Nutrient Uptake of Ornamental Plants Exposed to Arsenic in Hydroponic Solution

Transcription

1 Journl of Agriulturl Siene; Vol. 5, No. 12; 2013 ISSN E-ISSN Pulished y Cndin Center of Siene nd Edution Nutrient Uptke of Ornmentl Plnts Exposed to Arseni in Hydroponi Solution Stewrt Reed 1, Toms Ayl-Silv 1, Christopher B. Dunn 1, Grry G. Gordon 2 & Aln Meerow 1 1 USDA, Agriulturl Reserh Servie, Sutropil Hortiulture Reserh Sttion, Old Cutler Rod, Mimi, FL 33158, USA 2 Deprtment of Homelnd Seurity, U.S. Customs nd Border Protetion, Mimi Crgo Clerne Center, 6601 NW 25 TH Street Room 272, Mimi, FL 33122, USA Correspondene: Stewrt Reed, USDA, Agriulturl Reserh Servie, Sutropil Hortiulture Reserh Sttion, Old Cutler Rod, Mimi, FL, USA. Tel: E-mil: stewrt.reed@rs.usd.gov Reeived: August 14, 2013 Aepted: Septemer 5, 2013 Online Pulished: Novemer 15, 2013 doi: /js.v5n12p1 URL: Astrt Arseni-sed gro-hemils hve ontminted oiderle rege on turf-frms, orhrds, nd round hortiulturl prodution strutures. A study ws undertken to evlute iris (Iris svnnrum), swithgrss (Pnium virgtum), Tithoni rotundiflor, Coreopsis lneolt, sunflower (Helinthus nnuus), nd mrigold (Tgetes eret) for their potentil use s rseni (As) umultor plnts. Plnts were grown hydroponilly with modified Hoglnd solution ontining either 0, 10, 50 or 70 um As (,,, mg L -1, respetively). At mg As L -1 solution there were no signifint redutio in dry weight elow tht of the ontrols for iris mrigold nd sunflower. Mximum shoot As ontent (mg) for oreopsis nd tithoni ws rehed t nd for swithgrss t mg As L -1 solution. Iris mrigold nd sunflower mximum shoot As levels ourred t solution onentrtion ove mg As L -1 solution, the high level used in this study. In generl P deresed nd S inresed with inresing solution As. Mrigold, swithgrss nd sunflower, speies tht tolerted As t the levels used in this study, hd wek negtive orreltion etween As nd Cu onentrtio in ommon. In these speies As in hydroponi solution hd no effet, or even slightly enhned, P uptke ompred to ontrols. Arseni seitive speies oreopsis nd tithoni hd wek negtive orreltio etween As nd K nd P in ommon. Coreopsis nd tithoni ppers to hve ompetitive uptke mehnism etween rsente with phosphte. Arseni tolerne in iris ppers to e result of prohiiting As umultion in root tissue. 1. Introdution Arseni-sed pestiides, heriides nd ietiides hve ontminted lrge mount of rege on turf-frms, orhrds, nd round greenhouses, shdehouses nd other hortiulturl prodution strutures (Woolson Axley, & Kerney, 1971; Murphy & Auott, 1998). Nturlly ourring soil As n rnge from 1-40 mg As kg -1 soil (Wlsh Sumner, & Keeney, 1977), however, ontminted levels n reh s high s 2600 mg As kg -1 soil (Mehrg Nylor, & Mnir, 1994). Arseni is not n essentil element for plnt nutrition (Mrin Mssheleyn, & Ptrik, 1993) nd onduts no known metoli funtion. Plnts vry in their ility to tolerte As (Mehrg, 1994). Toxiity threshold levels rnge from 5 to 100 mg As kg -1 dry weight for most plnts (Kt-Pendis & Pendis, 1992). At low onentrtio As in the oxidized form, rsente, n t s n nlogue of phosphte (Mehrg et l., 1994; Zho M, Mehrg, & MGrth, 2009) nd my ompete with P for uptke y high-ffinity phosphte trporters in root ells (Asher & Rey, 1979; Ullrih-Eerius, Snz, & Novky, 1989; Bleeker, Sht, Vooijs, Verkleij & Ert, 2003). Arsenite, the redued form of As, is likely tken up y quporin hnnels in plnt roots (Mehrg & Jrdine, 2003). One tken up y the roots, plnts tht umulte As in oveground tissue must detoxify it. Rie (Oryz stiv, L.) (Mrin, Mssheleyn, & Ptrik, 1992; M et l., 2008), uumer (Cuumis stivus L.) (Mihuz et l., 2005), Brssi june (Pikering et l., 2000), tomto (Lyopersium esulentum) (Burló Guijrro, Cronell-Brrhin, Vlero, & Mrtinez-S nhez, 1999), Sprtin pte nd Sprtin lterniflor (Cronell-Brrhin, Ari, DeLune, Gmrell, & Ptrik, 1998), redue rsente to rsenite in the root, however, very little As is trloted from root to shoot. 1

2 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 Plnts tht umulte As t rte >1000 ug As g -1 plnt dry weight re known s hyperumultors (Mhdo-Estrd Clderón, Moreno-Sánhez & Rodríguez-Zvl, 2012). These plnts trlote lrge portion of As to the shoot. Brke fern (Pteris vittt) found growing on n As ontminted site in Florid ws the first rseni hyperumultor desried in the literture (M et l., 2001). M reported tht rke fern fronds growing in 1500 mg kg -1 As ontminted soil umulted up to ug As g -1 plnt dry weight over two week growing period. Sine tht time severl fern speies hve een identified s As-hyperumultors: Pteris reti, Pteris longifoli, Pteris vittt nd Pteris umros (Zho, Dunhm, & MGrth, 2002) nd Pityrogrmm lmelnos (Visoottiviseth et l., 2002). However, not ll fer hve the ility to hyperumulte As. Mehrg (2003) reported tht Pteris strmine nd Pteris tremul did not hyperumulte As in their fronds. The As hyperumultor Pteris vittt shipped 8 x more As from root to shoot thn the nonhyperumultor Pteris tremul (Cille, Zho, & MGrth, 2005) nd 2.8 x more thn Pteris eiformis (Singh & M, 2006). A vriety of speies, other thn fer, hve een identified tht hyperumulte or re tolernt to high levels of As. Ari et l. (2013) reported tht t 50 um As, mustrd shoots (Brssi june L.) ontined from 1.84 to 3.65 mg As g -1 dry weight. Arseni umultion ws reported y Cstillo-Mihel et l. (2009) in Chilopsis lineris (Desert willow), y Bleeker et l. (2003) in the flowering plnt Cytisus stritus, nd y Krimi, Ghderin, R, Feldmnn, nd Mehrg (2009) in rssi, Istis pdoi. The disovery of plnts tht hyperumulte As hs renewed n interest in phytoremedition to tret ontminted sites. An idel plnt for phytoremedition would hve vigorous growth to help prevent As from moving off site through erosion. It should tke-up nd store As in ove ground plnt prts for eventul hrvest. Plnts defined s As hyperumultors hve Bioumultion Ftor (BF) > 1000 ug As g -1 plnt dry weight (Mhdo-Estrd et l., 2012). They hve n As shoot-to-root rtio (Trlotion Ftor (TF)) > 1. It hs een found tht plnts with BF > 1 n e useful in phytoremedition if they store most of their As in the shoot leding to TF >1 (MGrth & Zho, 2003). Ornmentl plnts hve not een fully investigted s mehnism for phytoremedition of As ontminted soil. Ornmentls n prtilly offset the ost of lnd tken out of prodution through the sle of ut flowers nd other mrketle ommodities. In ddition, these plnts n provide n estheti qulity to uildings loted on ontminted sites. The Florid Deprtment of Environmentl Protetion gols for lenup of residentil nd industril soils re 0.8 nd 3.7 mg As kg -1 soil, respetively. On 14 South Florid golf ourses ssoited with high groundwter As onentrtio, n verge As onentrtion of 13.7 mg kg -1 ws found in the fine ly frtion (Ci, Crer, Georgidis, & Jyhndrn, 2002). This indites possile impt from pplitio of rseni-ontining heriides. In urn soils from Ginesville nd Mimi, Florid, rnge of 0.21 to 660 mg As kg -1 soil ws found (Chirenje et l., 2003). In the Mimi soils 95% of these smples exeeded the Florid residentil gol nd 33% exeeded the ommeril gol. Soil ontminted with As levels ove regultory gols is prolem in South Florid. The purpose of this study ws to evlute nutrient uptke y ornmentl plnts grown in hydroponi system ontining As. 2. Mterils nd Methods 2.1 Plnt Speies Iris (Iris svnnrum), swithgrss (Pnium virgtum), Tithoni rotundiflor, Coreopsis lneolt, sunflower (Helinthus nnuus), nd mrigold (Tgetes eret) were used in this study. A 25% perlite, 37% pine rk, 8% snd, 30% oir potting mixture ws used for ll plnts exept iris. Ten m iris rhizomes, olleted from single plnt were set in rokwool to help mintin rhizome orienttion during e nd flow yles in the hydroponi system. Swithgrss seed ws evenly sowed in 28x53 m trys. One plnts rehed 10 m in height, 30, 18-m setio of turf were utout nd pled into 26-m dimeter pots (3.8 L). Swithgrss ws trimmed to uniform 15 m height efore tretments egn. Tithoni, sunflower nd mrigold seedling with t lest two fully developed leves nd iris nd oreopsis 10 m tll with 3 leves were pled in 26-m pots. The study ws onduted over three different time periods with two plnt speies growing during eh period. Dtes for eh time period re given in Tle 1. 2

3 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 Tle 1. Plnting, initition of rseni tretments nd hrvest dtes for six plnt speies: iris, swithgrss (Pnium virgtum), Tithoni rotundiflor, Coreopsis lneolt, sunflower (Helinthus nnuus) nd mrigold (Tgetes eret) Speies Plnting Tretment Hrvest Iris svnnrum 21-De Mr My-10 Swithgrss (Pnium virgtum) 21-De Mr My-10 Tithoni rotundiflor 6-Ot Ot Nov-10 Coreopsis lneolt 6-Ot Ot Nov-10 Sunflower (Helinthus nnuus) 1-Fe Fe Mr-11 Mrigold (Tgetes eret) 1-Fe Fe Mr Hydroponi System Six e-nd-flow type hydroponi plnt mintenne systems were used for the study. Eh system ontined 208 L reservoir tnk filled with 132 L wter. Eh tnk ws onneted to 12, 3.8-L pots. A timer llowed the system to yle etween 30 min. wet nd 4 hr. drin periods, eginning t 8 A.M., ending t 4 P.M. followed y 12 hr. drin period. A modified Hoglnd solution ws used to supply plnt nutrients. Nutrients were dded in the form of onentrted stok solutio efore tnks were rought to their finl volume. Finl nutrient onentrtio in eh tnk were 2.0 mm C(NO 3 ) 2, 3 mm KNO 3, 1.0 mm MgSO 4, 0.25 mm C(H 2 PO 4 ) 2, 12.5 um H 3 BO 3, 1.0 um MnSO 4, 1.0 um ZnSO 4, 0.25 um CuSO 4, 0.2 um (NH 4 ) 6 Mo 7 O 24, nd 10 um Fe-EDDHA. Tp wter used to mix nutrient solutio verged 028 mg L -1 As (0.448 mg per reservoir tnk). Plnts limted to hydroponi feeding for minimum of one week efore eginning As tretments. Enough N 2 HAsO 4, dissolved in 1.0 L wter, ws dded to different reservoirs to mke finl tnk onentrtion of 0, 10, 50 or 70 um As (,,, mg L -1 As, respetively). An As solution onentrtion of 2-8 um equtes to soil As onentrtion of mg kg -1 (Moreno-Jiménez, Esten, Fresno, López de Ege, & Peñlos, 2010). Bsed on this nd the levels of ontminted urn soils reported ove, rnge of um As solution onentrtion ws seleted to over the rnge of low level As ontmintion found in south Florid s urn soils. Reservoir ph ws djusted dily to ph 6.5 with either NOH or H 2 SO 4. Nutrient nd As solutio were repled weekly. Plnts were mintined in hydroponi solution until flowering. 2.3 Smple Anlysis Shoot nd root tissue were hrvested seprtely. Roots were gitted in pool of wter then wshed with gentle spry. Shoot nd root tissue were oven dried t 45 C until there ws no longer weight hnge with dditionl drying nd the dry weights reorded. Dried tissue ws stored for nlysis. An uptke rtio UR = mg As kg -1 plnt dry weight/solution onentrtion in mg As L -1 solution (1) nd trlotion ftor TF = shoot As / root As in mg As kg -1 plnt dry weight (2) were lulted for eh speies nd eh tretment. Approximtely 0.25 g of oven dried plnt tissue ws pled in 100-mL digestion tues. Ten ml HNO 3 ws dded nd smples digested in mirowve digestion system for 15 min to reh 200 C then kept t this temperture for n dditionl 15 min. Digests were diluted to 100 ml nd stored t 4 C prior to nlysis. Element onentrtio were determined y indutively oupled plsm optil emission spetrometry with n icap 6300 Duo View (ThermoFisher Sientifi, West Plm Beh, Florid). Dt were nlyzed nd onentrtio determined using ThermoFisher Sientifi icap 6300 iteva softwre. 2.4 Sttistil Anlysis Eh plnt speies ws nlyzed seprtely. The dt represent me lulted from six replited pots for eh As tretment. Anlysis of vrine ws preformed using the Pro Mixed proedure of Sttistil Anlysis System (SAS It., 1999). Tukey djusted lsme were used for omprison t P < 5 unless stted otherwise. Arithmeti me were used to lulte uptke rtio nd trlotion ftor. 3

4 Journl of Agriulturl Siene Vol. 5, No. 12; Results 3.1 Generl Comments Results for plnt growth nd As uptke were reported in Reed, Ayl-Silv, Dunn, Gordon, nd Meerow (2013). In summry, sed on dry weight, tithoni nd oreopsis did not produe enough iomss to merit oidertion for ioremedition. Mrigold nd sunflower hd uptke rtios of 7.4 nd 16.6, respetively, nd trlotion ftors ner one. Both show little effet of As toxiity on dry weight prodution t solution onentrtio of mg As L -1, therefore, re ppeling ndidtes for phytoremedition nd phytostiliztion. Swithgrss nd iris n e hrvested multiple times yer, mking them ndidtes for phytostiliztion. In the urrent report. there were signifint differenes t P 5 etween As tretments nd etween shoot nd root tissue As onentrtion in ll plnt speies. In most speies, dry weights deresed with inresing solution As, however, iris nd mrigold did not follow this trend. Arseni uptke inresed with suessive hrvests in swithgrss. 3.2 Dry Weight Differenes in root dry weight from the As ontrol to mg As L -1 tretment were smll or not signifint in iris, mrigold nd sunflower (Figure 1). Signifint differenes in root dry weight ppered t mg As L -1 solution in swithgrss. Even t the high solution As rte, swithgrss produed high root dry weight, n importnt oidertion in seletion of speies pproprite for limiting erosion of ontminted mteril. Redutio in root dry weight from toxi onentrtio of As ffeted tithoni t the lowest onentrtion ( As mg L -1 ) nd oreopsis t mg As L -1. Tithoni nd oreopsis exhiited similr seitivity to As with shoot dry weight (Figure 2) Root dry weight (mg) Coreopsis Iris Mrigold SunflowerSwithgrss Tithoni Plnt speies Figure 1. Root dry weight (mg) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level Tretment differenes from the ontrol in shoot dry weight for iris, mrigold nd sunflower were either non-signifint or very smll (Figure 2). Both iris nd mrigold hd slight tendeny to inrese dry weight with inresing solution As up to mg L -1. Other reserhers hve reported similr findings t low As onentrtio with potto (Solnum tuerosum L.) (Jos, Keeney, & Wlsh, 1970), mize (Woolson et l., 1971), rie (Mrin et l., 1992), Sprtin pte nd S. lterniflor (Cronell-Brrhin et l., 1998), nd Jpnese mustrd spinh (Brssi rp L. vr. pervirdis) (Shiur & Kwi, 2009). Signifint redutio in swithgrss shoot dry weight egn t the lowest level of solution As (Figure 2). However, despite deresing dry weight prodution with inresing exposure to As, swithgrss growth remined 4

5 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 reltively vigorous. During this study, swithgrss ws hrvested three times nd with eh suessive hrvest dry weights inresed. Wrmer spring tempertures possily influened this inrese in growth. After 76 d the ontrol nd high As treted plnts inresed dry weight t rte of 0.22 nd 0.19 m d -1, respetively. At finl hrvest, 121 d, dry weight inresed t rte of 2.4 nd 0.74 m d -1 for ontrol nd high As tretment, respetively. 100 Shoot dry weight (mg) Coreopsis Iris Mrigold SunflowerSwithgrss Tithoni Plnt speies Figure 2. Shoot dry weight (mg) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level 3.3 Tissue Arseni Conentrtion Root As ws oistently higher thn shoot As onentrtion for ll speies t ll solution As levels (Figures 3 & 4). Figure 3 presents As onentrtion in root tissue. Coreopsis umulted the lrgest root tissue As onentrtion of the speies studied. There ws lrge inrese in root As onentrtion etween the mg L -1 tretment nd higher solution As tretments (Figure 3). Totl root As uptke did not vry muh, rnging from 0.3 to 0.4 mg As t nd mg L -1 solution As, respetively. Given totl As ontent ws similr in ll tretments, the inrese in root As onentrtion mostly ws the result of delining root dry weight with inresed exposure to As (Figure 1). Shoot As onentrtion inresed nd dry weight deresed with n inrese in solution As (Figure 4). A similr pttern of lrge dereses in root nd shoot dry weight ontrolling As onentrtion ws oserved with tithoni. Mrigold, sunflower nd to lesser extent swithgrss hd reltively low dereses in root nd shoot dry weights with inresed exposure to As (Figures 1 & 2) nd umultion of As in root nd shoot tissue drove inreses in As onentrtion (Figure 3 nd 4). At mg L -1 solution As, sunflower quired the seond lrgest root As onentrtion ehind oreopsis (Figure 3). However, oth oreopsis nd sunflower produed omprtively little root dry mtter (Figure 1). At mg As L -1 tithoni hd the highest shoot As onentrtion followed y sunflower, oreopsis, iris, mrigold, then swithgrss (Figure 4). Arseni onentrtion in iris root tissue ws very low, even t the high solution As rte (Figure 3). Only 6 mg totl As ws found in iris root nd rhizome tissue. Despite wide rnge in shoot As onentrtion there were no signifint differenes etween the tretments nd As ontrol (Figure 4). 5

6 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 As onentrtion (mg kg -1 ) oreopsis iris mrigold sunflower swithgrss tithoni Plnt speies Figure 3. Root rseni onentrtion (mg As kg -1 dry weight) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level As onentrtion (mg kg -1 ) oreopsis iris mrigold sunflower swithgrss tithoni Plnt speies Figure 4. Shoot rseni onentrtion (mg As kg -1 dry weight) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level 6

7 Journl of Agriulturl Siene Vol. 5, No. 12; Totl Shoot As Figure 5 shows the mg As in shoot tissue for eh speies for eh tretment. The mximum shoot As ontent in oreopsis, nd tithoni ourred t mg L -1. Mrigold followed y sunflower ontined the gretest mount of shoot As fter 50 d growth t 0.85 nd 0.56 mg As, respetively. Shoot As inresed with inresing solution As onentrtion with the onentrtion for optimum removl ove mg L -1, the highest As onentrtion used in this study. Both speies produed flowers in ll tretments. Iris, grown for 160 d, did not reh its optimum As removl ut ontined less thn hlf the totl shoot ontent of sunflower. Swithgrss (160 d) hd n optimum removl ner mg L -1 representing As olleted from two uttings. Both swithgrss nd iris plnts n e repetedly ut nd new growth ours. Additionl hrvests ould sustntilly inrese the mount of As removed. The uptke rtio nd trlotion ftor t mg As L -1 solution for eh speies is s follows: oreopsis 73.0 nd 7, tithoni 33.4 nd 1.13, sunflower 16.6 nd 0.88, iris 6.7 nd 9.21, mrigold 7.4 nd 1.20, nd swithgrss 1.5 nd 0.16 (Reed, Ayl-Silv, Dunn, Gordon, & Meerow, 2013). Shoot As (mg) Coreopsis Iris Mrigold SunflowerSwithgrss Tithoni Plnt speies Figure 5. Shoot rseni (mg) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level 3.5 Arseni nd Plnt Nutrition Person Correltion Coeffiients for plnt As onentrtion mthed with seleted plnt nutrient element onentrtion reveled no oistent trends mong the different speies. For exmple in iris, hnges in plnt As onentrtion were not relted to hnges in ny plnt nion or tion nutrient, wheres, As hd wek to moderte positive orreltion with Fe in oreopsis nd mrigold nd wek negtive orreltion in tithoni (Tle 2). There were few signifint orreltio etween As nd either P or S ut in generl P deresed nd S inresed with inresing As. Mrigold, swithgrss nd sunflower, speies tht tolerted As t the levels used in this study, hd only wek negtive orreltion etween As nd Cu onentrtio in ommon. Arseni seitive speies oreopsis nd tithoni hd wek negtive orreltio etween As nd K nd P in ommon. Totl nutrient element ontent (mg) is given in Tle 3. In generl oreopsis element ontent t mg As L -1 solution ws lower thn tht found in the ontrol. Sulfur ontent inresed t mg L -1 As solution onentrtion nd egn to deline therefter. At mg L -1 solution As, plnt dry weight redution from As toxiity ws not yet pprent. The sme trend held for swithgrss nd sunflower, lthough in sunflower differenes were mostly non-signifint. An inrese in swithgrss S ontent ws found t solution As tretments up to mg L -1. In iris, nutrient element ontent ws greter t mg As L -1 thn in the ontrol. An inrese in S ontent did not pper until mg L -1 solution As. In mrigold, there were few sttistil differenes in element ontent etween the ontrol nd high As level. Signifintly lower element ontent in tithoni first ppered t the lowest ( mg L -1 ) solution As onentrtion for ll elements exept B nd P. Also, tithoni hd signifint drop in dry weight etween the ontrol nd lowest As tretment. 7

8 Journl of Agriulturl Siene Vol. 5, No. 12; Plnt P There were no signifint As differenes etween the ontrol nd As tretments in root P onentrtion for oreopsis, iris nd mrigold (Figure 6). In swithgrss, root P ws lowered t the high rte only. With sunflower, the nd mg As L -1 tretments hd higher root nd shoot P thn the ontrol (Figure 6 & 7). Root nd shoot P deresed with inresing solution As in tithoni. Shoot P ws similr in ll As tretments nd ontrol for oreopsis, mrigold nd swithgrss (Figure 7) nd in iris, only the mg As L -1 tretment hd lower shoot P onentrtion thn the ontrol. Tithoni ws the only speies where solution As ove mg L -1 ppered to signifintly redue P uptke elow tht of the ontrol. Adequte P ws supplied in the nutrient solution nd As onentrtio used were pprently not high enough to overwhelm P uptke. The lk of onnetion etween As vilility in the growing medium nd tissue P is in greement with Mehrg nd Mnir (1992) who reported, inresed plnt phosphte sttus led to redued rsente influx. Tle 2. Correltion oeffiient nd P vlue for As tissue onentrtion with seleted elements for Coreopsis lneolt, iris, mrigold (Tgetes eret), sunflower (Helinthus nnuus), swithgrss (Pnium virgtum) nd Tithoni rotundiflor Coreopsis lneolt B C Cu Fe K Mg Mn Mo P S Zn As * * * * *** * Iris svnnrum B C Cu Fe K Mg Mn Mo P S Zn As * Mrigold (Tgetes eret) B C Cu Fe K Mg Mn Mo P S Zn As * * * * Sunflower (Helinthus nnuus) B C Cu Fe K Mg Mn Mo P S Zn As * * * * Swithgrss (Pnium virgtum) B C Cu Fe K Mg Mn Mo P S Zn As * * ** Tithoni rotundiflor B C Cu Fe K Mg Mn Mo P S Zn As * * *** * * * P 0.1, > 1, ** P 1, > 01, ** P 01. 8

9 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 Tle 3. The effet of solution As onentrtion (mg As L -1 solution) on element ontent (mg pot -1 ) in plnt tissue for Coreopsis lneolt, iris, mrigold (Tgetes eret) sunflower (Helinthus nnuus), swithgrss (Pnium virgtum) nd Tithoni rotundiflor mg As L -1 solution As B C Cu Fe K Mg Mn Mo P S Zn Coreopsis lneolt SE Iris svnnrum SE Tgetes eret (mrigold) SE Helinthus nnuus (sunflower) SE Pnium virgtum (swithgrss) d SE Tithoni rotundiflor SE Vlues followed y the sme letter re not signifintly different t P < 5. Iuffiient tissue ws ville for inlusion in sttistil nlysis. Vlues given re omposite from one root nd two shoot smples. 9

10 Journl of Agriulturl Siene Vol. 5, No. 12; P onentrtion (mg P kg -1 dry weight) Coreopsis Iris Mrigold Sunflower Swithgrss Tithoni Plnt speies Figure 6. Root phosphorus onentrtion (mg P kg -1 dry weight) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level P onentrtion (mg P kg -1 dry weight) Coreopsis Iris Mrigold Sunflower Swithgrss Tithoni Plnt speies Figure 7. Shoot phosphorus onentrtion (mg P kg -1 dry weight) from plnts grown in,,, or mg As L -1 solution onentrtion. Brs represent lest squres me estimte with stndrd error. For eh speies similr letters top rs indites no signifint differene y Tukey-Krmer t P 5 level 4. Disussion Arsente uptke y plnts n e oidered n nlogue of phosphte in tht they shre the sme trport pthwy (Mehrg et l., 1994). At low soil P mehnism with high ffinity for phosphte opertes nd ompetition from As for uptke sites is wek (Mehrg & Mnir, 1992). As soil P levels inrese this system 10

11 Journl of Agriulturl Siene Vol. 5, No. 12; 2013 eomes inresingly intive. One rsente is tken up y root ells, smll mount my e trported to the xylem ut the mjority is redued to rsenite (Zho et l., 2009). Arsenite is either exported k into soil, trported in the xylem to stem nd leves, or omplexed with n orgni ompound for storge in vuole. Arseni non-hyperumultors tend to store most of the rsenite in the root with little trported to stem or lef tissue. All plnts used in this study were As non-hyperumultors, however, there were different ptter in As umultion, tolerne/voidne mong the plnt speies. Only smll mount of As ws found in iris root nd shoot tissue. Inresing solution As hd little ffet of tissue P onentrtion. In iris, either root ells were very effiient t As efflux k into soil or As did not ompete effetively with P for uptke sites. Arseni tolerne in iris ppers to e result of prohiiting ny umultion in root tissue. Bsed on redution in dry weight, tithoni ws most seitive to As exposure with n 85% redution in weight t the lowest ( mg As L -1 ) solution onentrtion. Root nd shoot As onentrtio were roughly equl nd As ppered to redue P uptke. In this study the highest solution As onentrtion ws 70 μm ( mg L -1 ). Bldwin nd Buther (2007) reported signifint differenes in tissue P onentrtion with Pteris reti (Moonlight fern) plnts etween zero As ontrols nd plnts exposed to 500 μm rseni. This oservtion held for root, stem, nd lef tissue. Pteris reti is n As hyperumultor where As ws seletively umulted in stem nd root tissue. Cstillo-Mihel et l. (2009) reported similr results with Chilopsis lineris (Desert willow) suggesting ompetition etween rsente with phosphte for rriers in the plsm memrne. Coreopsis nd tithoni ppers to hve similr ompetitive uptke mehnism. In mrigold nd swithgrss there were no differenes etween ontrols nd As tretments for root nd shoot P. Sunflower nd mg L -1 As tretments hd higher root nd shoot P thn ontrols. Arseni in root tissue inresed with inresing solution As in these speies. An As onentrtion less thn 9% of tht in root tissue ws found in shoots of mrigold, swithgrss nd sunflower. The presene of As in hydroponi solution hd no effet, or even slightly enhned, P uptke ompred to ontrols. There were no differenes in root or shoot P onentrtion in mrigold nd only t the high As rte in iris ws there redution in shoot P onentrtion elow tht of the ontrol. Although there were no sttistil differenes etween the high As rte nd the ontrol, seondry nd mironutrient ontents ll generlly inresed with inresing solution As onentrtion. Improved minerl nutrition t mg L -1 As ould ount for the higher dry weights in iris nd mrigold. 5. Conlusio Bsed on rpid redution in dry weight with exposure to As, oreopsis nd tithoni were plnts tht proved to e very seitive to As. Totl As in plnt tissue rehed high levels even t low solution As onentrtio. Plnt nutrient uptke delined with inresing solution As onentrtion. Iris took up very little As t the two lower solution onentrtio nd dry weights tully inresed. This resulted in either no differene or n inrese in nutrient uptke. In ontrst with iris, swithgrss redily took up As. There ws derese in dry weight ut even t the high solution As onentrtion high mount of iomss ws produed. There ws deline in plnt nutrient ontent with inresing tissue As. In mrigold nd sunflower there were no differenes in nutrient ontent with inresing tissue As up to the highest solution onentrtion used in this study. Iris, swithgrss, sunflower nd mrigold, ndidtes for phytostiliztion or phytoremedition mintined dequte plnt nutrient uptke t solution As onentrtion of t lest mg L -1. Referenes Ari, M. K. A., Sho, H. B., Umr, S., Ahmd, A., Ari, S. H., Iql, M., & Owe, G. (2013). Sreening Indin mustrd genotypes for phytoremediting rseni-ontminted soils. Clen Soil, Air, Wter, 41, Asher D. J., & Rey, P. F. (1979). Arseni uptke y rley seedlings. Journl of Plnt Physiology, 6, Bldwin, P. R., & Buther, D. J. (2007). Phytoremedition of rseni y two hyperumultors in hydroponi environment. Mirohemil Journl, 85, Bleeker, P. M., Sht, H., Vooijs, R., Verkleij, J. A. C., & Ert, W. H. O. (2003). Mehnisms of rsente tolerne in Cytisus stritus. New Phytologist, 157,

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