Abstract:Carotenoids and anthocyanins are antioxidant metabolites,which play an important role in the resistance of plants to photooxidative stress and contribute to the color of leaves,flowers,and fruits at the same time. The rich color metabolites of fruits are beneficial to human health. This article summarizes the effects of light signals on the biosynthetic metabolic pathways of plant carotenoids and anthocyanins,focusing on the regulatory mechanisms of important transcription factors involved in the light signal pathways of genes for synthesizing carotenoid and anthocyanin,and clarifies a significant role for light signals and photoreceptors in mediating the regulation of carotenoids and anthocyanins biosynthesis. Using sweet orange (Citrus sinensis) as an example,the light response elements of carotenoid and anthocyanin biosynthetic genes were analyzed. The major transcription factors including HY5(elongated hypocotyl 5),BBXs(BBOX containing proteins),COP1(constitutively photomorphogenic 1),PIFs(phytochromeinteracting factors),and HY5BBXs complexes,HY5PIFs complexes，HY5PIFsBBXs complexes,HY5COP1BBXs complexes that participate in these pathways are summarized. It provides an insight into the regulatory mechanism underlying of HY5,BBXs,COP1,PIFsmediated carotenoids and anthocyanins accumulation. Understanding the crucial role of the transcription regulation of carotenoid and anthocyanin mediated by light may help us to explore effective pathways and target genes for improving fruit quality and increasing the accumulation of carotenoid and anthocyanin via genetic engineering and environmental treatments.

Abstract:Nitrogen (N),phosphorus (P),potassium (K),calcium (Ca) and magnesium (Mg) are the mineral nutrients that citrus needs in large number. Insufficient fertilization is not conducive to the growth and development of citrus,nor is it conducive to high yield and quality of fruit. However,with the rapid development of the citrus industry,the application of N,P,K fertilizers have gradually changed from insufficient amounts to generally excessive amounts,which has become a key incentive for the low yield and declining quality of citrus in China. In this paper,the relationships between the yield and quality of citrus fruit and usage of fertilizer were analyzed. It was put forward that the quantification and adjustment of N,P,K rations has become the most urgent practical need. The proper usage is both the high yield and the high quality of citrus fruit. The methods of fertilization and usages of fertilizer for citrus recommended at home and abroad are summarized and compared. A method named as the “determining amount of fertilizer by fruit nutrients removal” method for usage of fertilizer based on the amount of nutrients removal per unit fruit yield and target yield of citrus is proposed. It will be of great significance for guiding citrus production in China.

Abstract:Granulation is a physiological disorder of citrus fruits,which causes juice sac crystallization,reduction of juice,loss of sugar and organic acid,and seriously affects the edible and commercial value of citrus fruits. In this article,the physiological and molecular mechanism in the granulation of citrus fruit is expounded from aspects of cytology,quality and nutrition of fruit,hormone levels,activities of enzymes and molecular biology. It will lay a foundation for further studying the mechanism and control measures in the granulation of citrus fruit.

Abstract:Flavor is an important factor that determines the overall quality of citrus fruit and directly affects consumers’ purchase intentions. Flavoromics is an omics technology to analyze the metabolites basis of flavor quality. The citrus flavor contains many attributes such as sweetness,sourness,aroma,bitterness,texture and offflavor. This article reviews and prospects the origination,strategies,methods and progress of studying citrus flavoromics. It is proposed that the focus of citrus flavoromics should pay more attention to consumer preference and discover the most important metabolites affecting citrus flavor,with a view to targeted cultivation or using cultivation techniques to enhance and improve the quality of citrus fruits in production,and promote the healthy development of the industry.

Abstract:Citrus juice is rich in various minerals and vitamins and has high nutritional value. However,the debittering in citrus juice has always been a main problem faced by the industry of processing citrus. A small amount of bitterness can provide a specific flavor for citrus juice,but the strong bitterness will affect the quality and sales of citrus products. We overviews the biochemical properties,structure,enzymes involved in the catabolic pathway of naringin causing the ‘immediate’ bitterness and limonin causing ‘delayed’ bitterness of citrus juice. It discusses the progress of different physical chemistry and biotechnology of debittering in recent years. The mechanism,advantages and disadvantages of corresponding debittering methods are briefly described. The development trend of debittering technology in citrus juice is prospected.

Abstract:Huanglongbing (HLB) is one of the most devastating disease of citrus worldwide,which has caused huge economic losses.It is caused by phloem limited bacteria Candidatus liberibacters ,and disseminated in orchards by Diaphorina citri (Kuwayama) .At present,the main prevention methods of HLB disease are as follows:first,the traditional “three axes” prevention and controlling strategy,namely,planting pathogen free citrus,removing the infected plants,and large scale successive killing of psylla; second,drug control,mainly including antibiotic drugs，narrow E44spectrum targeted drugs，immune inducers，nano agents and other antibacterial agents.This review systematically discusses the development on drug control of citrus HLB at home and abroad,hoping to provide theoretical basis and reference for the research and development of new drug for citrus HLB.

Abstract:In order to further promote the in depth study on citrus industry economy at the stage of new development in China, this article divides studies on citrus industry economy in China into three stages including initial development (before 1999), steady development (1999-2007) and rapid development (2007 to present). The development process of researching on citrus industry economy in China at each stage is reviewed. The main domestic research achievements are comprehensively summed up from four aspects including production and industrial technology economy, consumption circulation and market, foreign trade and international trade, and industrial macro development and policies. Results showed that the studies on citrus industry economy in China mainly concentrated in aspects including technical and economic analysis, market price analysis, international trade competitiveness analysis and industrial macro development. By combining theory with practice and the continuing indepth study, the team researching on cirtus industry economy in China continues to grow and the achievements are more abundant. The indepth areas to be studied in the future include the transformation and upgrading path of citrus industry to improve quality and efficiency, the adaptability of supply and demand, the environment and policies of international trade, construction of citrus industry economic database and early warning and forecast for production and sales.

Abstract:Six treatments including 70% reduction in phosphorus combined without zinc fertilizer,70% reduction in phosphorus combined with zinc fertilizer,35% reduction in phosphorus combined without zinc fertilizer,35% reduction in phosphorus combined with zinc fertilizer,the habitual amount of phosphorus combined without zinc fertilizer,the habitual amount of phosphorus combined with zinc fertilizer were set up in the white flesh Guanxi pomelo in Pinghe area to investigate the effects of phosphorus reduction combined with zinc foliar fertilizer on the yield and quality of Guanxi pomelo fruit in Pinghe County. The nitrogen,phosphorus and potash fertilizers were orderly applied at the period of flowering (midMarch),steady fruiting (midMay),filling fruiting (late July or early August) and wintering (late November). Foliar zinc fertilizer sprayed during the period of flowering (midMarch) and filling fruiting (late July or early August). Results showed that reducing the amount of phosphate fertilizer increased fruit yield and improved fruit quality. When phosphate fertilizer is reduced by 35%,the fruit yield is increased significantly,and the weight of single fruit and thick skin is significantly reduced. The content of vitamin C,solidacid ratio and other indicators are increased. 35% reduction in phosphorus combined with zinc fertilizer significantly increased fruit yield,comprehensive quality score,fruit juice rate,water content and vitamin C content. Results of field test showed that phosphate fertilizer can be reduced by 35% in Pinghe Guanxi pomelo orchard. Phosphate fertilizer reduction by 35% combined with zinc fertilizer can significantly increase fruit yield and improve fruit quality. The fertilization rate recommended is phosphate fertilizer (P2O5) 0.85 kg/(plant·a),two sprays of 0.2% zinc fertilizer (ZnSO4·7H2O) 40 g/( plant·a).

Abstract:Orange slice is product of dried citrus. Because of its medicinal value and convenience,consumers favor orange slice. Orange slices are easy to be brown in the drying process. In order to better maintain the color of orange slices during processing,the effects of five different color fixatives including ascorbic acid,citric acid,L-E50cysteine,sodium sulfite and βcyclodextrin on browning of orange juice and orange pomace were studied. Different ultrasonic power (300 W,400 W,500W) was used to pretreat and then treated with color fixatives. The product was baked at 70 ℃ for 8 h,and its color was determined every 1 h to explore the best treatment conditions for antibrowning. The contents of vitamin C and reducing sugar in orange juice and orange pomace were determined by titration. The results showed that the vitamin C in orange juice and pomace was oxidized and degraded with the extension of drying time,and the content of reducing sugar increased slightly. The browning degree was inhibited to some extent after adding color protecting agents. 0.20% sodium sulfite treatment had the best antibrowning effect when the color fixatives was treated alone. Combined with ultrasonic pretreatment,the optimal antibrowning effect on orange juice and pomace was 400 W ultrasonic power combined with 0.20% sodium sulfite,which was confirmed on orange segments to have the most obvious antibrowning under this condition.

Abstract:Content of citrus is one of the important factors affecting storage and processing of citrus. Realtime detection of water content of citrus can guarantee the quality of citrus. The visible/near infrared spectroscopy technology,as an increasingly mature nondestructive testing method,can effectively detect the water content of citrus. The Satsuma mandarin picked from the Institute of Forest and Fruit at Wuhan Academy of Agricultural Sciences were placed naturally at room temperature for reducing the water content of the Satsuma mandarin and increasing the water content gradient of the citrus. A spectrum collection device was built with Maya2000pro as a carrier. The score is obtained by dewatering in a super electric heating constant temperature blast drying oven and calculated according to GB 5009.3-2016. The fitting accuracy of partial least squares regression (PLS) model established was compared through the use of differential processing,multivariate scattering correction,standard normal variate,SG convolution smoothing,standardization and other pretreatment methods. Results showed that SNV was the most effective preprocessing method. At the same time,a competitive adaptive reweighted sampling algorithm is used to extract characteristic wavelengths to establish a partial least square regression model,a BP neural network model and a least square support vector machine model based on water content of citrus. The results showed that the LSSVM model established with 359 wavelengths obtained by CARS screening using the spectrum after SNV preprocessing had the best prediction effect. The correlation coefficient and root mean square error of the calibration set are 0.937 5 and 0.008 6,respectively. The correlation coefficient of the verification set and the root mean square error are 0.831 6 and 0.012 0. The natural placement method at room temperature improves the water content gradient of Satsuma mandarin,thereby ensuring the adaptability of the model. It is indicated that the visible/near infrared spectroscopy technology is feasible for detecting the water content of Satsuma mandarin.

Abstract:A pathogenic bacterium was isolated from the diseased Procambarus clarkiin Qianjiang,Hubei Province.The strain was identified by physiological and biochemical assay,16S rRNA sequencing and phylogenetic analysis.Then susceptibility of the strain to antibiotics was performed by the agar diffusion method,and the minimum inhibitory concentrations (MICs) were evaluated by the microdilution method.The results showed that the physiological and biochemical characteristics of the isolated strain were similar to that of Klebsiella pheumonia.The 16S rRNA sequencing and phylogenetic analysis showed that the 16S rRNA sequence of the strain shared over 99% similarities with that of K. pheumonia.Therefore,the strain was identified as K.pheumonia.According to the susceptibility results,the strain was sensitive to cefotaxime and polymyxin B among all the tested antibiotics.These results above indicated that the strain was a multiresistant K. pheumonia strain.

Abstract:A pathogenic bacterium was obtained from the hepatopancreas of diseased Procambarus clarkii.The isolated strain was determined by physiological and biochemical analysis,16S rRNA sequencing and phylogenetic analysis.Then the sensitivity of the strain to 20 kinds of antibiotics and synergistic effects of antibiotics combined with natural compounds were determined by the agar diffusion method and checkerboard assay.The results showed that physiological and biochemical characters of the isolate were similar to that of Morganella morganii,and 16S rRNA sequence determination and phylogenetic analysis showed that the isolate sequence shared over 99% similarity to that of M. morganii.Taken together,the strain was identified as an M. morganii strain.The susceptibility study showed that the strain was sensitive to enrofloxacin,florfenicol,neomycin and other 4 kinds of antibiotics,and moderate sensitive to kanamycin,resistant to doxycycline,streptomycin,tetracycline and other 9 kinds of antibiotics.Moreover,the synergistic susceptibility showed that doxycycline combined with dihydrocapsaicin had synergistic effect.Taken together,the results demonstrated that the strain isolated from the hepatopancreas of diseased P. clarkii is a resistant M. organii.Florfenicol,enrofloxacin,neomycin and doxycycline combined with dihydrocapsaicin can be chosen as candidates for treatment of M. morgani infections.

Abstract:In order to evaluate the safety of imidacloprid to Procambarus clarkii,indoor exposure test and field residual elimination test were carried out,at the recommended mass concentration of 0.2 mg/L. Samples of P. clarkii,paddy mud and field water were collected separately to study the enrichment and residue elimination of imidacloprid in integrated rice and P. clarkii breeding model. The results showed that the order of imidacloprid accumulation in P. clarkii indoor exposure was gill>muscle>hemolymph>intestine>hepatopancreas. In the field residual test,the order of imidacloprid accumulation in P. clarkii was muscle>intestine>gill tissue>hemolymph>hepatopancreas. At the same time,it was found that 28 days after field application,the imidacloprid residue in the muscle tissue was 20.44 μg/kg, the degradation rate of imidacloprid in paddy field water was 97.54%,and the residual amount in the sediment was 10.94 μg/kg. Therefore,in order to avoid harm to the nontarget biological aquatic product-P. clarkii,it is recommended that the application interval of imidacloprid in rice fields should be properly extend,and in rice fields close to the cultured water,especially in the integrated cultivation mode of rice and shrimp,drugs should be applied cautiously or use other alternative.

Abstract:In this experiment,at 18℃ and 2 ℃,enrofloxacin was injected at a dose of 20 μg/kg to study the pharmacokinetics characteristics and residues of enrofloxacin and ciprofloxacin in Procambarus clarkii.The results showed that the recovery rates of enrofloxacin and ciprofloxacin in the hemolymph,muscle,hepatopancreas and pancreas were from 80% to 110%.The intra day variation coefficients of the detection values were less than 5%,and the interday variation coefficients were less than 6%.The detection limits were all below 0.01 μg/mL (μg/g).The Tmax of enrofloxacin in the hemolymph,muscle,hepatopancreas at 18℃ was 0.083 0 h,0.344 7 h,and 1.933 5 h,respectively,and the Tmax of ciprofloxacin was 0.083 0 h,0.263 4 h,and 1.165 8 h,respectively.Increasing the temperature accelerated the absorption of enrofloxacin in P.clacherii.The order of elimination halflife T1/2β was hepatopancreas (55.740 3 h)> muscle (52.743 7 h)> plasma (18.608 7 h).With enrofloxacin and ciprofloxacin as residual markers,the elimination period of enrofloxacin in the hepatopancreas and pancreas was 311.47 h at 25℃,and the elimination period of enrofloxacin in hepatopancreas and pancreas was 417.77 h at 18℃.It is recommended that the enrofloxacin withdrawal period is 325 (℃·d).

Abstract:In order to explore the function and molecular mechanism of sex-lethal gene in Procambarus clarkii,four Sxl cDNA sequences from P. clarkii were obtained using rapid amplification of cDNA ends,and their expression in different tissues and at early developmental stages were detected by quantitative fluorescence PCR. Bioinformatics analyses revealed that PcSxlβ and PcSxlδ were 77 bp longer than PcSxlγ,and the predicted amino acid sequence of PcSxlβ and PcSxlδ were shorter than that of PcSxlγ. The PcSxl sequences was highly similar to that of Cherax quadricarinatus (75.76%). The analysis of conservative domain showed that all the predicted amino acid sequences of the four transcriptional isomers had two highly conservative RRM domains. The expression analyses showed that PcSxl was highly expressed in the antennal glands and gills of adult males,and in the midgut and foregut of adult females,and was significantly higher in the female ovaries than the male testis. During the early developmental period of the crayfish,the expression of the genes was the highest at the nauplius stage,but decreased at the zoea stage; however,the expression level increased at the first day after hatching,and then showed a gradually decreasing trend. The results of this study suggested that PcSx was involved in sexual differentiation in P. clarki.

Abstract:To elucidate the function of the doublesex（PcDsx）gene in Procambarus clarkii ,the PcDsx cDNA sequence was obtained by the rapid amplification of cDNA ends (RACE) and the expression of PcDsx was determined by quantitative realtime PCR (qRT-PCR). The results of bioinformatics analysis showed that the fulllength PcDsx cDNA was 1 584 bp,with a 243 bp 5′ untranslated region,a 765 bp open reading frame (ORF) (coded 254 aa) and a 576 bp 3′ untranslated region. The deduced protein of PcDsx was 254 aa and the predicted PcDsx protein was found to contain a conserved DM domain. Phylogenetic analysis revealed that the PcDsx DM domain share high similarity to the DM domain of Sagmariasus verreauxi doublesex. The gene expression analysis showed that PcDsx was widely expressed in various tissues of the adult crayfish,highest in the antennary glands,followed by the muscle and gonads. The expression of PcDsx in various adult female tissues was significantly different from that in adult male tissues. During the early development of P. clarkii ,the expression level of PcDsx reached a peak at 3 day after hatching,while the highest expression of PcDsx in male and female juveniles appeared at 41 and 115 day after hatching,respectively. Besides,the expression of PcDsx also showed significant differences between male and female juveniles.

Abstract:Rapid detection as an efficient and convenient detection method is considered to be an important means to effectively improve food safety detection and clinical diagnosis capabilities. Magnetic relaxation switching (MRS) biosensor has become a new method and new tool for rapid detection due to its excellent analytical performance and simple analysis process. The development of MRS biosensor began with the discovery of magnetic relaxation. When the state (dispersion or aggregation) of superparamagnetic nanoparticles changes in aqueous solution,the uniformity of its local magnetic field can be changed to form a nonuniform local magnetic field followed by a transverse relaxation speed acceleration of the surrounding water molecules and shortening of the transverse relaxation time. Based on this principle,different biomolecular recognition elements including antibody,enzyme,nucleic acid can be used to assemble MRS biosensor for rapid detection of targets. MRS biosensors can be mainly classified into four types: (1) Magnetic nanoparticles-mediated MRS biosensors,which contain the MRS biosensors based on the state change of magnetic nanoparticles; (2) MRS biosensors based on the number change of magnetic nanoparticles ; (3) MRS biosensors based on the state and number changes of magnetic nanoparticles; (4) Paramagnetic ion mediated MRS biosensors,a novel MRS biosensors based on the spatial dipoledipole interactions between paramagnetic ions (contain multiunpaired electrons) and hydrogen protons. Combined with portable miniature NMR instrument,MRS biosensors can be realized on site quick testing. In this paper,we reviewed the different sensing principles and the progresses of MRS. In addition,we discussed the development and improvement of MRS in the aspects of signal transformation mechanism,the performance of magnetic probe,signal amplification system and biosensor stability. Finally,we discussed the main problems of MRS biosensors. The future development or breakthrough of MRS biosensors in the field of rapid detection was prospected.

Abstract:In order to explore the effects of different plant height,center of gravity height and basal stem traits on lodging resistance of rice,10 traits of 533 rice core germplasm under two cultivation modes including pot culture and field culture were analyzed with correlation and path analysis. The results showed that the first internode wall thickness and basal stem breakingresistant strength of the lowplant rice had synergy on the lodging index,indicating that improving lodging resistance of low-plant rice should focus on the first internode stem thickness and wall thickness. The lodging of high-plant rice is more affected by plant height and height of gravity center,indicating that improving lodging resistance of high-plant rice should concentrate in the second internode stem thickness. The improvement of lodging resistance of rice germplasm with different plant height can be achieved by enhancing the bending strength of rice basal stem. It will provide an important reference for improving lodging resistance of rice with different plant height.

Abstract:The method of isolating and transiently transforming oil palm leaf protoplasts was established. Protoplasts were isolated from leaves of oil palm with 30 g/L cellulase and 8 g/L macerozyme for 3.5 h,and collected by centrifugating at 2 000 r/min for 5 min at 4℃. The dual plasmid transient coexpression system was optimized with green fluorescent protein (GFP) and red fluorescent protein (RFP). The best transformation efficiency was the obtained when the plasmids were mixed with oil palm protoplasts with the mass ratio of 8∶1,heat shocked at 45℃ for 20 min after placed on ice for 30 min,and incubated at room temperature under the dark condition for 30 min with equal amount of PEG/Mg2+ (200 g/L PEG 4000 and 100 g/L MgCl2). It will provide a novel method for further identifying the function of the genes from oil palm.

Abstract:The contents of heavy metals Cd,Hg,As,Pb,Cr,Cu,Ni and Zn were monitored in the surface soils at 208 monitoring points in the area studied. The environmental baseline values of heavy metals and the cumulative changes of the baseline value relative to the background value were obtained. Based on this,the degree of disturbance of heavy metals in the regional surface soil by human activities can be judged. Standardized methods and relative cumulative frequency statistics were used to acquire the environmental baseline value and deviation of heavy metals in regional surface soil. The average environmental baseline values obtained by these two methods were used as the environmental baseline values of heavy metals in the surface soil of the area studied. The contents of heavy metals Cd,Hg,As,Pb,Cr,Cu,Ni,Zn exceeded the risk screening values for soil contamination of agricultural land of monitoring points in regional surface soil. The ratio of monitoring points was 17.3%,1.0%,4.3%,0.0%,2.4%,3.8%,1.9%,E95and 0.0%,respectively. Compared to the regional background values,the heavy metals had accumulated to different degrees of monitoring points in regional surface soil,and the ratio of monitoring points was 26.9%,26.0%,29.8%,17.3%,16.8%,20.2%,28.4%,and 21.6%,respectively. The mean environmental baseline value of heavy metals Cd,Hg,As,Pb,Cr,Cu,Ni and Zn obtained by the standardized method and the relative cumulative frequency statistics was 0.22 mg/kg,0.09 mg/kg,13.34 mg/kg,30.7 mg/kg,82.0 mg/kg,29.7 mg/kg,38.0 mg/kg and 89.1 mg/kg,with the relative deviation ranged from 0.5% to 12.0%. According to accumulation index of heavy metal,the environmental baseline values of heavy metals Cd,Hg,As,Pb,Cr,Cu,Ni,Zn increased to different degrees relative to the regional background values of the monitoring points in regional surface soil. The increasing change rate was less than 50%,which was not significant. The cumulative index of environmental baseline value of heavy metals Cd,Hg,As,Pb,Cr,Cu,Ni and Zn was 1.5,1.2,1.0,1.1,1.0,1.0,1.0,and 1.0,respectively. Among them,the environmental baseline value of heavy metal Cd is slightly accumulated compared to the regional background value,indicating that the soil heavy metal Cd has been disturbed by a certain degree of human factors,but the impact is small. The heavy metal Hg had slight risk of accumulation,and the heavy metals As,Pb,Cr,Cu,Ni,Zn had no obvious accumulation.

Abstract:A field experiment with two treatments including NK (-P) and NPK (+P) was conducted in 2011 to study the effects of long-term application of phosphorus (P) fertilizer on the phosphorus fractions and microbial diversity of rice-rapeseed rotation. The soil layer was divided into 0-10、10-20、20-3+E1070 and 30-40 cm for sampling and analyzing. Soil available P,total P and organic P were determined with conventional analytical methods. Chemical continuous extraction method was used to determine the inorganic P fractions in the soil samples,and Illuminamiseqpe 250 platform was used for high-throughput sequencing of surface soil (0-10 cm) microorganisms. The results showed that long-term application of P fertilizer (+P) significantly increased the content of total P,inorganic P and available P in each soil layer compared with the CK (-P treatment),but the organic P content did not increase significantly. P content in soil layer of 0-10 cm and 10-20 cm significantly increased by application of P fertilizer,but the effect on the bottom layer of 20-30 cm and 30-40 cm was not obvious. Compared with -P treatment,long-term application of P fertilizer reduced the alpha of microbial community diversity and changed the structure of microbial community. At the level of phylum,the dominant bacteria were Chloroflexi,Acidobacteria and Proteobacteria. The relative abundance of Chloroflexi and Acidobacteria was increased,while that of Proteobacteria decreased. Ascomycota and Basidiomycota were the dominant phylum,the relative abundance of Ascomycota decreased and that of Basidiomycota increased. Compared with CK,although the application of P fertilizer significantly decreased the number of bacteria and fungi in the layer soil in each taxa,the relative abundance of the dominant flora decreased from the perspective of the genus level. The results of analyzing redundancy showed that the content of Al-P and Fe-P was closely related to the abundance of various bacteria and fungi. It is indicated that long-term phosphorus deficiency induce an increase in the number of microorganisms to activate soil nutrients,and a sufficient supply of phosphorus fertilizer meet crop nutrient requirements and maintain the dynamic balance of soil microbial communities. Therefore,it is necessary to optimize the application of P fertilizer in the entire crop rotation system to promote the activation and release of soil phosphorus,thereby reducing the amount of P fertilizer and improving its recovery rate.

Abstract:The effects of soil acidification on soil nutrient availability and plants nutrient uptake,accumulation and distribution were investigated to provide a basis for soil acidification treatment,especially nutrient efficient utilization. Cherry tomatoes (Lycopersivon esculentum Mill) was used to conduct pot experiment with acidic red soil (pH 5.05). The soil pH was adjusted to 4.0,5.0,6.0 and 7.0 with citric acidsodium hydrogen phosphate buffer and sodium carbonate-sodium bicarbonate buffer. There were 4 treatments with 5 replicates per treatment in the experiment. The results showed that measured soil pH were 4.35,4.92,5.89,6.85,adjusted down by 0.70,0.13 and increased by 0.84 and 1.80 pH unit,respectively. Soil acidification significantly reduced the leaf area and biomass of cherry tomato,especially the root biomass,and root to shoot ratio. Soil acidification severely inhibited the accumulation of N,P,K,Mg and Fe in roots,promoted the accumulation and distribution of Fe and Mn in stem,and Ca and Mg in leaves. Soil acidification significantly decreased accumulation of N,P,K,Ca,Mg and Fe in roots. More N,K,Fe and Mn was accumulated in stems,more P,Ca and Mg was accumulated in leaves. Particularly,Mn concentration in all parts of plants was raised significantly. It is indicated that the root is the most severe and sensitive part of whole tomato plant inhibited by soil acidification and most nutrients are absorbed by the roots. Soil acidification blocked migration and reduced accumulation significantly.

Abstract:In order to reveal the importance of leaching on mountainous nutrients cycling,the characteristics of altitude distribution of soil C and N in the coniferous forest at an altitude of 2 600-3 200 m on the eastern slope of the Gongga mountain were studied. The soil C,N content and C/N of the conifers at 4 sampling points at different altitudes were analyzed. Combined with other soil physical,chemical and biological indicators,the effects of the leaching process on the characteristics of altitudinal distribution of soil C and N were explored. The results showed that the spatial distributions of C,N contents and C/N in the humified litter horizon (OH horizon) exhibited a similar decreasing trend with the increase of altitude. Since the content of C in litters (Clit) was positively correlated with soil C and N in the OH horizon（P<0.05）,the production of Clit was the main factor affecting the altitudinal distributions of soil C and N in the OH horizon. The obvious altitudinal trend was not observed for soil C,N contents and C/N in the mineral horizons (A,B and C horizon). The contents of soil C and N in the A horizon were lower than those in the 2 781 m site,while the maximums were for the B and C horizon in this site. The contents of soil C and N in the rainfall were significantly lower than those in the interflow,which showed the effects of leaching on the spatial distributions of soil C and N. It is indicated that the effects of leaching process on the spatial distributions of soil C and N in subalpine coniferous forest in Southwest Asia can not be ignored.

Abstract:The mineralogy and geochemical composition of the cutan and matrix soil in the S5-1 pedon at the Wugong section on the southern Chinese Loess Plateau (CLP) was investigated to provide more insight in the characteristics and environmental significance of the cutan in the S5. The broad band between 400-800 cm-1 in the Raman spectrum of the dark cutan was attributed to the groups of Fe and Mn hydroxide/oxide. Enrichment of Mn and free iron (Fed) in the cutan confirmed the presence of Fe-Mn cutan in the S5-1 pedon which signified a periodic reduction under waterlogged conditions during the pedogenesis of S5-1 pedon on the southern CLP. The low permeability of S5-1 pedon as a result of lessivage of clay fraction characterized by high bulk density and low total porosity made the development of a seasonal perched water table possible. It provided favorable environmental conditions for the formation of Fe-Mn cutan. However,the low Mn/Fe ratio in the cutan indicated that the separation and accumulation of iron and manganese in the S5-1 pedon was not up to the level of typical Fe-Mn cutan from subtropical regions. Silicate minerals in the Fe-Mn cutan was almost identical to the matrix soil. The difference of chemical weathering between the cutan and the matrix soil reflected by the Fed/Fet ratio was not epitomized by the mineralogical composition. The subtropical climate prevailed on the southern CLP during the pedogenesis of S5-1 pedon was further confirmed by the occurrence of Fe-Mn cutan.

Abstract:Rice is one of the staple food crops in China and one of the three staple food crops all over the world. The combine harvester has been widely used due to the improved level of riceharvesting mechanization year by year. The longitudinal axialflow threshing and separating device is of widespread use in combine harvester because of its advantages of long threshing time,soft threshing process and good adaptability. However,the device has the disadvantages of high power consumption,broken stalks and high content of impurity. The power consumption of the device plays an important part in the combine harvester. The researches on energy saving and consumption reduction have great significance for developing combine harvester with large feeding capacity,lightweight and high efficiency. In order to reduce the power consumption and blockage of threshing roller,then improve the harvesting efficiency of rice combine harvesters,a new longitudinal axialflow threshing roller with drum-shaped rod-E130tooth was designed based on the idea that the power consumption of the threshing roller can be reduced by improving the uniformity of the longitudinal axialflow threshing roller power consumption along the axial direction. Its structural parameters and motion parameters were determined by analyzing the working principle of the device. The models of power consumption and threshing roller dynamic were established by observing the process of threshing and separation. Based on the EDEM simulation analysis,the instantaneous total torque of rotating shaft of threshing roller with time was simulated and studied with feeding rate of 1.2 kg/s and rotating speed of 1 100 r/min. Taking the total torque of the rotating shaft of the threshing roller as the test index,the performance of the two kinds of rollers was compared with the feeding rate of 0.8 kg/s,1.2 kg/s and 1.6 kg/s. The results showed that the total torque of the rotating shaft of the threshing roller increased with the increase of the feeding rate for the same roller size and motion parameters. When the feeding rate increases from 0.8 kg/s to 1.6 kg/s,the total torque of the drumshaped threshing roller rotating shaft increases from 38.12 N·m to 118.99 N·m,and the cylindershaped threshing roller increased from 60.13 N·m to 189.91 N·m. Under the same feeding rate,the total torque of rotating shaft of drumshaped threshing roller is lower than that of cylindershaped threshing roller. The performance testing platform of a small longitudinal axialflow threshing and separating device was designed and built. The power consumption comparison bench test of two kind structures of threshing roller under conditions consistent with the simulation was carried out. The results showed that the power consumption of drumshaped threshing roller and cylindershaped threshing roller increased from 4.88 kW to 11.20 kW and from 5.58 kW to 12.20 kW in the feeding rate range of 0.81.6 kg/s. Compared with the cylindershaped threshing roller with the same external size,the power consumption of drumshaped threshing roller is lower than that of cylindershaped threshing roller. The results of bench test and simulation are basically consistent. It will provide a reference for designing the drum structure of the rice lowpower threshing roller.

Abstract:Parameters of physical and mechanical characteristics are indispensable in designing potato minituber related mechanical equipment planter and classifier.Parameters of the contact mechanics are indispensable in developing simulation technology as well.The virusfree potato minitubers (referred as “minituber”) including “Daxiyang”,“Zhongshu No.5” and “Huashu No.1” and the relevant parameters required for discrete element software EDEM in potato minituber were used to measure physical parameters and contact mechanical parameters of three kinds of potato minitubers.Selfmade equipment was used to measure and calculate the triaxial dimensions,weight,radius of curvature,density,Poisson's ratio and shear modulus.The contact mechanical parameters of three kinds of minitubers and three materials (steel plate,ABS and the same variety potato minitubers) including the collision recovery coefficient were measured by using a self-made collision device.The static friction coefficient was measured by using the method of sliding on an inclined plane.The combination of rolling on an inclined plane and highspeed photography was used to record the rolling distance and measure the rolling friction coefficient of potato minituber,steel plates or ABS.The response surface method was used to design the test by using coefficient of static friction and coefficient of rolling friction as test variables,and the stacking angle as test index.The parameters measured in the above experiment were input into the EDEM for simulation to obtain coefficient of the rolling friction in minitubers.Using the stacking angle as the response value,and the credibility of the simulation results was verified by raising a round pipe slowly.Results showed that density,shear modulus and Poisson’s ratio had little correlation with the basic parameters of physical characteristics of minitubers.The triaxial dimensions,weight and radius of curvature were quite different.The varieties were different as well.The contact mechanical parameters of the three types of minitubers and their own same variety were lower than those of the steel plate and ABS.The coefficients of static and dynamic friction of the three types of minitubers and ABS were higher than that of the steel plate.The collision recovery coefficient showed the opposite trend.ABS was lower than the steel plate.The contact mechanical parameters of “Daxiyang” were higher than those of “Zhongshu No.5” and “Huashu No.1”.Among the three materials,the contact mechanical parameters with the steel plate were the largest,indicating that its elastic recovery performance is the best,with relatively large friction and relative difficulty to be damaged.The fluidity and the mechanized seeding performance was poor.The difference of contact mechanical parameters between “Zhongshu No.5” and “Huashu No.1” was small.The measurement results of different varieties of minitubers were quite different.Users can select the required parameters in the text according to their needs.The variety should be fully considered in the design and simulation calculations.Compared with the actual accumulation angle of the experiment,the simulation results of different varieties of potato minituber were less than 3%,indicating that the results are reliable and the actual parameters of the minituber particles measured can be used as simulation parameters in the EDEM software.

Abstract:Biomass gasification is a technology that converts biomass into gas fuel. However,complex tar compounds will be formed in the process,resulting in reduced gasification efficiency and blockage of downstream equipment. Catalytic steam reforming has been widely used for tar removal. Nickelbased steam reforming catalysts have attracted people’s attention due to its high activity and low cost. Among them,deactivation caused by coke deposition is the biggest challenge of this technology. The nickel-based catalyst came into being. The loading of metal Ni in the modified nickel-based catalyst not only affects the activity of the nickel-based catalyst,but also restricts the preparation cost. At present,there is no report on the steam reforming of biomass tar with a catalyst supporting Ni-Mg active components on the by-E143product RHA (rice husk ash,RHA) of biomass pyrolysis in the treatment of tar with nickel-based catalysts. This article introduces a promoter and RHA as a carrier to improve the catalytic performance of the catalyst. It will be of great significance for improving the economic efficiency and anti-coking performance of the catalyst. Biomass combustion product of rice husk ash was selected as the carrier,and Ni-Mg/RHA catalyst was prepared by co-impregnation method. The catalytic performance of Ni-Mg/RHA for steam reforming of toluene was studied using toluene as a model compound of biomass tar. The effects of Ni and Mg loadings,reaction temperature and S/C ratio on toluene conversion and gas product composition were investigated in a fixed-bed reactor. The catalysts before and after reaction were characterized by XRD,BET and SEM. The results showed that RHA as a support of single metal Ni-based catalyst had a certain catalytic activity. Compared with Ni/RHA and Ni/HZSM-5,RHA is a biomass combustion product with small specific surface area and simple pore size structure. In the Ni/RHA catalyst,the active metal is gathered in the outer layer of the catalyst,and there is no porous structure inside. After catalytic reforming of toluene,carbon deposition is easy form to cover the active site,resulting in the low catalytic activity of Ni/RHA catalyst supported by single metal Ni. After adding MgO modification,the catalyst surface area and pore volume was increased and the surface generated porous structure,indicating that the MgO load improved the specific surface area and pore volume of RHAsupported catalyst providing more reaction sites for toluene and water vapor. Results of crystal structure analysis showed that after adding MgO style,Ni characteristic peak did not appear on the Ni-Mg/RHA. NiMgO characteristic peak,peak diffraction angle shifted to the left. Because of the interaction between NiO and MgO style,NiMgO crystal phase structure more easily formed under the low degree of diffraction is detected,indicating that MgO style improves the dispersion of active metal Ni and provides NiMgO solid solution activity sites,which improved the catalytic performance. When Mg load was 6%,the performance was the best,with the toluene conversion rate of 98.6%. The optimal reaction temperature of 3Ni-6Mg/RHA catalyst was 700℃ and S/C was 3,having good catalytic stability. The optimal reaction temperature of 3Ni-6Mg/RHA was 700 ℃ and S/C was 3,having good catalytic stability. The feasibility of using rice husk ash as the support of nickelbased catalyst in the presence of MgO is confirmed.

Abstract:The yield of rice is closely related to the panicle number and the panicle weight of rice. The accurate prediction of rice yield can accelerate the speed of breeding. In order to study the relationship between rice yield and rice phenotypic characteristics,the visible light images combined with image processing technology was used for extracting feature of potted rice. 51 phenotypic traits of whole rice were obtained. Combined with deep learning technology,the Faster R convolutional neural network training model was used to detect the number of rice spikes. At the same time,the SegNet model was trained using the SegNet network framework to segment the rice spikes to obtain the binary image of the rice spikes. 33 phenotypic feature data of the panicle were extracted with image processing technology. A total of 85 phenotypic parameters of color,shape,and texture were extracted,and all 85 data were normalized. The 85 phenotypic data normalized were gradually linearly regressed with the fresh and dry quality of rice panicle,and the correlation was selected. The artificial measurement data in the experiment included the fresh weight and dry weight of potted rice panicle. The models of predicting fresh and dry panicle weight of potted rice were established separately by using panicle number and characteristic panicles,51 characteristics of whole plants and all 85 characteristics of high correlation characteristic data. The prediction model was optimized according to the determination coefficientR2,mean relative error (MAPE) and standard deviation of absolute relative error (SAPE). The optimal prediction model was selected according to the decision coefficient R2,average relative error (MAPE) and standard deviation of relative absolute value (SAPE) of the model. The results of prediction showed that the effect of predicting panicle characteristics is the best. The decision coefficients R2 of the predicted value and the real value of the model with the best effect are 0.787±0.051 and 0.840±0.054,respectively. Combined with deep learning,the number and characteristics of panicle difficult to obtain automatically by traditional methods are extracted. It will provide a new idea and method for predicting rice panicle weight,and further improving the accuracy of predicting rice panicle weight.