The purpose of this study was to identify the quality of rice and milled rice produced by RMU in Bogor Regency and evaluate the suitability of the application of rice and milled rice handling in RMU to Good Handling Practices (GHP) and Good Manufacturing Practices (GMP). The parameters measured were analysis of rice and milled rice quality and data analysis. The data resulted from measuring the quality of grain and rice was obtained from interview and observation. The results showed that four RMU rice samples not included in the class category SNI 6128: 2015 and two samples included in Medium III (M-3). On the postharvest handling conformity level was 44.92 percent for GHP and 60.25 percent for GMP. GHP and GMP guidelines were not yet fully applied by rice milling unit (RMU).

Direct and residual effect of boron on growth parameters and yield of rice-wheat grown under the Inceptisol of Varanasi

A pot experiment was conducted in net house of the Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India during kharif 2017 and rabi 2017-18 to evaluate the direct effect boron (B) fertilizers on plant growth parameters of rice and their residual effect on subsequent wheat crop grown in B deficient soil (0.42 mg kg-1). The experiment comprised of 9 B levels i.e., 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 kg B ha-1 in soil as borax (B:11%) along with basal dose of nitrogen, phosphorus and potassium as treatments in a completely randomized design (CRD) with three replications. The result showed that among the levels of boron the direct application of 1.5 kg B ha-1 soil along with RDF to rice was most beneficial and brought highest improvement in growth parameters and on succeeding wheat crop the most beneficial and highest yield was in residual B of 3.0 kg B ha-1. The yield increased due to residual effect of B was statistically lower than the direct effect of B. Boron concentration in soils ranged from 0.54 to 0.43 mg kg-1 in rice and 0.29 to 1.25 mg kg-1 in wheat. The plant growth attributes like plant height, Greenness index, and number of tillers along with yield were increased by the direct and residual effect of B levels. The application of boron did not increase grain yield of rice and wheat significantly over RDF. However, application of B @ 2 kg ha-1 or higher doses significantly decreased the rice grain yield. In, wheat, the grain yield was at par in all the treatments. A significant residual effect of B application in rice was noticed even after the harvest of wheat crop particularly at highest doses of application.

Utilization of Rice Husk ash and Bamboo Leaf for Increasing Si for Rice Production on Paddy Soil

Silicate is an important nutrient element for rice plants. Rice is a plant that absorbs Si in large quantities. The low Si content in paddy fields is caused by intensive rice cultivation practices. Ash husk rice and bamboo leaves are materials that have a high silicate content so that the addition of husk ash and bamboo leaves can increase the availability of Si in nature. This research used Randomized Complete Block Design (RCBD), the factor that was tested were Factor I (source of Si : S1, S2) and Factor II (Dosage: D0, D1, D2, D3, D4). The results showed there is significant difference on the available Si, Si uptakeorganic matter, total number tiller, weight of 1000 grains. The application of Rice ask hush dose 10 Mg ha-1 (S1D4) can increase available Si, Uptake Si, Organic Matter, total number tiller and weight of 1000 grains than the appliacation of bamboo leaf.

Application of rice (Oryza sativa L.) root endophytic diazotrophic Azotobacter sp. strain Avi2 (MCC 3432) can increase rice yield under green house and field condition

Use of plant-associated beneficial microbes, especially endophytes are getting popular day by day as they occupy a relatively privileged niche inside different plant tissues with lesser competition for food and shelter than rhizosphere. The effects of different physical factors like temperature, rainfall, and seasonal variation and UV radiation on plant growth promoting endophytic communities are less pronounced than those on the rhizospheric and phylloplane microbes. This present work has been compromised with further utilization of an indigenous rice (Oryza sativa L.) root endophytic Azotobacter sp. strain Avi2 (MCC 3432) (AzA) as a bio-formulation for sustainable rice production based on several physiological parameters (plant height, root length/weight, leaf area, yield, chlorophyll contain), in-vitro comparative plant growth promoting assays, greenhouse and field experiments (dry and wet season). Treatments with AzA exhibited higher yield as well as maximal chlorophyll fluorescence (Fm) of flag leaves in flowering and grain filling stages indicating higher photosynthetic rates. Scanning electron microscopic image of rice roots demonstrated accumulation of bacterial biofilm at the junction of primary and lateral root confirming the root-colonizing ability of the bacterium. The results of the study were quite encouraging as AzA exhibited better vegetative and reproductive growth of rice in pot and field experiment compared to formulated rhizospheric Azotobacter sp. (commercial product). Apart from that plants treated with AzA (supplemented 50% nitrogenous fertilizer of recommended dose) exhibited similar yield parameters when it was compared with the recommended dose of fertilizer (RDF; 120:60:60 mg N:P:K kg−1 soil/ without any bacterial). Therefore, it can be concluded that application of this plant growth promoting endophyte can reduce a substantial amount of N-fertilizer for field application.

Establishment of arsenic speciation analysis method and application in rice

Objective: A new ion exchange column technology was used to establish an efficient and sensitive method for the detection of inorganic arsenic. Methods: Based on the new As Specia Fast Column, the pretreatment methods, liquid phase separation and mass spectrometry determination conditions of inorganic arsenic in rice were optimized. Finally, arsenic compounds were separated by As Specia Fast Column and detected by liquid chromatography inductively coupled plasma mass spectrometry. The external standard method was used for quantitative analysis. The detection limit, precision and accuracy of the method were determined by measuring the content of arsenic compounds in rice samples and rice standard samples. At the same time, three Guangdong rice samples were selected as the experimental samples of this study, and 1 g of each sample was weighed and measured in parallel three times. The method was compared with the method of liquid chromatography-atomic fluorescence spectrometry (LC-AFS) and liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) in the national standard. Results: The inorganic arsenic in rice was extracted with 0.5% nitric acid solution at 65 ℃ for 15 h, and the pH was adjusted to alkaline. The mobile phase A (8 mmol/L HNO(3), 50 mmol/L NH(3)·H(2)O) and mobile phase B (40 mmol/L HNO(3), 80 mmol/L NH(3)·H(2)O) were used as the mobile phase gradient elution (93%) . Five arsenic compounds can reach baseline separation under the conditions of RF power of 1 500 W and atomization gas flow of 0.97 L/min. The detection limits ranged from 0.114 to 0.331 μg/L, and the inorganic arsenic content in rice samples ranged from 0.063 to 0.232 mg/kg. The results of determination of arsenic compounds in rice flour reference materials were all within the uncertainty range indicated by the standard. The recoveries were 86.7%~106.7%, and the precision was 1.9%-12.5%. Compared with national standards, the results of determination of arsenate in rice were relatively close (using this method, LC-AFS, LC-ICP-MS to detect the content of arsenate in rice samples 1 was 0.231, 0.226, 0.236 mg/kg, respectively). However, due to insufficient sensitivity, the national standard method is difficult to detect low levels of arsenic compounds (Arsenobetaine was not detected in rice sample 1). The method can detect the content of arsenobetaine in rice sample 1 was 0.023 mg/kg. Conclusion: The established method can meet the requirements of inorganic arsenic determination in rice, and it is more rapid and accurate than the current national standard. It can better monitor and evaluate the content of i-As in rice, and provide accurate data for comprehensively grasping and evaluating the safety of rice consumption of residents.