Time effects of rice straw and engineered bacteria on reduction of exogenous Cu mobility in three typical Chinese soils

Hanzhi SHIDian WENYongdong HUANGShoujun XUTenghaobo DENGFurong LIZhichao WUXu WANGPeihua ZHAOFuhua WANG and Ruiying DU

1Institute ofQualityStandardandMonitoring Technologyfor Agro-Products,Guangdong AcademyofAgricultural Sciences,Guangzhou510640(China)

2KeyLaboratoryofTesting andEvaluation for Agro-Product SafetyandQuality,MinistryofAgriculture andRural Affairs,Guangzhou510640(China)

3Guangdong Provincial KeyLaboratoryofQuality&SafetyRisk Assessment for Agro-Products,Guangzhou510640(China)

ABSTRACT Globally,copper(Cu)accumulation in soils is a major environmental concern.Agricultural organic waste and some bacterial species can readily absorb metals in an eco-friendly manner,and thus are commonly used in metal-contaminated soil remediation.This study investigates the change in Cu fractions during the aging process and the time effects of rice straw(RS)and engineered bacteria(EB)(Pseudomonas putida X4/pIME)on reduction of Cu mobility.Three typical Chinese soils(red,cinnamon,and black soils)were incubated with RS or RS+EB in the presence of exogenous Cu for 24 months.The soil physicochemical properties,reactive soil components,Cu fractions,and Cu mobility were determined over time.The Cu mobility factor(MF)values were the lowest in the black soil(6.4–9.2)because of its high organic carbon and clay contents.The additions of both RS and RS+EB accelerated Cu stabilization during the aging process in all three soils.The Cu MF values decreased with time during the initial 20 months;however,the MF values increased thereafter in all soils,which might be due to the reduction of humic substances and amorphous iron oxides and the increase in iron oxides complexed on the organic matter.The reduction rates of Cu MF were similar after 16,24,and more than 24 months in the red,cinnamon,and black soils,respectively,indicating that RS and RS+EB could limit Cu mobility at different times in various soils.The RS treatment showed the greatest efficiency in reducing Cu mobility in the red,cinnamon,and black soils after 12,12,and 8 months of incubation,respectively.The RS+EB treatment was more efficient than the RS treatment in the red soil during the initial 8 months of the incubation period.Our study provides theoretical support for Cu risk assessments and RS supplementation for Cu remediation in different soils.

KeyWords: aging,Cu distribution,mobility factor,sequential extraction,soil incubation

INTRODUCTION

Anthropogenic activities,such as mining,agriculture,and industry,have caused metal accumulation in soils,which severely threatens agricultural production and food safety worldwide(Kuoet al.,2006;Bolanet al.,2014;Liet al.,2014;Wuet al.,2018;Caiet al.,2019).Metals contaminate approximately 20 million hectares of cropland and 12 million tons of cereals in a single year in China(Li Get al.,2011;Li Z Get al.,2011).As one of the most common metals,Cu is an essential nutrient at low levels;however,it may be harmful to animals,plants,and humans at elevated concentrations(Oliver,1997;Cuiet al.,2008;Zhouet al.,2018).

The specific chemical forms and binding patterns of metals largely determine their mobility,bioavailability,and ecotoxicity; hence, estimating the total metal content is insufficient for evaluating the actual environmental risk.The sequential extraction of metals in soil using specific chemical extractants to obtain different fractions bound to solid soil components is an effective method for determining the chemical forms of metals(Doelschet al.,2008;Bogusz and Oleszczuk, 2018). This is potentially advantageous for predicting metal mobility, cycling in the food chain,and availability to plants (Shaheen and Rinklebe, 2014;Bogusz and Oleszczuk,2018).Among the various extraction protocols,Tessier’s five-step sequential extraction procedure is widely used because of its high selectivity and efficiency;it also allows for rapid risk assessment.Moreover,researchers have used a modified Tessier extraction method, which uses water-soluble extractable and humic substance-bound forms of metals, to obtain detailed information about the distribution of metals among soil components(Tanget al.,2006;Shiet al.,2018).

Agricultural waste contains hydroxyl,carboxyl,and other functional groups,and can absorb Cu from the soil because of its loose and porous structure.Hence,amending soil with organic matter (OM) may affect the distribution of Cu in the soil(Daiet al., 2018). Composition or mineralization destabilizes the total content of soil OM; thus, Cu bound to OM is adsorbed or released during the aging process(Venegaset al.,2016).Previous research has indicated that solid OM has a high chemical affinity for Cu.In an almost neutral soil(pH 6)with a Cu concentration of 34 mg kg-1,the most dominant Cu species were Cu(II)-organic complexes;they varied from 50%to 100%with the application of pig manure compost,sewage sludge,and solid waste compost at a rate of 80 t ha-1after a 120-d incubation period(Tellaet al., 2016). Dissolved OM (DOM) can promote metal solubility.Beesleyet al.(2010)determined that green waste compost and biochar can affect the Cu concentration of pore water in a mildly acidic soil (pH 5.45). In a 56-d incubation experiment, the Cu concentration in the soil solution increased by 13–33 times with the addition of organic amendments as a result of the increase in dissolved organic carbon (OC). Copper mobility is also influenced by the addition of organic agricultural materials.Sánchez-Martínet al.(2007)found that Cu mobility decreased by 18%to 21%with the application of 20 and 200 g kg-1sewage sludge to soils,respectively.In contrast,the introduction of municipal solid waste compost did not significantly affect the mobility of Cu during a five-year experiment(Achibaet al.,2009).

When Cu enters the soil,it is initially rapidly adsorbed or precipitated.This is followed by a slow reaction,during which the extractability, mobility, and toxicity of Cu decrease during the aging process. Many factors affect the above reactions,including soil components,soil properties,and environmental factors(Jalali and Khanlari,2008; Maet al.,2013;Liet al.,2018;Yuet al.,2018).In a loamy soil with pH of 6.9 and OM of 43.5 g kg-1,the exchangeable Cu dramatically decreased by 18%in three days;however,the rate of decrease of Cu in this fraction became slower thereafter.Approximately 29%of the exchangeable Cu remained after a 56-d incubation period(Luet al.,2009).In 10 artificial soils with pH of 5.5–7.5,OM of 1%–30%,and clay of 5%–35%,Daoustet al.(2006)found that pH was the primary factor that controlled Cu mobility during a 16-week incubation period.Similarly,Maet al.(2006)indicated that the exogenous Cu attenuation rate was faster in soils with pH＞6.0 than in soils with pH＜6.0.

Moreover,the quantity of bacteria in soils is vast,and the surfaces of bacterial cell walls contain multitudinous organic metal binding groups,including carboxyl,phosphate,amino,sulfhydryl,and hydroxyl groups.Therefore,bacteria can greatly influence the interfacial binding behavior of metals (Feinet al., 1997; Duet al., 2018). To the best of our knowledge, previous studies have focused on the aging mechanism of Cu over a period of a few days or months,but aging studies including the addition of organic or bacterial amendments are lacking.However,a few studies have investigated the time effects of organic or bacterial amendments on Cu mobility.

In our previous study (Shiet al., 2018), the factors influencing Cu fractions were investigated during a 12-month incubation period in red(Ultisol),cinnamon(Alfisol),and black (Histosol) soils. Briefly, the three typical soils were treated with exogenous Cu and rice straw (RS) or RS+engineered bacteria(EB).The Cu fractions and soil properties were analyzed using multiple linear regression analysis.The results indicated that the contents of soil OM and iron oxides played important roles in controlling Cu fractions in red and cinnamon soils,respectively,indicating that changes in soil components with low content may have a greater contribution to changing Cu fractions.

This study,an extension of our previous study(Shiet al.,2018),investigated Cu fractions over a long incubation period and the time effects of organic and bacterial amendments on Cu mobility.We hypothesized that i)black soil will have the lowest Cu mobility because of its high OC and clay contents,ii)the mobility factors(MF)values will decrease because Cu is increasingly adsorbed with time,and iii)the addition of EB will improve Cu retention.The aim of this study was to observe the changes in Cu fractions during the aging process and to observe the time effect of RS and EB on Cu mobility.

MATERIALS AND METHODS

Sampling andsoil characterization

Three common soil types, red soil (Ultisol), cinnamon soil(Alfisol),and black soil(Histosol),were collected from Hunan, Henan, and Heilongjiang provinces, China,respectively.Soil samples were air-dried,ground,and passed through a 2-mm sieve.The soil physiochemical properties were determined following previously published methods(Bao, 2000; Lu, 2000; Shiet al., 2018). In this study, the soil pH ranged from 5.79 to 7.43,and the soil OM content varied from 6.70 to 55.16 g kg-1(Table I).

Soil treatment andincubation

The three soils were incubated with RS and RS +EB (Pseudomonas putidaX4/pIME) in the presence of exogenous Cu for 24 months.Soil treatment and incubation procedure were described in our previous study(Shiet al.,2018).Briefly,after passing the soil through a 2-mm sieve,1 kg of air-dried soil was added to a ceramic pot.Rice straw was ground to less than 1 mm and mixed into the soil at a rate of 50 g kg-1.The same amount of RS was added in the RS and RS+EB treatments.The EB,which consisted of a monkey metallothionein surface displayed onPseudomonasputidaX4/pIME, was used at a rate of 1× 107colonyforming unit(CFU)g-1(Heet al.,2012).After amendment with RS or RS+EB,Cu(NO3)2was added to the soil at a rate of 200 mg kg-1,and then each soil sample was mixed thoroughly.Soil samples spiked with only the Cu solution(with no amendment)were prepared as a control.The pots were then deposited in a greenhouse maintained at 25°C.The pots were weighed periodically,and the weight was adjusted with distilled water to maintain the soil water content at a water-holding capacity of approximately 60%.The soil in each pot was homogenized prior to sample collection,and approximately 80 g of soil was sampled from each pot every four months.

TABLE I Physicochemical properties of the three typical Chinese soils used

Sequential extraction ofCu

Modified Tessier procedures were conducted to evaluate the Cu distribution in the soils(Tessieret al.,1979;Tanget al.,2006).Copper was classified into water-soluble(WS-Cu),exchangeable(E-Cu),specifically adsorbed/carbonate-bound(SP/CA-Cu),humic acid-bound(HA-Cu),iron-manganese oxide-bound(Fe/Mn-Cu),strong organic-bound(SO-Cu),and residual-bound(RES-Cu)categories.A detailed description of the extraction method is provided in our previous study (Shiet al., 2018). A flame atomic absorption spectrometer(Z-2000;Hitachi,Japan)was used to measure the metal concentration in the supernatant.

The MF was calculated using Eq.1,which was introduced to estimate the proportions of extracted metals in labile forms(Salbuet al.,1998;Narwalet al.,1999):

Statistical analysis

All incubation experiments were performed in triplicate.The data presented as mean with standard error were subjected to analysis of variance(ANOVA)tests,and Duncan’s test was used to compare means.In all tables and figures,the mean values denoted by different letters are significantly different(P ＜0.05).

RESULTS

Aging effect on the Cufractions in the soils

The proportions and contents of Cu fractions in the control with no soil amendments are shown in Fig.1 and Fig.S1(see Supplementary Material for Fig.S1).The contents of WS-Cu showed limited changes during the incubation period for all studied soils.The cinnamon soil contained the highest WS-Cu, whereas the black soil contained the lowest. The E-Cu fraction showed a small increase from months 4 to 8,followed by a decrease during the late incubation period.Generally,the decrease occurred faster in the two acidic(red and black)soils.In addition,SP/CA-Cu was generally reduced in month 20 and was elevated thereafter.The total reduced amounts of SP/CA-Cu in the red and cinnamon soils were approximately 30 mg kg-1throughout the entire duration of the experiment,which was 10 times that in the black soil(approximately 3 mg kg-1).Moreover,the HA-Cu contents in the red and cinnamon soils with low OM contents were much lower than that in black soil.In the red and cinnamon soils,HA-Cu varied from 38 to 60 mg kg-1from months 4 to 8,and constantly increased until the end of the incubation period,reaching 130 mg kg-1.After month 4,the Fe/Mn-Cu contents were similar in the three soils.In the red and black soils, the Fe/Mn-Cu contents increased from months 4 to 8 and declined thereafter.In the cinnamon soil,Fe/Mn-Cu increased from months 12 to 20,and then decreased until the end of the incubation period.The RES-Cu increased in all studied soils.The equilibrium time was 20 months for the red and cinnamon soils;however,in the black soil,RES-Cu remained elevated until month 12 and then decreased.

Effects ofamendments on Cudistribution during aging

Amending soil with RS and RS+EB played a vital role in the proportions and contents of individual fractions of Cu(Fig.1 and Fig.S1).Among the three soil types,the trends of the Cu fractions over time were similar to those found for the control.However,some differences in the Cu fractions were found in the amendment treatments.At the beginning of the study,the RS and RS+EB treatments increased the WS-Cu contents by 4.4–13.6,1.9–4.2,and 0.5–3.0 times in the red,cinnamon,and black soils,respectively.The proportion of SP/CA-Cu was significantly reduced by 11%–35%,37%–56%,and 11%–64%in the red,cinnamon,and black soils,

Fig.1 Proportions of Cu fractions in three typical Chinese soils incubated with different amendments in the presence of exogenous Cu for 24 months.The sampling time(month)is indicated above the columns.CK=no amendment as a control;RS=rice straw;EB=engineered bacteria;WS-Cu=water-soluble Cu;E-Cu=exchangeable Cu;SP/CA-Cu=specifically adsorbed/carbonate-bound Cu;HA-Cu=humic acid-bound Cu;Fe/Mn-Cu=iron-manganese oxide-bound Cu;RES-Cu=residual-bound Cu.

respectively.In addition,E-Cu was lower than the control in the red and black soils with the decrease rates of 18%–67%and 24%–64%,respectively.In contrast,E-Cu increased by 79%–160% in the cinnamon soil when RS and RS + EB were applied.Furthermore,increase rates of 22%–68%and 17%–24% were found for the HS-Cu contents in the red and cinnamon soils,respectively,compared to those in the control.A 24%–45%decrease in RES-Cu was observed in the red soil after 12 months of incubation. However, the RES-Cu in the cinnamon soil increased by 10%–39%during the 24-month incubation period. With the applications of RS and RS + EB in the black soil, RES-Cu increased by 14%–44% in the last 8 months of the incubation period.There was no significant difference in Fe/Mn-Cu between the control and amendment treatments in all soils.

Cumobility

The time dependence of the Cu MF values in the three soils under different amendment treatments is illustrated in Fig.2.Briefly,the Cu MF value in the cinnamon soil with the total extractable Cu being approximately 44.3% was higher than that in the other two soils. The Cu MF value was the lowest in the black soil at all six time points(less than 10.0).After 24 months of incubation,the Cu MF values were similar in the red and cinnamon soils.

Overall,the Cu mobility was the lowest after 20 months of incubation in all soils under all treatments(Fig.2).The Cu mobility decreased in all three soil types under the RS treatment,and was identical in the red and cinnamon soils.The reduction rates in Cu mobility for amendment treatments were calculated by comparision with the control (Fig. 3).The extent of the mobility reduction was related to the soil type and incubation time. The reduction rates in the RS treatment were 13.8%and 20.8%in the red and cinnamon soils,respectively,after 4 months of incubation.These values almost doubled after 8 months of incubation in the red and black soils.The reduction rates of RS treatment decreased after 12 and 8 months in the red and cinnamon soils and black soil,respectively.In addition,the Cu mobility did not show a statistically significant change in each soil undergoing the RS+EB treatment,in contrast to those undergoing the RS treatment.

Fig.2 Copper mobility factor(MF)values of three typical Chinese soils incubated with different amendments in the presence of exogenous Cu for 24 months.CK=no amendment as a control;RS=rice straw;EB=engineered bacteria.Vertical bars are standard errors of means(n=3).

Fig.3 Reduction rate in Cu mobility induced by different amendments(reduction in mobility factor(MF)in comparison with MF of the control(no amendment))of three typical Chinese soils incubated in the presence of exogenous Cu for 24 months.Vertical bars are standard errors of means(n=3).RS=rice straw;EB=engineered bacteria.

Considering the time effect,the Cu mobility decreased steadily over 20 months; however, a slight increase was observed after 24 months of incubation in the three types of soils with different amendments(Fig.2).At the end of the experiment,the RS treatment decreased Cu mobility by 17.9%and 25.1%in the red and cinnamon soils,respectively,compared to that in month 4(Table II).The reduction rates of Cu mobility in the red,cinnamon,and black soils were similar among the three treatments after 16,20,and more than 24 months,respectively(Table II).

DISCUSSION

Cumobilityin three soils

The Cu mobility is affected by both soil properties and incubation time. We found that the MF value of the alkaline cinnamon soil was the highest(Fig.2). This was surprising because carboxylic groups associated with soil OM should be deprotonated(–COO-)at this pH;hence,it should electrostatically attract the Cu2+cation. However,the soil has very little OM,while pedogenic oxides would still have a largely positive charge (assuming a point of zero charge pH of 8.5 for common Fe-oxides).Therefore,we suggest that the cinnamon soil, which has a very low clay content(approximately 8%)and associated low cation exchange capacity(CEC),has a low sorption capacity for cations,including Cu2+.

The Cu mobility in the red soil was slightly lower than that in the cinnamon soil, but was generally of the same order of magnitude.The levels of soil OM and CEC were similar in these two soils,and the iron oxide contents(Tables SI,SII,and SIII,see Supplementary Material for Tables SI,SII, and SIII) in the red soil were about two times those in the cinnamon soil.The low OM and positive charge of iron oxides in the red soil resulted in a relatively higher Cu mobility.In addition,the clay content(18.8%)was higher than that in the cinnamon soil,which may have resulted from the lower Cu mobility in the red soil than in the cinnamon soil.

Of the three soils,the black soil had the lowest MF(＜10.0),indicating that the black soil is superior in reducing Cu mobility.This could be because the black soil had the highest levels of OM,CEC,and clay,which is in accordance with our first hypothesis.

Effects ofamendments on Cumobility

Considering the effects of amendments on the mobility of Cu, we found that the RS and RS + EB treatments accelerated the reduction in Cu MF (Fig. 3). Moreover,the RS and RS+EB treatments always caused the largest decrease in MF in the cinnamon soil during 16 months of incubation,except in month 8,and out of all the three soils,the lowest reduction in MF was observed in the red soil.From months 16 to 24 of incubation,the reduction rate of MF was the greatest in the black soil for the RS and RS+EB treatments,followed by that in the cinnamon soil.Although the increases in concentrations of WS-Cu and E-Cu were observed in the cinnamon soil under the RS and RS+EB treatments, the decrease in SP/CA-Cu was nearly 30 mg kg-1,which was the largest reduction among the three soils,resulting in the maximum reduction in MF in this soil.

TABLE II Changesa) of Cu mobility factor(MF)values with time(based on data collected every four months)in three typical Chinese soils incubated with different amendments in the presence of exogenous Cu for 24 months

In addition, CA-Cu was sensitive to soil pH. Some organic acids were released during the decomposition of OM, which could dissolve the carbonate in the soil. The decreased pH in the cinnamon soil in the RS and RS+EB treatments also supported the above results(Table SIV,see Supplementary Material for Table SIV).In the two acidic(red and black)soils,small increases in WS-Cu were observed in the RS and RS+EB treatments,while the concentrations of E-Cu and SP/CA-Cu decreased significantly compared to that in the control.Despite a relatively higher MF reduction rate in the black soil in the RS and RS + EB treatments,the black soil showed a much lower decrease in MF than the other two soils owing to its low MF(＜10).

In terms of HA-Cu,the organic amendment treatments indicated no statistically significant difference from the control in the black soil. However, a significant elevation of HA-Cu in the two mineral soils(red and cinnamon soils)was observed in the RS and RS+EB treatments.Fresh carbon inputs may cause a net loss of OC,which is attributed to a“priming effect”(Keiluweitet al.,2015).The priming effect could result in an increase in soil OC levels(Table SV,see Supplementary Material for Table SV),including dissolved OC(Table SVI,see Supplementary Material for Table SVI)and functional groups(–OH-or–COOH-),which are in the stable forms of OM,such as humic substances(Table SVII,see Supplementary Material for Table SVII).Therefore,the influence of OM on Cu mobility is the result of both humic substances and DOM(Zenget al.,2011).Humic substances include many phenolic and carboxyl groups,which can form complexes with Cu ions,reducing the solubility of Cu in the soil solution(Baker and Khalili,2005;Ladoet al.,2008).Using fourier-transform infrared spectroscopy, a previous study found that Cu was bound to OM by forming a covalent Cu-C bond(Golubevaet al.,2013).The CH2and CH3deformation vibrations at 1 470 and 1 350 cm-1and the C=O(carboxyl) stretching or O-H deformation at 1 725 cm-1are attributed to Cu sorption(Chenet al., 2015; Liet al.,2018).Moreover,aliphatic(1 795 cm-1)or aromatic groups(2 370–2 280 cm-1)were not present after Cu sorption,and may have formed Cu bonds(Kanbar and Kaouk,2019).In contrast,an increase in DOM promoted the Cu concentration in the soil solution.From the result that the small reduction of MFs and limited observed changes in Cu species in the black soil under the RS and RS+EB treatments,the decrease in Cu mobility was less influenced by the priming effect in the acidic organic soil(black soil)than by that in the other two soils.However,in the red and cinnamon soils,Cu species are more sensitive to the priming effect,which could cause variations in pH level and OM content.

Time effects ofRS andEB on reduction ofCumobility

The duration of the study was also found to affect Cu mobility(Fig.2).Our data showed that the Cu MF values declined over time during the first 20 months of incubation;and then increased from months 20 to 24 in all the soils under the different treatments.This indicates that Cu mobility does not always decrease over time. However, some previous studies have shown that the mobility of metals declines with time during the aging process(Owsianiaket al.,2015;Li H Yet al.,2016;Li Jet al.,2016),which disagrees with the results of this study.This difference may be related to the reduction of humic substances(Table SVII)and amorphous iron oxides(Table SII)and the increase in iron oxides complexed on the OM in the Cu aging process(Fig.S2,see Supplementary Material for Fig.S2).We also calculated the time effects of the soil amendment treatments on the Cu mobility,with the data showing that the RS and RS+EB treatments accelerated the reduction in Cu MF,compared to the control.In addition,the reduction rates in MF after 16 and 24 months were similar in the red and cinnamon soils,respectively(Table II).In the black soil,the reduction rate of MF was much higher as a result of aging under the RS and RS+EB treatments,than under the control during the initial 20 months of incubation.However, the reduction rates of MF decreased in the last four months of the study, but were still much higher than those in the control.These findings indicate that the effect of organic amendments on reducing Cu mobility could last for 16 and 24 months in the red and cinnamon soils,respectively.In the black soil, the reducing effect of the RS and RS +EB treatments on the Cu mobility could last for more than 24 months.

The variance in MF may be closely related to the mineralization of OM.The black soil had the highest OC content(＞30 g kg-1),while the concentrations of OC were similar in the red and cinnamon soils(＜10 g kg-1).Indeed,Miaoet al.(2017)found that RS was decomposed at lower rates in the organic soil(total OC:159 g kg-1)than in the mineral soil(total OC:17 g kg-1).Therefore,it is likely that the decomposition of OM in the black soil will last longer with the prolonged effect of organic amendments that will reduce Cu mobility.Furthermore,Reducing Cu mobility by organic amendments lasted for a shorter time in the red soil(16 months)than in the cinnamon soil(24 months),which is unexpected because the mineralization rate of OM is higher in neutral-to-alkaline soil than in acidic soil (Zhu, 1996).This may be due to the higher pH values observed in the cinnamon soil than in the red soil.With the application of RS, the reduction rates were the highest after 12, 12, and 8 months of incubation in the red,cinnamon,and black soils,respectively.

In contrast to the RS treatment,the RS+EB treatment did not change the reduction rate of MF. During the RS+ EB treatment of the red soil, a higher reduction rate of Cu mobility was only observed in the first 8 months of incubation, which is inconsistent with our hypothesis.This may be because the EB were not adapted to the soil environment,leading to a decreased ability to immobilize Cu.

CONCLUSIONS

Red,cinnamon,and black soils are distributed worldwide,and RS is a common agricultural waste that is often used in the remediation of soil metals.The increase in OM content in mineral soils might be an important indicator of the immobilization of Cu, and organic soils are superior for Cu fixation.The Cu MF values gradually declined over time during the 20 months of incubation;however,a slight increase in MF was observed after 24 months of incubation. Our results suggest that various soil types should be amended with RS for different durations to achieve a high Cu mobility reduction efficiency during the soil remediation process.This research elucidates the aging and time effects of organic amendments on the distribution and mobility of Cu.The properties and amounts of organic amendments will change in the soil,which will have a direct influence on the mobility of Cu.Therefore,future studies should focus on the adsorption mechanism of organic amendments on Cu under long-term remediation.

ACKNOWLEDGEMENTS

This study was supported by the National Key R&D Program of China(No.2019YFC1605600),the National Natural Science Foundation of China(No.32072662),the National Youth Natural Science Foundation(No.4180071811),the Natural Science Foundation of Guangdong Province,China(No. 2020A1515010819), the Doctor-Initiated Project of the Public Monitoring Center for Agro-Product of Guangdong Academy of Agricultural Sciences,China(No.ZXRC-201903),the President Foundation of Guangdong Academy of Agricultural Sciences,China(No.202017),the Special Found for Scientific Innovation Strategy-Construction of High Level Academy of Agriculture Science, China (No.R2021YJ-QG006),and the Foundation Project of Director of Institute of Quality Standard and Monitoring Technology for Agro-Products of Guangdong Academy of Agricultural Sciences,China(No.DWJJ-202113).

SUPPLEMENTARY MATERIAL

Supplementary material for this article can be found in the online version.