Growth Response of Hydroponic Rice Seedlings at Elevated Concentrations of Potassium Chloride

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1 J gri Rurl Dev 6(1&2), 43-53, June 28 ISSN ville online t JRD Journl of griulture & Rurl Development Growth Response of Hydroponi Rie Seedlings t Elevted Conentrtions of Potssium Chloride M. R. SHIUR 1,. H. M. SHMIM 2* & S. KWI 3 1&3 The United Grdute Shool of griulturl Sienes, Iwte University, Moriok-2855, Jpn 2 Shool of griulture nd Rurl Development, ngldesh Open University, Gzipur-175, ngldesh STRCT hydroponi experiment ws onduted in the greenhouse to oserve the effet of potssium hloride (KCl) on growth, mro elements nd sodium (N) onentrtion of rie seedlings (Oryz stiv L. v. Hitomeore). The plnts were grown up to 14 dys fter tretments (DT) treted with, 1, 2 nd 3 mm KCl. Shoot dry weight (dw) deresed signifintly in the 1 mm KCl tretment, indited tht rie seedlings were highly sensitive (glyophytes) to KCl. However, root dw inresed in the 1 mm KCl tretment s ompred to other tretments, indited tht KCl ould enhne root dw t lower onentrtion. The result indited tht the shoot of rie seedlings ws highly sensitive to KCl thn tht of root. Shoot height, root length nd lef numer deresed signifintly in the 2 nd 3 mm KCl tretments, while the width of lef lde deresed signifintly only in the 3 mm KCl tretment. Considering 1% dw redution the ritil toxiity levels (CTL) of K in shoot ws 6.4 mg g -1 dw nd 23.3 mg g -1 dw in root. Potssium hloride deresed lium (C), mgnesium (Mg) nd N onentrtions oth in shoot nd root, indited tht K hd ntgonisti reltionships with C, Mg nd N in rie seedlings. Phosphorus (P) onentrtion deresed in shoot in the 3 mm KCl tretment indited tht the toxi effete of KCl on P. Potssium onentrtions inresed in shoot nd root with the inresing KCl onentrtions in the nutrient solution. The sensitivity response of the elements in rie ws N>Mg>C>P under elevted onentrtions of KCl. Key words: Clium, hydroponi, mgnesium, potssium, potssium hloride, rie, sodium. INTRODUCTION Some plnts ould enounter slt stress, ut most plnts re ffeted dversely y high levels of slt. Exess slts ommonly use redution in growth nd yield of most griulturl rops. It ws onsidered tht redution is due to diret effets of ions on photosynthesis tht led to redue growth. The effet of slt on growth redution is not uniform mong ions; some re more toxi thn the others. The toxiity of n equmolr onentrtion of one ioni speies is greter thn tht of omintion of ions (ernstein, 1975). lthough the enzymes of glyophytes (slt sensitive) nd hlophytes (slt resistnt) re eqully sensitive to slts, the effets of soil solution slts on plnt metolism vry mong ioni speies nd etween glyophytes nd hlophytes. In glyophytes, N + slts re more toxi thn K + slts, while in hlophytes, toxiity follows the generl pttern: K 2 SO 4 > KCl> N 2 SO 4 = NCl (Egn nd Ungr, 1998). The mentioned slts ould e umulted in soils nd severely inhiit plnt growth. They indue plsmolysis (wter moves out of the plnt into the solution) (Tn, 1998). Intensive reserh * Corresponding uthor: ssistnt Professor (Soil Siene), SRD, OU, Gzipur-175, E-mil: ulhsnts@yhoo.om 28 Shool of griulture nd Rurl Development, ngldesh Open University, ll rights reserved.

2 M. R. Shiur et l. egn in the 195s, when the U.S. slinity l showed tht some plnts n grow fster with low slt ontent in their tissues nd the shoot slts re ontrolled y the root (Orutt nd Nilsen, 2). More thn 1 plnt fmilies ontin slt-tolernt speies (ronson, 1989). Most of the fmilies ontin less thn 1 slt tolernt speies, ut Chenopodiee ontins over 35 (Orutt nd Nilsen, 2). Slts of the soil solution govern the slinity properties of soils. On the sis of slinity tolerne plnts n e lssified into two rod groups (1) Glyophytes: these plnts re sensitive to reltive low soil slt onentrtion. Most of the griulturl rops nd higher plnts re glyophytes. mong rops, mize, onion, itrus, pen, lettue nd en re highly sensitive to slt (Tiz nd Zeiger, 22). Glyophytes n e lssified s () Euglyophytes or true glyophytes or strit glyophytes or sensitive glyophytes or intolernt glyophytes: plnt whose growth nd fitness dereses when expose to ny level of slinity (less thn pproximtely 1 mm) () Oligte or Norml glyophytes: these plnts n tolerte very low slinity ut n t tolerte soil slinity greter thn pproximtely 1 mm (2) Hlophytes: plnts those re le to grow in the presene of high slt ondition. These plnts often require some slt to grow their est. It is onsidered tht more thn one-third of extnt plnt fmilies hve hlophyti memers nd out 25 speies of hlophytes re found in the world s slt mrshes nd desert flts (Glenn, 1997). Hlophytes n e lssified s () Euhlophytes or true hlophytes or strit hlophytes: hlophytes ould grow in onditions of extreme high slinity (more thn 5 mm) efore redution in growth or fitness () Oligte hlophytes: plnts tht require slt in the growth medium to reh their mximum growth potentil nd hve their highest fitness. This type of plnt does not ttin their highest fitness t low soil slinity (less then 1 mm). Modertely high soil slinity (5 mm) is required to ttin mximum fitness () Fulttive hlophytes: these plnts ttin hlophyti nture only fter experiene moderte slinity in the soils or s n erosol. Until now, mny reserhes hve een done to lssify the plnts relted to slt tolerne tivity. Most of whih were onduted with N nd its derivtives together with other slt, ut the dt of KCl reserh in hydroponi ulture were not dequte. Therefore, the present experiment ws onduted to define the lssifition of Hitomeore rie vriety together with its mroelements nd N under elevted onentrtions of KCl. MTERILS ND METHODS Seedling preprtion nd plnt ulture Rie seeds were (Oryz stiv L. v. Hitomeore) surfe sterilized with 2% (w/v) hlorinted lime [C(OCl) 2 ] for 45 minutes, rinsed with tp wter ontinuously for 1 hour nd soked etween moistened towels overed with wrpping pper t 25 C for 72 hours in n eletri inutor. Germinted seeds were pled on plsti net in the seed ox ontining 2 mm CCl 2 solution in the greenhouse of Iwte University, Moriok, Jpn. fter 7 dys, the hlorinted solution in the seed ox ws repled with ½-strength modified Hoglnd-rnon nutrient solution for rie (Hewitt nd Smith, 1975). This ws done 2 times efore strting the tretments. totl of 24 dys were required for the seedling preprtion. ll plnts were llowed to grow until 5 th full lef nd some plnts lso ontined 6 th lef t emergene stge. fter 24 dys, seedlings were trnsplnted in unhes (5 plnts were wrpped with sponge ruer to mke 1 unh) nd 8 unhes were pled in one pot (pity 5 liters) filled with full strength rie solution ontining 1 µm Fe 3+ -itrte. The plnts were treted with KCl up to 14 dys fter tretments (DT). The tretments of KCl were, 1, 2 nd 3 mm. The plnts were grown in the greenhouse nd the ph of the solutions ws 5.5 t the time of solution preprtion. The nutrient solutions were renewed every week during the study (July 22, 25 to ugust 28, 25). Compositions of full-strength nutrient solution The ompositions of the full-strength nutrient solutions were 1 mm NH 4 NO 3, 1 mm K 2 SO 4,.8 mm MgSO 4,.5 mm CCl 2,.5 mm NH 2 PO 4, 1 µm MnSO 4, 1 µm CuSO 4, 1 µm ZnSO 4, 3 µm H 3 O 3,.5 µm H 2 MoO 4 nd 1 µm Fe 3+ -itrte. Smple olletion nd preprtion fter 14 DT, 3 unhes were tken from eh tretment for determining some growth prmeters nd P, K, C, Mg nd N. The plnts were wshed with deionized wter properly nd seprted into shoot 44

3 Growth response of hydroponi rie seedlings t elevted onentrtions of KCl nd root with sterilized sissor nd were dried for 48 hours t 55-6 C in n eletri oven (ISUZU, Isuzu Seiskusho Compny, Tokyo, Jpn). The smples were ut into smll piees nd digested with nitriperhlori id mixture (Piper, 1942) nd nlyzed. Shoot height, root length nd width of lef lde Shoot height ws mesured from the ulm se to the tip of the longest lef nd root length ws mesured from the root-shoot juntion to the tip of the longest root (edin nd Mehrg, 22). The width of lef lde ws mesured in the middle position of fully developed sixth lef with sle. Chlorophyll index (SPD vlue) The hlorophyll index of fully developed leves (sixth) on 14 DT ws mesured using SPD- 52 hlorophyll meter (Minolt Cmer Compny, Tokyo, Jpn). In eh lef the hlorophyll index of 5 points were mesured nd the verge ws lulted. Mens of eh unh were otined. verge of the dt of 3 unhes ws lulted. Chemil nlysis Phosphorus ws determined olorimetrilly using UV-visile Spetrophotometer (model UV mini 124, Shimdzu Corp., Kyoto, Jpn) t 42 nm wvelengths fter developing the yellow olor with vndomolydte s desried y rton (1948) nd Jkson (1958). Potssium, C, Mg nd N were determined with the Hithi 17-3 tomi sorption spetrosopy (S) (Hithi, Tokyo, Jpn). Experimentl design The experiment ws ompletely rndomized lok design with 3 replitions. Dt were nlyzed y nlysis of vrine (SS, 199). Clultion proedure Reltive shoot weight in % (RSW) = (shoot weight of speifi tretment/shoot weight of ontrol tretment) 1. Reltive root weight in % (RRW) = (root weight of speifi tretment/root weight of ontrol tretment) 1. Conentrtion of elements in plnt tissue refers to the element present in one g of smple [mg or µg of the element g -1 dry weight (dw)] while umultion refers to the speifi element present per plnt shoot or root (mg or µg of the element plnt -1 shoot or root). Uptke is eing onsidered s the totl umultion (umultion in shoot plus umultion in root). Trnslotion (%) ould e expressed in nutrient umultion in shoot 1/ totl umultion (shoot + root). Regents ll hemils used were of nlytil regent grde. ll solutions were prepred previously with MQ wter [(18.2 MΩ m -1 ), purified y Milli-RO 6, Millipore orportion, US]. Stok solution of 3 M KCl ws prepred y dissolving KCl slt (Knto Chemil Compny, Tokyo, Jpn) in MQ wter. This stok solution ws kept t room temperture in n id wshed regent ottle in the lortory in norml ondition. Working solutions of, 1, 2 nd 3 mm KCl were prepred every week y diluting the stok solution with deionized wter. Glsswre used for this experiment ws soked in.1 N nitri id solutions nd were rinsed with MQ wter. RESULTS ND DISCUSSION Visile symptoms Severe neroti symptom (urning of young lef tips nd deth ssoited with disolortion nd dehydrtion of old leves) ws visulized in the leves of 3 mm KCl tretment. In the 3 mm KCl tretment, the older leves died ompletely. Yellowing of younger lef inresed with the severity of KCl onentrtions. Greening of the leves deresed with inresing KCl onentrtions in the nutrient solution, this ws most proly due to the redution of hlorophyll ontent in the leves. The youngest leves filed to unfold, lef size (length nd width) deresed drstilly nd visile growth redutions were found in the 3 mm KCl tretment. Curling of the younger leves followed y shriving ourred. The most ommon symptom, however, ws growth redution. Potssium hloride toxiity resulted in poor root length, reddish disolortion nd felt slippery to touh my e 45

4 M. R. Shiur et l. due to deteriortion of the middle lmell y exess K. Potssium ould interfere physiologil vilility of C (Mrshner, 1998) whih my led root funtion disruption. In this experiment, root length inresed in the 1 mm KCl tretment, indited tht low onentrtion of KCl enhned root elongtion whih ws most proly due to the positive effet of hlorine (rdy nd Weil, 22). The result of the present study indited tht t high level of vilility of KCl resulted in hrmful physiologil response in the rie seedlings tissues (toxiity rnge). Chlorophyll index (SPD vlue) In the present experiment, the hlorophyll index deresed with the inresing KCl onentrtions in the nutrient solution (dt not shown), indited tht exess KCl redued the prodution of hlorophyll ontent in the leves. Dry mtter yield Potssium hloride deresed shoots dw in the 1, 2 nd 3 mm KCl tretments. However, root dw inresed in the 1 mm KCl tretment, ut deresed in the 2 nd 3 mm KCl tretments (Fig. 1). The highest shoot dw ws reorded in the ontrol nd the lowest ws in the 3 mm KCl tretments, respetively. Potssium hloride in the nutrient solution ws ountle for 1, 19 nd 27% shoot dry mtter yield redution in the 1, 2 nd 3 mm KCl tretments, respetively. However, 1% dw inresed in root in the 1 mm KCl tretment [this ws most proly due to the positive effet of Cl on root length (rdy nd Weil, 22)] while 19 nd 24% dw deresed in the 2 nd 3 mm KCl tretments, respetively. Our experimentl dt indited tht the rie seedlings were KCl sensitive (oligte glyophytes) nd shoot ws more sensitive thn tht of root. 1~2 mm KCl ould e the limiting ftor for shoot of rie seedlings in the hydroponi ulture. Growth redution ws most proly due to the toxi effets of KCl on enzymti tivity. It is reported tht the enzymes of glyophytes nd hlophytes (Greenwy nd Osmond, 1972; Greenwy nd Munns, 198) re inhiited y slt in vitro eqully. We lulted 1, 94, 81 nd 73% RSW nd 1, 11, 81 nd 76% of RRW for, 1, 2 nd 3 mm KCl tretments, respetively, indited tht with n inrese of KCl levels redued the reltive growth. Shoot height nd root length Shoot height deresed with inresing KCl in the nutrient solution nd the lowest vlue ws reorded in the 3 mm KCl tretment. In 1 mm KCl tretment, root length inresed signifintly s ompred to other tretments (Fig. 1). This inrese ws most proly due to the positive effet of Cl on root length (rdy nd Weil, 22). However, the root length deresed signifintly in 2 nd 3 mm KCl tretments. In the higher KCl tretments, C onentrtions deresed in root (Fig. 2). The redution of C onentrtions might e involved to redue the root length, euse C is minly relted to root elongtion. Under norml onditions, the ytosol of higher-plnt ells ontins 1-2 mm K + nd 1 to 1 mm N + n ioni environment in whih mny enzymes funtion optimlly (Mrshner, 1998). In presene of high KCl (3 mm), n normlly high rtio of K + nd high onentrtions of totl slts my intivte enzymes nd inhiits protein synthesis. t higher onentrtions of K +, K + my disple C 2+ from the plsm memrne of rie root hirs, resulted in hnge in plsm memrne permeility. Crmer et l. (1985) found C ws repled y N in otton roots nd deresed the norml funtion of root. Lef numer Lef numer deresed signifintly in 2 nd 3 mm KCl tretments. The highest lef numer ws reorded in the ontrol tretment nd the lowest ws in the 3 KCl tretments (Fig. 1). This ws most proly due to the redued plnt growth hormone prodution or n inrese in the prodution of sisi id () (Nilsen nd Orutt, 1996). This supposition needs to e verified in the future. This redution of lef numer might e responsile for the redution of shoot dw (Fig. 1). Width of lef lde The width of lef lde deresed signifintly in the 3 mm KCl tretment. The highest width of lef lde ws reorded in ontrol tretment nd the lowest ws reorded in 3 mm KCl 46

5 Growth response of hydroponi rie seedlings t elevted onentrtions of KCl tretments, respetively (Fig. 1). This ws most proly due to the ft tht KCl redued the tivity of plnt growth regultors. It ws found tht protein synthesis is redued in soyen leves growing in NCl sline ondition whih might e due to hloride toxiity in sensitive speies (Mrshner, 1998). Therefore, the other possile use my e redution of protein synthesis in the higher KCl onentrtion. () g/5 plnts C Shoot D Root d g/5 plnts () Height (m) Shoot C Root d Length (m) () Lef numer Lef numer C Width of lef lde Width of lef lde (m) KCl onentrtion (mm) in nutrient solution Fig 1. () Dry mtter yield, () shoot height nd root length; nd () lef numer nd width of lef lde of rie seedlings with different levels of KCl. rs with different letters re signifintly different (p<.5) ording to Ryn-Einot-Griel-Welsh multiple rnge test. 47

6 M. R. Shiur et l. Tiller numer No new tiller ws found even in the ontrol tretment during the experiment (38 dy fter germintion) or 14 DT. Therefore, it ws not wise to drw ny omment relted to effet of KCl on tiller formtion. It ould only e sid tht the time durtion ws not suffiient for the formtion of new tiller in this experiment. Effet of KCl on phosphorus The onentrtions of P did not hnge in shoot in 1 nd 2 mm of KCl tretments s ompred to ontrol tretment, ut deresed signifintly in the 3 mm KCl tretment (Fig. 2). This redution ws most proly due to severe toxiity of KCl on plnt growth. Chlorine is one of the non-metl mironutrients nd euse of its non-metlli hrter, it is similr to P. Due to this hemil similrity ompetitive proess in their uptke ould e expeted. In the se of root, the onentrtion deresed signifintly in the 1 mm KCl tretment, whih ws most proly due to dilution effet, euse in this tretment root dw nd length inresed signifintly. For other tretments no hnge of P onentrtions were found. Phosphorus onentrtions deresed 12% in shoot nd 9% in root in 3 mm KCl tretment in the nutrient solution. The umultion lso deresed signifintly in shoot nd root in the 3 mm KCl tretment whih indited the toxi effet (Tle 1). Phosphorus nd K rtio in shoot nd root deresed signifintly with the KCl tretments indited the negtive effet of KCl on P onentrtion (Tle 2). Typil P onentrtions in ommon plnts re 2-4 mg g -1 dw (Lio et l., 24) or 3-4 mg g -1 dw (Mengel nd Kirky, 21) during the vegettive growth stge, indited tht the P onentrtions of the experimentl plnts ws higher (Fig. 2), this ws most proly due to speies of rie seedlings. Phosphorus trnslotion ws not muh ffeted in this experiment y the used KCl in the nutrient solution (Tle 1). Tle 1. umultion (mg plnt -1 shoot or root) in shoot nd root nd trnslotion (%) from root to shoot of nutrient elements of rie seedlings grown in nutrient solution t different levels of KCl umultions (mg plnt -1 shoot or root) Tretments P K C Mg N (mm KCl) Shoot Root Shoot Root Shoot Root Shoot Root Shoot Root C.65d C C C D.8.21C.14.14C.6 mm KCl Trnslotion (%) Mens followed y the different letters in eh olumn re signifintly different (p=.5) Effet of KCl on potssium Potssium onentrtions inresed signifintly oth in shoot nd root with the inresing KCl onentrtions in the nutrient solution (Fig. 2). In shoot, the highest onentrtion ws reorded in the 3 mm KCl tretment. Not only onentrtion ut lso umultion inresed in shoot with tretments (Tle 1). In the highest onentrtion of KCl in the nutrient solution, the trnslotion of K from root to shoot did not inrese mrkedly (Tle 1). The inrese of K onentrtion nd umultion in shoot nd in root might e due to luxury onsumption of K (Mrshner, 1998) whih is norml phenomenon in high level of K supply. The K ontent inresed in vrious orgns [exept grins nd seeds whih mintin reltively onstnt K ontent of.3% of the dw] y inresing the K supply to plnt root (Mrshner, 1998). The vlue of K onentrtion is 1-4% (1-4 mg K g -1 dw) of dw in helthy lef tissue of most plnts (rdy nd Weil, 22). However, it ws lso pointed out tht K requirement for optiml plnt growth is in the rnge of 2-5% (2-5 mg g -1 48

7 Growth response of hydroponi rie seedlings t elevted onentrtions of KCl dw) of plnt vegettive prts, fleshy fruits nd tuers (Mrshner, 1998). In the highest onentrtion of KCl, the plnts sor high onentrtions of K, resulted in the toxiity symptoms. t high level of vilility of n element, the plnt will tke up lrge mount of the nutrient elements for its own good (toxiity rnge), result hrmful physiologil retions in the plnt ell. In this experiment, the K onentrtion in shoot of ontrol seedlings ws 35.9 mg g -1 dw, indited the norml onentrtion of K in shoot tissues. It ws lso reported tht K onentrtion in shoot of hydroponi rie ws 44.1 mg g -1 dw (Shiur et l., 26) nd 6.2 mg g -1 dw in hydroponi rley (lm et l., 21) of ontrol plnts. Effet of KCl on lium Clium onentrtions deresed oth in shoots nd roots with the inresing KCl onentrtions in the nutrient solution. The signifint redutions were otined in 2 nd 3 mm KCl tretments (Fig. 2). It is well known tht KCl in solution is dissoited s K + nd Cl - ions. s K + nd C 2+ oth re tions, therefore, ntgonisti reltionships etween them ould e possile. Our result showed tht the ntgonisti reltionship etween K + nd C 2+ ; nd the C onentrtions deresed y 22% in shoot nd 27% in root in the 3 mm KCl tretment. When the K supply is undnt in the rooting medium luxury onsumption of K often ours whih deserve ttention for its possile interferene with the uptke nd physiologil vilility of C nd Mg (Mrshner, 1998). Clium stilizes ell memrnes y ridging phosphte nd roxylte groups of phospholipids (Cldwell nd Hug, 1981) nd preferentilly protein t memrne surfes (Legge et l., 1982). There n e n exhnge etween C t these inding sites nd other tions (eg. K +, N + or H + ) resulted in C onentrtions deresed. Clium umultions were lso deresed signifintly y the KCl tretments ut the trnslotion ws not ffeted muh (Tle 1). Clium onentrtion in plnt tissues vries etween.1->5% (1-5 mg C g -1 dw) of dw depending on the growing onditions, plnt speies nd plnt orgn (Mrshner, 1998). The experimentl plnts ontined 3.44, 3.12, 2.64 nd 2.68 mg C g -1 dw in shoot tissues in, 1, 2 nd 3 mm KCl tretments, respetively, indited tht the norml levels of C onentrtions. The highest C/K rtio ws otined (oth in shoot nd root) in ontrol tretment nd the lowest ws in 3 mm KCl tretment, indited tht the lowest C onentrtion ws in the highest KCl onentrtion in the nutrient solution. The hydrted K + hs rdius of.331 nm, ut C 2+ hs the ioni rdius of.99 nm (Mrshner, 1998). Therefore, K strongly sustitutes or ompetes with C 2+ in vrious retions involving either of these ions. Effet of KCl on mgnesium Mrginl onomitnt reltionship ws found etween K nd Mg in shoot in the 1 mm KCl tretment (Fig. 2d). It my e due to the onentrtion effet euse shoot dw deresed signifintly in this tretment (Fig. 1). Mgnesium onentrtions deresed signifintly in shoot in 2 nd 3 mm tretments nd in root in 1, 2 nd 3 mm KCl tretments. This is logil euse K + nd Mg 2+ oth re tions, therefore, ntgonisti reltionship etween them might e ourred. Some reports indited tht the Mg uptke n strongly e depressed y K + nd NH + 4 (Kurvits nd Kirky, 198), C 2+ nd Mn 2+ (Heenn nd Cmpell, 1981) s well s y H +. Mgnesium onentrtion deresed y 3% in shoot nd 33% in root in 3 mm KCl tretment in the nutrient solution. The dt presented in Tle 1 showed tht the umultion of Mg ws lso depressed y the used KCl tretments, indited tht the ntgonisti reltionship etween K nd Mg, however, the trnslotion of Mg ws not ffeted y KCl (Tle 1). The Mg nd K rtio in shoot nd in root deresed signifintly with the KCl tretments (Tle 2). In presene of exess ville K, K my e tken up s high level (Mrshner, 1998) whih interfering the uptke nd physiologil vilility of Mg, resulted in the derese in the Mg/K rtio in the present experiment. In lef tissues, the threshold vlue for the ourrene of Mg-defiieny symptoms is in the region of out 2 mg g -1 dw (Mengel nd Kirky, 21). The test plnts ontined 3.18, 3.4, 2.54 nd 2.22 mg Mg g -1 dw in, 1, 2 nd 3 mm KCl tretments, respetively, indited tht the vlue in shoot tissues ws over the ritil defiieny level of Mg. It ws lso reported tht the Mg requirement for optimum plnt growth is in the rnge of % ( mg Mg g -1 dw) of the vegettive prts (Mrshner, 1998), indited tht the shoot of the experimentl plnts ontined more or less norml onentrtions of Mg. Potssium hs hydrted rdius of.331 nm nd Mg 2+ 49

8 M. R. Shiur et l. hs the rdius of.65 nm (Mrshner, 1998). s result, Mg ould e repled strongly y K in vrious retions in this present experiment. () P (mg g -1 dw) 1 5 Shoot Root 8 4 P (mg g -1 dw) () K (mg g -1 dw) 1 5 D C K (mg g -1 dw) () C (mg g -1 dw) C (mg g -1 dw) (d) Mg (mg g -1 dw) Mg (mg g -1 dw) KCl onentrtion (mm) in nutrient solution Fig 2. Effet of KCl on the onentrtion of () P, () K, () C nd (d) Mg in shoot nd root of rie seedlings. rs with different letters re signifintly different (p<.5) ording to Ryn-Einot-Griel-Welsh multiple rnge test. 5

9 Growth response of hydroponi rie seedlings t elevted onentrtions of KCl Tle 2. Conentrtion rtio of elements in shoot nd in root of rie seedlings grown in nutrient solution t different levels of KCl Tretments P/K C/K Mg/K N/K (mm KCl) Shoot Root Shoot Root Shoot Root Shoot Root C C C C D D D.18 d.15 C.78 Mens followed y the different letters in eh olumn re signifintly different (p =.5) Effet of KCl on sodium Sodium onentrtions deresed signifintly in shoot nd root with the inresing KCl onentrtions in the nutrient solution (Fig. 3), indited tht the severe ntgonisti reltionship etween these two elements. Higher plnts hve developed high seletivity in the uptke of K s ompred with tht of N nd this is prtiulrly ovious in trnsport to shoot (Mrshner, 1998). For this reson luxurious onsumption of K ws tken ple in the high KCl onentrtions in the nutrient solution. Potssium hs more or less similr hydrous rdius (.331 nm) like N + (.358 nm) (Mrshner, 1998). In nother wy, it hs lso een pointed out tht N hs the ioni rdii of 1.65~2.5. Å while in K the ioni rdii is 2.35~2.66Å (iggin et l., 21). Therefore, strong ompetition etween them ould e possile, resulted in lower onentrtions of N in shoot nd root in this experiment (Fig. 3). Moreover, oth re positively hrged tions. In some ntrophili plnts, K n e repled when N ontent is high (Mrshner, 1998). Similrly, opposite result ould e expeted in higher KCl solution in this present experiment. In sugr eet N is redily trnsloted to the shoot where it reples most of the K (Mrshner, 1998). In this experiment, not only onentrtions ut lso umultions nd trnslotions of N deresed with the inresing KCl onentrtions in the nutrient solution (Tle 1). Sodium onentrtion deresed y 41% in shoot nd 56% in root in the 3 mm KCl tretment. Potssium onentrtions inresed y 75%, 114% nd 159% in shoot ut the vlues were 13, 72 nd 56% in root in 1, 2 nd 3 mm KCl tretments, respetively. The highest N nd K rtio in shoot nd in root were otined in the ontrol tretment (Tle 2). The rtio deresed grdully nd signifintly nd the lowest vlue ws in the 3 mm KCl tretment. This result indited tht the highly ntgonisti reltionships etween K nd N. When slinity is used y N slt, it my derese K ontent in plnt tissue y ompetition, s oth of them hve similr ioni rdii t hydrted ondition. N (mg g -1 dw) C Shoot Root C N (mg g -1 dw) KCl onentrtion (mm) in nutrient solution Fig 3. Effet of KCl on the onentrtion of N in shoot nd root of rie seedlings. rs with different letters re signifintly different (p<.5) ording to Ryn-Einot- Griel-Welsh multiple rnge test. 51

10 M. R. Shiur et l. Critil toxiity levels (CTL) of K in shoots nd roots Considering 1% dw redution the CTL of K ws lulted s 6.4 mg g -1 dw in shoot nd 23.3 mg g -1 dw in root, though the CTL were suggested to e very muh dependent on the speies nd physil onditions of plnts, vrieties, environmentl onditions espeilly temperture, nutrient ompositions nd methodology of the experiments. The CTL were lulted from the polynomil two order growth urves (Fig. 4) where the equtions were y = -.71x x nd y = x x for shoot nd root, respetively. For shoot, the highest growth ws in ontrol tretment nd the vlue ws mg/5 plnts nd the 1% dw redution ws lulted from this vlue. In se of root, the vlue of ontrol tretment ws 25.4 mg/5 plnts nd the vlue ws used for the determintion of CTL in root. y using the similr equtions the CTL of rseni (s) were reported y the present uthor in rie, sorghum nd rley (Shiur et l., 28). () mg 5 plnts Fig 4. Shoot CONCLUSION y = -.71x x R 2 = Two order polynomil growth urve () shoot nd () root of rie seedlings with different KCl onentrtions in plnt tissues The dry weight deresed signifintly in shoot in the 1 mm KCl tretment, ut in root the signifintly redutions were otined in 2 nd 3 mm KCl tretments. Shoot height, root length nd lef numer deresed signifintly in 2 nd 3 mm KCl tretments, ut width of lef lde deresed in the 3 mm KCl tretment. Therefore, rie plnts ould usully e lssified s oligte glyophytes where shoots were more sensitive to KCl thn tht of roots. The ritil toxiity levels (CTL) of K were 6.4 mg g -1 dw in shoot nd 23.3 mg g -1 dw in root. From this experiment it ould e onluded tht K + shows the ntgonisti reltionships with C, Mg nd N in rie seedlings. The derese of P onentrtion ws most proly due to the toxi effet of 3 mm KCl tretment on rie seedlings. Phosphorus, C, Mg nd N onentrtions deresed in shoot y 12, 22, 3 nd 41% in the 3 mm KCl tretment, ut for root the vlues were 9, 27, 33 nd 56%, respetively. Considering the redution vlue of onentrtions, the sensitivity of these elements n e rrnged s N>Mg>C>P oth for shoot nd root in rie seedlings when KCl is present t 3 mm level. From our result it ws suggested tht smll mount of KCl (1 mm) ould e the good fertilizer for the rooting rops s the root growth inresed signifintly in the 1 mm KCl tretment, though this suggestion needs to e verified. In most ses it ws found tht KCl deresed the onentrtions of P, C nd Mg. The onentrtions of mroelements were within the norml onentrtions of plnt nutrition ut the plnt growth deresed. Therefore, it ould e suggested tht the redution of growth ws ssoited with the redution of mroelements onentrtions together with the prodution of toxi iohemil sustnes whih needs to e investigted. () mg 5 plnts Root y = x x R 2 = mg K g -1 dw LITERTURE CITED edin, M. J, nd Mehrg, Reltive toxiity of rsenite nd rsente on germintion nd erly seedling growth of rie (Oryz stiv L.). Plnt nd Soil 243, lm, S., Kmei S. nd Kwi S. 21. meliortion of mngnese toxiity in rley with iron. J Plnt Nutri 24(9), ronson, J Hloph. Dt se of Slt Tolernt Plnts of the World. Offie of rid Lnds Studies, University of rizon, Tempe, Z. 52

11 Growth response of hydroponi rie seedlings t elevted onentrtions of KCl rton, C. J Photometri nlysis of phosphte rok. nlyt Chem 2, ernstein, L Effets of slinity nd sodiity on plnt growth. nn Rev Phytopth 13, iggin, P. C, Smith, G. R., Shrivstv, I., Choe, S., Snsom M. S. P. 21. Potssium nd sodium ions in potssium hnnel studied y moleulr dynmis. iohimi et iophys. t 151, 1-9. rdy, N. C. nd Weil, R. R. 22. The Nture nd the Properties of Soils (Thirteen Edn.). N. C. rdy nd R. R. Weil, Prentie Hll, New Jersey. Cldwell, C. R. nd Hug, Temperture dependene of the rley root plsm memrneound C 2+ nd Mg 2+ -dependnt TPse. Physiol Plntrum 53, Crmer, G. R., Läuhli,. nd Polito V. S Displement of C 2+ y N + from the plsmlemm of root ells. primry response to slt stress? Plnt Physiol 79, Egn, T. P., nd Ungr, I Effet of different slts of sodium nd potssium on the growth of triplex prostrt (Chenopodiee). J Plnt Nutri 21(1), Greenwy, H. nd Munns, R Mehnisms of slt tolerne in nonhlophytes. nn Rev Plnt Physiol 31, Greenwy, H. nd Osmond C Slt responses of enzymes from speies differing in slt tolerne. Plnt Physiol 49, Glenn, E. P Mehnisms of slt tolerne in higher plnts. In Mehnisms of Environmentl Stress Resistne in Plnts. (. S. sr nd R. K. sr, Eds.), Hrwood demi Pulishers, msterdm pp Heenn, D. P. nd Cmpell L. C Influene of potssium nd mngnese on growth nd uptke of mgnesium y soyens (Glyine mx L. Merr. v. rgg). Plnt nd Soil 61, Hewitt, E. J. nd Smith T Experimentl methods for the investigtion of plnt nutrient requirements. In Plnt Minerl Nutrition (E. J. Hewitt nd T.. Smith., Eds.). The English Universities Press Ltd., London. pp Jkson, M. L Totl elementl phosphorus. In Soil Chemil nlysis Prentie-Hll, In. Englewood Cliffs, New Jersey. pp Kurvits,. nd Kirky, E The uptke of nutrients y sunflower plnts (Helinthus nnuus) growing in ontinuous flowing ulture system, supplied with nitrte or mmonium s nitrogen soure. Z Pflnzenernähr odenk 143, Lio, X. Y., Chen, T.., Lei, M., Hung, Z. C., Xio, X. Y. nd n, Z. Z. 24. Root distriutions nd elementl umultions of Chinese rke (Pteris vittt L.) from s-ontminted soils. Plnt nd Soil 261, Legge, R. L., Thompson, E., ker J. E. nd Lieermn, M The effet of lium on the fluidity nd phse properties of mirosoml memrnes isolted from postlimteri Golden Deliious pples. Plnt Cell Physiol 23, Mrshner, H Minerl Nutrition of Higher Plnts (Seond Edn.). demi Press, London. Mengel, K. nd Kirky E Iron. In Priniples of Plnt Nutrition (Fifth Edn.). (K. Mengel nd E.. Kirky, Eds.), Kluwer demi Pulishers, Dordreht. Nilsen, E. T. nd Orutt, D. M The Physiology of Plnts Under Stress: ioti Ftors John Wiley & Sons, New York. Orutt, D. M. nd Nilsen E. T. 2. Physiology of Plnts under Stress: Soil nd ioti Ftors. D. M. Orutt nd E. T. Nilsen Eds. John Wiley & Sons, In., New York. Piper, C. S Soil nd Plnt nlysis. Hssell Press, delide. SS SS/STT User s Guide (Version 6, Forth Edn.). Vol. 2. Sttistil nlysis System (SS) Institute, SS Cmpus Drive, Cry, NC. Shiur, M. R., Kitjim, N., Sugwr, R., Kondo, T., lm, S., Immul Huq, S. M. nd Kwi, S. 28. Critil toxiity level of rseni nd elementl omposition of rseni-indued hlorosis in hydroponi sorghum. Wter ir Soil Pollut DOI 1.17/s Shiur, M. R, Kitjim, N., Sugwr, R., Kondo, T., Immul Huq, S. M. nd Kwi, S. 26. Physiologil nd minerlogil properties of rseni-indued hlorosis in rie seedlings grown hydroponilly. Soil Si Plnt Nutri 52(6), Tiz, L. nd Zeiger, E. 22. Plnt Physiology (Third Edn.) (L. Tiz nd E. Zeiger, Eds.). Sinuer ssoites, In., Sunderlnd, Msshusetts. Tn, K. H Priniples of Soil Chemistry (Third Edn.) (K. H. Tn, Ed.). Mrel Dekker, In., New York. 53