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2 Aquti Botny 1 (212) 35 4 Contents lists ville t SiVerse SieneDiret Aquti Botny j ourn l ho me pge: Effets of flooding nd sedimenttion on the growth nd physiology of two emergent mrophytes from Dongting Lke wetlnds Ying Pn,,, Yonghong Xie,,, Xinsheng Chen,, Feng Li, Key Lortory of Agro-eologil Proesses in Sutropil Region, Institute of Sutropil Agriulture, Chinese Ademy of Sienes, Hunn, 41125, Chin Dongting Lke Sttion for Wetlnd Eosystem Reserh, Institute of Sutropil Agriulture, The Chinese Ademy of Sienes, Chngsh 41125, Chin Grdute Shool of the Chinese Ademy of Sienes, Beijing 149, Chin r t i l e i n f o Artile history: Reeived 7 Septemer 211 Reeived in revised form 2 Mrh 212 Aepted 6 Mrh 212 Aville online 17 Mrh 212 Keywords: ADH tivity Crohydrte Intertion Sediment uril Wter level s t r t The im of this study is to investigte the intertion etween flooding nd sedimenttion on the performne of wetlnd mrophytes. Growth, iomss llotion, lohol dehydrogense (ADH) tivity nd non-struturl rohydrte ontent of the flooding-tolernt speies reviuspis C.B Clrke nd the flooding-intolernt speies Misnthus shriflorus (Mxim.) Hkel from the Dongting Lke wetlnds were investigted experimentlly using two wter levels ( nd 4 m, reltive to the soil surfe) nd three uril depths (, 5 nd 1 m). Biomss umultion nd reltive growth rte (RGR) of oth speies were signifintly inhiited y either higher wter level or deeper uril, exept for C. reviuspis in the 5 m uril depth + m wter level tretment, suggesting tht shllower uril would stimulte the growth of C. reviuspis. Biomss llotion of oth speies ws ffeted y wter level lone, nd more iomss ws lloted to leves t the 4 m wter level. ADH tivity nd solule sugr ontent of C. reviuspis were higher, ut solule sugr nd strh ontents of M. shriflorus were lower in the 4 m thn in the m wter level tretments. Biomss umultion, RGR nd strh ontent of oth speies were unffeted y uril depth t the 4 m wter level. These results suggest tht deeper uril only inhiits plnt growth without flooding, nd tht oth speies n limte to flooding nd/or sedimenttion through djustments of iomss llotion nd rohydrte metolism. 212 Elsevier B.V. All rights reserved. 1. Introdution Flooding nd sedimenttion re mjor stresses limiting plnt growth nd distriution in wetlnd eosystems (Lowe et l., 21), minly through reduing oxygen vilility in root zones (Little nd Mun, 1996; Ferreir et l., 29). Wetlnd plnts n limte to neroi stress minly through series of morphologil nd physiologil djustments, suh s shoot elongtion, higher shoot:root rtio, shllower root system, s well s higher lohol dehydrogense (ADH) tivity nd solule sugr ontent (Little nd Mun, 1996; Chen et l., 25; Sun et l., 21). Although mny studies hve een performed on the effet of flooding or sedimenttion on plnt growth, morphology nd physiology, less ttention hs een pid to the intertive effets of the two stresses (Wlls et l., 25). The intertion pttern etween the two stresses is not onsistent nd my differ mong speies (Wlls et l., 25; Lowe Corresponding uthor t: Institute of Sutropil Agriulture, The Chinese Ademy of Sienes, Chngsh, Hunn 41125, Chin. Tel.: ; fx: E-mil ddress: yonghongxie@163.om (Y. Xie). et l., 21). The proesses of sediment trnsporttion nd deposition re strongly ssoited with flooding, inditing tht flooding might ply more tive role in regulting plnt growth nd distriution ompred to sedimenttion in wetlnd eosystems (Piere nd King, 27). A study y Lenssen et l. (23) hs found tht oth wterlogging nd shde ply importnt roles in inhiiting the growth of two wterlogging-tolernt speies, while wterlogging hs lrger impt on the growth of wterlogging-intolernt speies thn does shde. Therefore, the intertions etween sedimenttion nd flooding on plnt growth might lso e different due to the differene in flooding tolerne mong speies. Dongting Lke, the seond lrgest freshwter lke nd the most typil river-onneted lke in Chin, is usully flooded from My to Otoer, when lrge mount of sediment is deposited nnully (Zheng et l., 29). The purpose of this study ws to investigte the intertion etween flooding nd sedimenttion on the performne of wetlnd mrophytes. To this end, young rmets of two emergent mrophytes ommon to the Dongting Lke wetlnds, the flooding-tolernt speies reviuspis C.B Clrke nd the flooding-intolernt speies Misnthus shriflorus (Mxim.) Hkel (Qin et l., 21), were hosen to grow in two wter levels nd on three uril depths, nd the morphology nd physiology were investigted. C. reviuspis usully ours t the low elevtion /$ see front mtter 212 Elsevier B.V. All rights reserved. doi:1.116/j.quot

3 36 Y. Pn et l. / Aquti Botny 1 (212) 35 4 nd M. shriflorus t the high elevtion. The following hypotheses were tested. Firstly, the growth will e inhiited y oth higher wter level nd deeper uril for flooding-tolernt speies C. reviuspis, ut plnt growth is inhiited y higher wter level lone for the flooding-intolernt speies M. shriflorus. Seondly, oth higher wter level nd deeper uril will led to higher shoot mss rtio, ADH tivity nd solule sugr ontent, nd lower strh ontent for C. reviuspis, nd these responses will e oserved in the environments of higher wter level rther thn deeper uril for M. shriflorus. 2. Mterils nd methods 2.1. Plnt mterils Plnt frgments of C. reviuspis nd M. shriflorus were exvted from stnds in the Chunfeng Villge (N , E ), in the Est Dongting Lke in Mrh 29, respetively. Plnt frgments with roots were pled in seprte plsti ukets, whih ontined 15 m soil (ontining 19 g kg 1 orgni mtter, 29 g g 1 exhngele N, nd 19 g g 1 exhngele P), exvted from the ommunity of C. reviuspis in the Junshn, in the Est Dongting Lke, to germinte new rmets. Orgni mtter, exhngele P nd exhngele N were mesured following the methods of Ryment nd Higginson (1992), Stinton et l. (1977) nd Bremner (1965), respetively. The plnts were wtered when neessry, nd pled in net-house, whih ws overed with one lyer of nylon-net nd the light ws out 5% of full sun Experimentl design The experiment ws strted on 25 August 29. A totl of 3 rmets per speies of similr size (5 8 leves, out 2 m in height) were trnsplnted individully in PVC tues (2 m in height, 11 m in dimeter, one rmet per tue). In eh tue, 4 holes (1 m in dimeter) were evenly drilled t 6 m ove the tue ottom. Eh tue ws filled with 6 m soil (the sme soil used for plnt inution). Chen et l. (211) reported tht 9 m uril signifintly deresed the survivl rte of C. reviuspis, so 1 m ws hosen s the mximl depth. A two-wy ftoril design ws pplied in the experiment, whih omined three uril depths (, 5 nd 1 m) with two wter levels ( nd 4 m, reltive to the soil surfe). A totl of six tretments were inluded in this experiment, eh with five replites. A totl of 6 tues were pled into five plsti ukets (88 m 67 m 63 m, six tretments per speies per uket). The tues were rndomly pled in eh uket. One-time uril ws onduted fter trnsplnttion for one week. The soil used for uril ws the sme s plnt inution. Wter level ws reted y pling the tues either in the uket or on 4 m high riks. Wter depth in eh uket ws mintined t 46 m depth. Tp wter (ontining 51.1 g L 1 NH 4 + N, 176 g L 1 NO 3 N nd 52.7 g L 1 PO 4 3+ P, ph = 7.2) ws supplied s needed nd ws ompletely repled every two weeks Hrvest Plnts were hrvested on 11 Novemer 29. After hrvest, the entire root system of eh plnt ws refully exvted nd lened up y tp wter, then rought to lortory for mesurement. Plnts were divided into leves, stems nd roots (inluding rhizomes), nd fresh mss ws reorded (±.1 g). Aout hlf of the fresh roots were used for nlysis of ADH tivity. The remining plnt tissues were oven dried t 8 C for 72 h, then reweighed to lulte wet to dry onversion ftor. Lef mss rtio, stem mss rtio nd root mss rtio were defined s the rtio of lef mss, stem mss, root mss to iomss umultion, respetively. Biomss umultion ws the sum of lef, stem nd root msses. RGR ws lulted using the following equtions: RGR = (In w 2 In w 1 )/(t 2 t 1 ), where w 1 ws the initil dry mss, w 2 the dry mss t hrvest time t 2, nd (t 2 t 1 ) the experimentl time ADH tivity The root system ws seprted nd.1.5 g of fresh root mteril ws immeditely kept in ie, then ssyed (4 C) in 5 ml ssy mixtures (5 mm phosphte uffer ph 7.5, 5 mm MgCl 2, 1 mm phenylmethyl sulfonyl fluoride). Plnt extrts were then entrifuged t 15, rpm for 2 min t 4 C. Finlly, the plnt extrts were mesured using dignosti lohol kits (Nnjing Jinheng Bioengineering Institute, Chin). The results were expressed in enzyme units per milliliter of totl serum protein; 1 U of the enzyme tlyzes the redution of 1 nmol NAD+ per minute t temperture of 37 C Crohydrte nlyses The ontent of non-struturl rohydrte (inluding strh nd solule sugr) ws nlyzed ording to the methodology desried y Yemn nd Willis (1954). Dry root smples were ground to fine powder nd extrted three times using 8% ethnol (v/v). The extrt ws then used for solule sugr nlysis fter ddition of nthrone regent, followed y mesurement of sorne t 63 nm using spetrophotometer. The residue remining fter solule sugrs extrtion ws dried nd extrted using 3% perhlori id nd nlyzed for strh (s gluose equivlent) using the nthrone regent Sttistil nlysis All sttistil nlyses were performed using SPSS13. pkge (SPSS In., USA). We tested the effets of wter level nd uril depth on iomss umultion, RGR, iomss llotion, ADH tivity, solule sugr nd strh ontents y two-wy ANOVA. Multiple omprisons of mens were performed using Tukey s test t the.5 signifine level nd Bonferroni orretion for multiple omprisons ws mde when neessry. Dtes were log 1 - trnsformed if neessry to redue heterogeneity of vrines, nd homogeneity ws tested using Levene s test. 3. Results 3.1. Biomss umultion nd reltive growth rte (RGR) Both wter level nd uril depth signifintly ffeted iomss umultion of oth speies, with signifint intertions (P <.1, Tle 1). At the sme uril depth, higher wter level led to lower iomss umultion in C. reviuspis (P <.5, Fig. 1). However, the effet of uril depth ws dependent on wter level. At the m wter level, deeper uril led to lower iomss umultion of oth speies, exept for C. reviuspis in the 5 m uril tretment, whih ws 1.4 times higher thn tht in the m uril tretment (.95 versus.7 g dry wt plnt 1, P <.5, Fig. 1). This result indited tht shllower uril would stimulte the growth of C. reviuspis without flooding. At the 4 m wter level, iomss umultion of oth speies ws unffeted y uril depth (P >.5, Fig. 1). RGR showed the similr tendeny s iomss umultion, nd ws unffeted y uril depth t the 4 m wter level (Fig. 1). It ws ler tht deeper uril hd negtive effets on plnt growth without flooding, ut hd no effet t higher wter level.

4 Y. Pn et l. / Aquti Botny 1 (212) Tle 1 Summry of two-wy ANOVAs for iomss umultion, reltive growth rte, iomss llotion nd physiologil hrteristis of reviuspis nd Misnthus shrifloru rmets growing on three sedimenttion depths nd in two wter levels. Buril depth (B) Wter-level (W) B W Speies n %SS P-vlues %SS P-vlues %SS P-vlues Biomss umultion (g dry wt plnt 1 ) 5 25%. 59%. 14%. Misnthus 5 23%. 39%. 2%. Reltive growth rte (g g 1 dry wt dy 1 ) 5 22%. 67%. 4%.42 Misnthus 5 16%.6 47%. 11%.25 Root mss rtio (%) 5 4%.543 3%.3 2%.7 Misnthus 5 2%.73 4%.285 2%.762 Lef mss rtio (%) 5 7% %. 1%.79 Misnthus 5 3%.58 35%.1 7%.265 Stem mss rtio (%) Misnthus 5 11%.24 4%.323 4%.613 ADH (U ml 1 g 1 fresh wt) 4 18%. 59%. 18%. Misnthus 4 2% %. 72%. Solule sugr ontent (mg g 1 ) 4 43%. 46%. 2%.216 Misnthus 4 38%. 35%. 7%.53 Strh ontent (mg g 1 ) 4 12%.1 74%. 4%.48 Misnthus 4 2%.49 83%. 1%.597 Biomss umultion (g dry wt plnt -1 ) 1.5 d d m wter level 4 m wter level d Misnthus Misnthus Reltive growth rte (g g -1 dry wt dy -1 ) Buril depth (m) Buril depth (m) Fig. 1. Biomss umultion nd reltive growth rte of reviuspis nd Misnthus shriflorus rmets growing on three sediment uril depths nd in two wter levels. Results re expressed s men ± S.E. (n = 5). Different letters indite signifint differene mong tretments t the.5 signifine level. Fig. 2. Biomss llotion of reviuspis nd Misnthus shriflorus rmets growing on three sediment uril depths nd in two wter levels. Results re expressed s men ± S.E. (n = 5). Different letters indite signifint differene mong tretments t the.5 signifine level.

5 38 Y. Pn et l. / Aquti Botny 1 (212) 35 4 ADH (U ml -1 g -1 fresh wt) e de m wter level 4 m wter level d Misnthus 5 1 Buril depth (m) 5 1 Buril depth (m) Fig. 3. ADH of reviuspis nd Misnthus shriflorus rmets growing on three sediment uril depths nd in two wter levels. Results re expressed s men ± S.E. (n = 4). Different letters indite signifint differene mong tretments t the.5 signifine level Biomss llotion Biomss llotion of oth speies ws only ffeted y wter level (P <.5, Tle 1). For C. reviuspis, higher wter level led to higher lef mss rtio nd lower root mss rtio (P <.5, Fig. 2). For M. shriflorus, higher wter level only led to higher lef mss rtio in the m uril tretment (P <.5, Fig. 2). These results indited tht wter level rther thn uril depth ws the primry ftor in regulting iomss llotion of oth speies ADH tivity ADH tivity of oth speies ws ffeted y wter level nd/or uril depth, with signifint intertion (P <.1, Tle 1). Higher wter level led to higher ADH tivity in C. reviuspis. However, higher wter level led to higher ADH tivity in M. shriflorus without uril, ut lower tivity in the deeper uril tretments (P <.5, Fig. 3). Along with inresing uril depth, ADH tivity inresed in oth speies t the m wter level, ut deresed in M. shriflorus t the 4 m wter level (P <.5, Fig. 3). It ws ler tht the responses of ADH tivity to the two stresses were speies-speifi, depending on stress type nd intensity Solule sugr nd strh ontents Solule sugr ontent of oth speies nd strh ontent of C. reviuspis ws ffeted y oth wter level nd uril depth, nd strh ontent of M. shriflorus ws only ffeted y wter level (P <.1, Tle 1). For C. reviuspis, solule sugr ontent inresed with inresing wter level nd uril depth (P <.5, Fig. 4). Strh ontent deresed with inresing wter level or inresing uril depth t the m wter level, ut hd no hnge t the 4 m wter Solule sugr ontent (mg g -1 ) m wter level 4 m wter level d Misnthus 5 1 Strh ontent (mg g -1 ) Misnthus 5 1 Buril depth (m) 5 1 Buril depth (m) Fig. 4. Solule sugr nd strh ontents of reviuspis nd Misnthus shriflorus rmets growing on three sediment uril depths nd in two wter levels. Results re expressed s men ± S.E. (n = 4). Different letters indite signifint differene mong tretments t the.5 signifine level.

6 Y. Pn et l. / Aquti Botny 1 (212) level. For M. shriflorus, higher wter level led to lower solule sugr nd strh ontents, ut the highest solule sugr ontent ws in the 5 m uril depth + m wter level tretment (P <.5, Fig. 4). Therefore, non-struturl rohydrte of C. reviuspis ws more sensitive to oth flooding nd sedimenttion ompred to M. shriflorus. 4. Disussion Growth responses of oth speies were similr in this experiment. Either higher wter level or deeper uril (1 m) led to lower iomss umultion nd RGR, ut uril depth hd insignifint effet on plnt growth t the higher wter level. This result supports our hypothesis 1 on the flooding-intolernt speies M. shriflorus, rther thn the flooding-tolernt speies C. reviuspis. Our results re lso onsistent with some studies, whih hve found tht dominne of flooding over sedimenttion in regulting plnt growth nd distriution (Piere nd King, 27). It seems tht flooding is stronger environmentl stress on plnt growth thn does sedimenttion in oth speies when the two stresses operte simultneously. In ontrst, Lowe et l. (21) hve found tht sedimenttion during flooding n further derese the survivl nd growth of riprin plnts. Therefore, the growth responses of wetlnd mrophytes to flooding nd sedimenttion might e speies-speifi. The restrining effet on the growth of oth speies might e relted to hypoxi in roots, sine oth flooding nd sedimenttion n limit plnt growth through reduing oxygen vilility in root zones (Little nd Mun, 1996; Ferreir et l., 29). ADH tivity is usully onsidered s diret inditor of oxygen defiieny in root tissues (Chen et l., 25). A higher ADH tivity in roots of oth speies might indite tht either higher wter level or deeper uril redues oxygen vilility in root zones (Little nd Mun, 1996; Ferreir et l., 29). Compred to the singleftor response in C. reviuspis, higher ADH tivity in the 5 m uril depth + 4 m wter level tretment might indite tht oth flooding nd sedimenttion onsistently led to higher level of oxygen shortge in roots. The limtive strtegy of oth speies to flooding nd sedimenttion n e ssoited with noxi. Our study lso showed dominne of wter level over uril depth in regulting iomss llotion nd non-struturl rohydrte ontent of oth speies. These results prtly support our hypothesis 2 on M. shriflorus, rther thn C. reviuspis. Both speies hd similr responses to higher wter level, suh s higher lef mss rtio nd lower strh ontent. A higher lef mss rtio is fvorle for plnts to emerge from wter surfe to quire oxygen in the low-oxygen environments (Voesenek et l., 24). A lower strh ontent might indite onsumption of lrge mounts of rohydrte due to fermenttive metolism (Chen et l., 25), sine strh n e trnsformed into solule sugr to stisfy the energy requirement of neessrily physiologil tivity. The responses of root mss rtio nd solule sugr ontent in oth speies were different under higher wter level or deeper uril onditions. A lower root mss rtio in C. reviuspis s response to higher wter level might e n effetive strtegy to redue oxygen demnd of elow-ground tissues (Nidoo nd Mundree, 1993). Besides, higher solule sugr ontent in C. reviuspis s response to higher wter level nd deeper uril might indite tht this plnt n supply enough energy to mintin neroil respirtion under noxi onditions (Li et l., 27). In ontrst, deeper uril hd no effet on solule sugr ontent of M. shriflorus t the higher wter level. The low-elevtion speies C. reviuspis might e more sensitive to noxi thn does the highelevtion speies M. shriflorus, s lso suggested y Qin et l. (21) nd Luo et l. (28). Therefore, oth speies n limte to flooding or sedimenttion through djustments of iomss llotion nd rohydrte metolism. It ws interesting tht shllower uril stimulted the growth of C. reviuspis rther thn M. shriflorus, inditing tht not ll wetlnd mrophytes hd the stimultive responsiility. Atully, the stimulted effets y shllow uril hve een oserved in plnts in tidl wetlnd, slt mrsh or dune eosystems (Mun et l., 1996; Zho et l., 27; Sun et l., 21). In order to restore degrded wetlnds, using thin-lyer sediment uril to promote the vigor of plnts ws effetive in some speies (Ford et l., 1999). The mehnisms my e relted to the improved soil onditions for plnt growth nd temporry espe from hrmful soil pthogens, whih will stimulte root growth (Sun et l., 21). It is ler tht, mny ftors, suh s stress intensity nd iologil differenes mong speies, should e onsidered in order to restore degrded wetlnds using shllower uril to promote plnt growth. Aknowledgments The uthors gretly ppreite Prof. Jn Vermt nd two nonymous reviewers for providing onstrutive suggestions on n erlier version of this mnusript. We lso thnk Prof. Q. Zeng for improvement of lnguge nd Dr. B.H. Pn for some helps in field dt olletion. This reserh ws supported y Knowledge Innovtion Progrm of the Chinese Ademy of Siene (KZCX2-YW-435), the Ntionl Bsi Reserh Progrm of Chin (212CB4175) nd the Ntionl Nturl Siene Foundtion of Chin (317325). Referenes Bremner, J.M., Inorgni forms of nitrogen. In: Blk, C.A. (Ed.), Methods of Soil Anlysis. Amerin Soiety of Agronomy, pp Chen, H.J., Qulls, R.G., Blnk, R.R., 25. Effet of soil flooding on photosynthesis rohydrte prtitioning nd nutrient uptke in the invsive exoti Lepidium ltifolium. Aqut. Bot. 82, Chen, X.S., Xie, Y.H., Deng, Z.M., Li, F., Hou, Z.Y., 211. A hnge from phlnx to guerrill growth form is n effetive strtegy to limte to sedimenttion in wetlnd sedge speies reviuspis (Cyperee). Flor 26, Ferreir, C.S., Piedde, M.T.F., Frno, A.C., Gonç lves, J.F.C., Junk, W.J., 29. 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7 4 Y. Pn et l. / Aquti Botny 1 (212) 35 4 Voesenek, L.A.C.J., Rijnders, J.H.G.M., Peeters, A.J.M., vn de Steeg, H.M.V., de Kroon, H., 24. Plnt hormones regulte fst shoot elongtion under wter: from genes to ommunities. Eology 85, Wlls, R.L., Wrdrop, D.H., Brooks, R.P., 25. The impt of experimentl sedimenttion nd flooding on the growth nd germintion of floodplin trees. Plnt Eol. 176, Yemn, E.W., Willis, A.J., The estimtion of rohydrtes in plnt extrts y nthrone. Biohem. J. 57, Zho, W.Z., Li, Q.Y., Fng, H.Y., 27. Effets of snd uril disturne on seedling growth of Nitrri spherorp. Plnt Soil 295, Zheng, J.M., Wng, L.Y., Li, S.Y., Zhou, J.X., Sun, Q.X., 29. Reltionship etween ommunity type of wetlnd plnts nd site elevtion on sndrs of the Est Dongting Lke, Chin. Forest. Stud. Chin 11,