Differential responses of root system and gas exchange in contrasting tomato genotypes under phosphorus starvation

Transcription

1 AJCS ():- () ISSN:3-77 Differentil responses of root system nd gs exhnge in ontrsting tomto genotypes under phosphorus strvtion Dougls José Mrques*, Ernni Clrete d Silv, Mozrt Mrtins Ferreir 3, Crlos Muríio Pglis 3, Thigo Corrê de Souz, Wilson Roerto Mluf 3, Griel Msrenhs Miel, Ewerton Dilelis Ferreir 3, Alln Klynger d Silv Loto Setor de Oleriultur e Experimentção, Universidde José do Rosário Vellno (UNIFENAS), Alfens, rzil Universidde Federl São João Del-Rei, Sete Lgos, rzil 3 Universidde Federl de Lvrs, Lvrs, rzil Instituto de Ciênis d Nturez, Universidde Federl de Alfens, Alfens, rzil Instituto de Ciênis Agráris, Universidde Federl de Uerlândi, Monte Crmelo, rsil Núleo de Pesquis Vegetl ási e Aplid, Universidde Federl Rurl d Amzôni, Prgomins, rzil *Corresponding uthor: douglsjmrques@yhoo.om.r Astrt Phosphorus (P) is n essentil mronutrient for the development of plnts. Although it is not lwys required in lrger mounts, its presene is often limited, sine the rzilin nd other soils of the world re generlly poor in this element. The ojetive of the reserh ws to evlute the development of the root system, gs exhnge nd effiieny in the sorption of phosphorus in ontrsting tomto genotypes. The experimentl design ws rndomized lok in the ftoril sheme with three tomto genotypes (Gloonnie, -9 nd F ) nd four phosphorus levels (., 3, nd mg L - ) with four replitions. Assessing the root morphology, it ws oserved tht the Gloonnie genotype hs higher root length vlue in. mg L - of P; however, with the inresing of P levels it ws greter in F genotype. This study onluded tht Gloonnie nd F presented etter performnes under phosphorus strvtion, due to etter root hrteristis nd gs exhnge tht promote higher P effiieny. esides, they my further uptke nd improve the use of the phosphorus. Here, we reveled possile redution of phosphorus nd onsequently prodution osts in tomto frming. Keywords: Solnum lyopersion, phosphorus, photosynthesis, root system. Arevitions: ATP_denosine triphosphte, CO _ron dioxide, E_trnspirtion rte, EAP_effiient sorption of phosphorus, gs_stomtl ondutne, NADPH_niotinmide denine dinuleotide phosphte, P_phophorus, Pi_inorgni phosphorus, Pn_photosynthesis, P O _Phosphorus pentoxide, RUISCO_riulose isphosphte roxylse oxygense, RuP_ Riulose-,- isphosphte. Introdution The tomto is produed in lmost ll geogrphil regions of rzil nd in different periods under different ropping systems nd different levels of ulturl mngement. This is the seond vegetle most widely ultivted in the world, whih only surpssed y the potto. The lrgest produer is Chin with. million tons t,7 million m nd produtivity of. tons per, m. rzil produed 3.9 million tons. A segment of the tomto ontriuted 3. perent of prodution (.3 million tons) nd the remining 3. perent ws lloted for industril proessing (.3 million tons) (FAOSTAT, ; IGE, ). Mximum produtivity of the tomto hs een ssoited with levels of fertilizer exeeding 3 kg of P O per, m (ros, 993), rehing up to kg of P O per, m (Filgueir, ). The inresed effiieny in the sorption of phosphorus y the tomto ould provide n ppreile redution in the levels of phosphte fertilizers, s well s, llow hrnessing the most immedite fixed phosphorus in the soil. Consequently, it would ring fvorle refletions towrds griulturl sustinility in the net inome of the rurl produer, in the hrnessing of mrginl res in terms of soil fertility, nd in the ost of fertilizer t the ntionl level. A redution of only kg of P O per, m in the utiliztion of nutrients y tomto plnts would represent svings of pproximtely.3 dollrs per, m, totling more thn.9 million dollrs on the ntionl level of tomto prodution (Silv nd Mluf, ). Among the mny nutrients neessry for the development nd prodution of plnts, phosphorus (P) oupies prominent ple due to the lrger mount required y plnts (Stuffer nd Sulewski, ) nd its defiieny is pprent in most soils (Lopes et l., ). There is signifint geneti vrition inter- nd intrspeifi in the ility of plnts to tolerte stress linked to phosphorus defiieny, lled phosphorus use effiieny (Lynh, 99; Shröder et l., ). This effiieny n e sed on superior ility to quire P from soil through hnges in morphology or rhiteture of roots, in exudtion of moilizing P omponents, or y the modifitions of inorgni phosphorus (Pi) trnsporters in plsmti memrne (Kohinet l., ). Additionlly, it n lso involve smller P mounts required in ellulr level, or more effiient remoiliztion of P within plnt (Yn et l., ).

2 Introdutions of tomto plnts with greter effiieny in the sorption of phosphorus hve een identified. Study onduted y Hohmuth et l. (9) evluted more thn tomto types (Solnum lyopersion), with t lest two of these introdutions eing highly effiient in extrting P from the poor-p solution. In one of these introdutions (PI ws desried s Gloonnie ultivr), the effiieny in the extrtion of phosphorus ws ssoited with morphologil hrteristi in the roots, when this type ws ultivted in nutrient solution ontining low ontent of P. This hrteristi, lled "ottony root", showed up in simple heritge ( reessive gene, termed rt), nd is ssoited with lrge numer of roots tht n e oserved in mirosope fter eing stined with rmine eti, when plnts re grown in solutions with low ontent ( ppm) P, while tht this response is not oserved when higher onentrtions of P ( ppm) re used (Hohmuth et l., 9). The vilility of tomto germoplsm with effiieny in the extrtion of phosphorus is ssoited with morphologil hrteristi (lrge numer of root hirs when ultivted under low levels of P), nd the simple heritility to this trit (ontrolled y reessive gene), mkes the Solnum lyopersion speie pproprite for the geneti improvement iming improves the effiieny in the sorption of P. Thus, this reserh ws imed to evlute the development of the root system, gs exhnge nd effiieny for sorption of phosphorus in ontrsting tomto genotypes under phosphorus strvtion. Results Modifitions on root hrteristis It ws oserved tht the root morphology of Gloonnie genotype (Fig. ) hd higher root length vlue in. mg L - of P (Fig. A), when ompred to other tomto genotypes (-9 nd F ). However, with the inresing of P levels, it ws oserved tht the length of roots ws greter in genotypes F (Fig. A). This superiority with the inresing of P levels of F my e explined y the gene intertion in genotypes Gloonnie nd -9. For the root surfiil re (Fig. ) under P limiting ondition of. mg L - P, Gloonnie ws higher ompred to others (-9 nd F ). However, with inresing the P levels, the genotypes Gloonnie nd F showed higher vlues, when ompred to -9, whih is sensitive to lk of P. For the root volume (Fig. C) we oserved the sme tendeny to the Gloonnie for greter prodution of root volume t the lowest level. mg L - of P, onsidering this P onentrtion s limiting for tomto ultivtion. These results onfirm tht the gene of Gloonnie is expressed further under P limittion to tolerte the limiting ftor, ompred with the F nd -9, for the sme tretment. Moreover, with inresing of P levels, the F nd Gloonnie showed higher root volume, when ompred with -9. The root medium dimeter (Fig. D) t. mg L - of P ws higher in -9 thn Gloonnie nd F. However, t the highest level ( mg L - of the P) Gloonnie presented superior thn F nd -9. For the fineness of root (Fig. A) t. mg L - P the genotypes Gloonnie nd F were higher thn -9. With the inresing of levels up to mg L - P, the F nd Gloonnie were lower to ontrol mteril nd sensitive to the lk of P (-9). Additionlly, only on exess level ( mg L - of P), the F hyrid ws more effiient in produing fine root, when ompred to the -9 nd Gloonnie. For the speifi root length (Fig. ) t. mg L - of P, the Gloonnie ws superior to F nd -9. With the inresing of P level up to 3 mg L -, the F hyrid ws superior to the -9 nd Gloonnie. For the level of nd mg L - P, the F showed superiority to other genotypes. The highest vlue of speifi length ws oserved in the genotype Gloonnie in onditions of phosphorus defiieny t. mg L - level. However, with inresing P levels, the F expressed inrese of this prmeter. For root dimeter reltive to speifi length (Fig. 3) it ws shown tht t limiting level (. mg L - of P), the Gloonnie showed superiority ompred to F nd -9 (Fig. 3 A). With proportionl inresing of P levels (Fig. 3 A, nd C) the hyrid vigor of F showed superiority, if ompred with -9 nd Gloonnie. For surfe re of root (Fig. A nd ), Gloonnie (the tolernt genotype to P under. nd 3 mg L - levels of P) ws etter thn F nd -9. However, with inresing of P levels to nd mg L -, the hyrid vigor of root ws expressed higher in F thn Gloonnie nd -9 (Fig. C nd D). These results re very importnt for seletion of tolernt genotypes for P limittion in soils tropilized ountries. The -9 is onsidered sensitive to the lk of P, whih only presents superior with inrese in onentrtion P solution. For volume of root (Fig. A,, C), the Gloonnie genotype ws higher thn F nd -9 t levels of., 3 nd mg L - of P. Only t highest onentrtion of P tht hyrid vigor ws expressed in F to root volume reltive to root dimeter, proving tht the Gloonnie is expressing t root the lrger re to result in greter effiieny in lk of P. Noting tht t ll onentrtions the genotype -9 showed the lest surfe re of fine roots. Reltive to volume y dimeter lsses, the genotype Gloonnie presented, under lk P, the greter volume of fine roots nd redution for thik roots. Moreover, the genotype -9 produe greter mount of thik roots, only responsile for supporting nd fixing of plnt. In short, Gloonnie showed greter length, volume nd surfe re of fine roots nd higher speifi length nd thikness roots. However, reltive the root struture of fine roots, whih is importnt in sorption of P vlues were elow (Fig. ). The dry mtter of lef (Fig. ) ws greter in Gloonnie t lowest level of P (. mg L - ) when ompred to F nd - 9. The F hyrid ws superior in prodution of lef with the inresed P level up to 3 mg L - when ompred to -9 nd Gloonnie. However, t the optiml level ( mg L - of P) nd the exess level ( mg L - of P) no signifint differene ws oserved etween the F, -9 nd Gloonnie genotypes. The prodution of stem ws superior in Gloonnie t. mg L - of P, ompring to other genotypes. Applying the mximum level of P ( mg L - ), the -9 ws superior to F nd Gloonnie. However, the dry mtter of root ws superior in Gloonnie t mg L - of P. With the exess P level ( mg L - of P) -9 ws superior to the other genotypes (F nd Gloonnie). It ws oserved tht P defiieny used redution in dry mtter, pereiving tht the genotype Gloonnie produed more roots thn lef re uder P defiieny (Fig. A, nd C). Genotype responses linked to lef gs exhnge The photosynthesis level ws higher in Gloonnie t the limiting P (. mg L - ) (Fig. 7) ompred to F nd -9. At the 3 mg L - of P the F exhiited superior photosyntheti

3 Root length (m) F Gloone A F Gloone 3 3 Root superfiil re (m ) Root volume (m 3 ) 3 C D.... Root medium dimeter (mm) Phosphorus onentrtion (P Phosphorus onentrtion (P O mg L - O mg L - ) ) Fig. Length (A), surfe re (), volume (C) nd verge dimeter (D) in tomto genotypes (Gloonnie, -9 nd F ) sujeted to different phosphorus onentrtions (.; 3; nd mg L - ). F Gloone A Fineness root (m m 3 ) 7 3 Speifi root length (m g) Phosphorus onentrtion (P O mg L - ) Fig. Fineness root (A), speifi root length () in tomto genotypes (Gloonnie, -9 nd F ) sujeted to different phosphorus onentrtions (.; 3; nd mg L - ). 3

4 Root length (m) (A) Gloonnie F Root length (m) 3 3 () Gloonnie F (C) Gloonnie F (D) Gloonnie F Root length (m) Root length (m) Root dimeter (mm) Root dimeter (mm) Fig 3. Root reltive length under. (A); 3 (); (C) nd (D) (mg L - ) into root dimeter of tomto genotypes (Gloonnie, -9 nd F ). Root superfiil re (m ) Root superfiil re (m ) (A) (C) 9 Gloonnie F () Gloonnie F Root superfiil re (m ) 7 3 Gloonnie F (D) Gloonnie 9 Gloone F Root superfiil re (m ) Root dimeter (mm) Root dimeter (mm) Fig. Root reltive superfiil re under. (A); 3 (); (C) nd (D) (mg L - ) into root dimeter of tomto genotypes (Gloonnie, -9 nd F ). 7 3

5 rte. This is still onsidered s limiting P level reommended for tomto ulture. However, with inresing the level to nd mg L - the superiority of P Gloonnie ws expressed in most photosyntheti rte ompred to F hyrid nd - 9. The rte of lef trnspirtion (Fig. 7 ) ws higher in Gloonnie with inresing the P level, ompred to F nd -9. However, the stomtl ondutne (Fig. 7 C) in lef ws noted independent of P. The stomtl ondutne of Gloonnie inresed with inresing levels of P, showed superiority to F nd -9. It is oserved tht the higher photosyntheti rtes, stomtl ondutne nd trnspirtion our t higher onentrtions of pplied phosphorus. We noted tht Gloonnie showed etter results t different onentrtions of phosphorus, when ompred with the other genotypes of tomto (-9 nd F ). Interestingly, the Gloonnie expressed tolerne trit to the defiit of phosphorus hving the highest rtes of photosynthesis, trnspirtion nd stomtl ondutne t lower onentrtion of phosphorus, showing its superiority in metoli tivity eing possile dpttion of the plnt to limited mount of phosphorus. Conentrtion nd sorption of phosphorus in plnt tissue The P onentrtions in the lef, stem nd root of tomto genotypes re presented in Fig A, nd C, eing desried the higher P onentrtion in leves of Gloonnie under P onentrtion of. mg L - of (Fig. A). However, the inresed P onentrtions produed different ehviors in the genotypes. After 3 nd mg L - P pplition, the phosphorus onentrtions were higher in F ; however, t mg L - P it ws highest in Gloonnie. The P onentrtion in stem (Fig. ) ws higher in Gloonnie t the 3 nd mg L - of P. The P onentrtion ws higher in root of Gloonnie (Fig. C) under. mg L -, ompored to other genotypes. With inrese of P level to mg L -, the Gloonnie nd F genotypes showed higher vlues thn other tomto genotypes. The effiient sorption of phosphorus (EAP) of genotypes nd phosphorus levels re shown in Fig. 9. The EAP of leves (Fig. 9 A) ws higher (effiient) in Gloonnie under. mg L - P, ompred to others. At onentrtions of nd mg L - P, the Gloonie ws more effiient in use of this minerl. For the EAP in stem (Fig. 9 ), Gloonnie lso hd higher effiieny thn other genotypes t the lowest P level. With inresing onentrtions to 3, nd mg L - of P, genotypes showed differentil EAP espeilly -9 with the highest effiieny. For the EAP of roots (Fig. 9 C), the genotype -9 presented more effiieny under onentrtions of nd mg L - P. This greter effiieny of -9 in root my e ssoited with the genotype tht present thiker root, when ompred to the root Gloonnie, whih is hrterized y the prodution of fine roots (Fig ). Disussion All three evluted root hrteristis (length, surfe re nd totl volume) re importnt for phosphorus uptke. The root morphology ends up hving lot of importne on the effiient quisition of phosphorus y plnts euse there is reltive immoility of P tht mkes their quisition dependent on the further exploittion of the soil y the roots (greter length, volume nd root surfe re) (Rmekers et l., ). Previous studies of the tomto hve identified greter effiieny in the sorption of phosphorus. Hohmuthet l. (9) identified different groups of genotypes involving more thn essions of tomto (Solnum lyopersion), t lest two highly effiient genotypes in P extrtion from poor nutrient solution in this nutrient. In one of these introdutions (Gloonnie genotype), the extrtion effiieny of phosphorus ws ssoited with morphologil hrteristi ssoited to the roots when it ws grown in nutrient solution with low levels of P. This hrteristi, lled "ottony root", proved simple inheritne ( reessive gene, referred to s CRT), nd is ssoited with numer of roots, whih n e oserved under mirosope fter stining with eti rmine when plnts re grown in solutions with low level ( ppm) of P (Hohmuth et l., 9). This result ws not oserved when higher onentrtions of P ( ppm) were used (Hohmuth et l., 9). Imd et l. () stted tht the surfe re of the root is more relted to the sorption of nutrients euse lrger surfe re n help plnt to otin soures of nutrients tht re defiient. Also n inrese in the volume of roots when the nutrient onentrtion is the sme throughout the root surfe n led to greter effiieny of nutrient sorption (Cost et l., ). In n unfvorle environment, is importnt for root growth (tht the soil e explored) without loss in fertiliztion (Ryser, ). Theoretilly, higher speifi root length is refleted in further explortion nd quisition of wter nd nutrients in the soil per unit of ron invested (Rmekers et l., ). Therefore, the roots of tomto plnts hve lower expense of liner onstrution (grms ron/length), euse they presented greter speifi length. On the other hnd, inresing the thikness of the root reflets greter explortion of the soil y funtionl roots, euse the effiieny of the roots with high vlues of speifi length n vry etween speies, possily euse the very fine roots hve redued longevity, whih my hinder root funtioning. Thus, seprting speifi length in thik root omponent (length/volume) nd density of tissue roots (root mss /volume) n provide informtion on the reltionship etween root hrteristis nd development strtegies of plnts (Ryser nd Lmers, 99). One of the mjor hnges in plns for the quisition of phosphorus-defiient soils is to inrese the exploittion of the soil through inresed root growth nd prolifertion, minly of those roots metolilly responsile for this funtion (roots of smller dimeter) (Zhng et l., ). Root growth, with minly very fine roots oserved in genotype Gloonnie, n e onneted to this root explortion in serh of greter phosphorus quisition. One of the possile resons tht tomto genotypes hve shown greter length, surfe re nd volume of fine roots (Fig. 3) is fvoring the explortion nd quisition of wter nd nutrients, euse the fine roots hve n importnt role in these funtions (Eissenstt et l., ). In ontrst, signifint differenes etween genotypes (tolernt nd non-tolernt) on the umultion of dry mtter in response to P defiieny hve een reported for the mize rop (Li et l., 7). Furthermore, the inrese of the dry mss of roots y dry mss of the eril prt hs een demonstrted s mjor strtegy in stress tolerne y phosphorus (Nielsen et l., ). Root growth is less ffeted in phosphorus defiient plnts thn the eril prt, often resulting in n inrese in root dry mss/eril prt. This inrese in the rtio of root/eril prt in plnts defiient in phosphorus is orrelted with n inrese in rohydrte prtitioning in root, indited

6 Root volume (m 3 ) Root volume (m 3 ) 3,,,,,,, (A) (C) Gloonnie F Root volume (m 3 ) () Gloonnie F (D) Gloonnie F Root dimeter (mm) Root dimeter (mm) Fig. Root reltive volume under. (A); 3 (); (C) nd (D) (mg L - ) of phosphorus in tomto genotypes (Gloonnie, -9 nd F ). Root volume (m 3 ) Gloonnie F y shrp inrese in surose ontent in roots (Mrshner, 99). The plnts well supplied with phosphorus stok store the exess inorgni phosphorus (Pi) in ells ( to 9%) minly in the vuole or non-metoli mnner of storge. This vuolr Pi is used to mintin the levels of ytoplsmi Pi, whih my hnge due to different metoli tivities nd / or the vrition in the externl supply mens (Jin et l., 7). The Pi sored y plnts n remin in its inorgni form or n e inorported into orgni moleules, suh s the formtion of simple phosphte ester or y inding to other Pi y onneting with energy, forming pyrophosphte, suh s the exmple of the ATP moleule. riefly, the phosphor (P) is involved in severl ellulr roles. It ts s struturl element of moleules suh s nulei ids, proteins, oenzymes; prtiiptes in ellulr proesses suh s energy storge nd trnsfer, ell division nd growth; hs regultory funtion of metoli pthwys in the ytoplsm nd in hloroplsts, ting diretly in the proesses of photosynthesis nd respirtion (Mrshner, 99). For gs exhnge, it ws noted tht Gloonnie presented higher vlue. Phosphorus is onneted, or regultes the iosynthesis of strh/surose, regultes the tivtion of RUISCO nd the provision of energy y ATP in the Clvin yle. In this mnner smller mount of phosphorus leds to n inhiition of these proesses. Tolernt genotypes s Gloonnie hve higher photosynthesis t low onentrtions of P. Silv et l. () oserved derese in stomtl ondutne of offee plnts under onditions of phosphorus defiieny. This ourred when ompring the highest onentrtions of P with the smllest, yet Gloonnie kept higher ondutne ompred to the other genotypes t low P onentrtions, filitting gs exhnge. In the photosyntheti pprtus, phosphte plys regultory role in strh/surose iosynthesis nd RUISCO tivtion, nd role in metolites s it is used to phosphorylte intermedites of the Clvin Cyle, nd in energy vilility (ATP nd NADPH) (Swd et l., 99). P limittion my ffet photosynthesis through hnges in the tivity of Clvin yle enzymes, RuP regenertion, nd/or RUISCO tivity (Jo nd Lwlor, 99). As with nitrogen, feedk limittion of photosynthesis hs een suggested s use of deresed CO t low P supply (Pieters et l., ). However, for tomto plnts, derese in strh umultion with deresing P supply suggested tht the prodution, rther thn the utiliztion of photosynthtes, ws limiting (De Groot et l., ). Phosphorus defiieny in tomtoes leds to deresed gs exhnge prmeters (photosynthesis). In tomto ultivr (Solnum lyopersion. v. Cpit), De Groot et l. (3) oserved tht phosphorus defiieny ffets the pity of roxyltion of CO nd thus dereses the pity to produe photo-ssimiltes. Mterils nd Methods Experiment loliztion nd limti onditions The experiment ws onduted in greenhouse in 3 in the Deprtment of Soil Siene t the Federl University of Lvrs-MG, rzil. The limte is Cw, ording to Köppen, nd hrterized y men nnul ir temperture of.9 Fhrenheit, verge reltive humidity of 7.% nd rinfll 9.7 mm.

7 Dry mtter leflet (g) Mss of stem dry mtter (g) Mss of root dry mtter (g) 3 3 F F Gloone. 3 Phosphorus onentrtion (P O mg L - ) Fig. Root dry mtter (A), stem dry mtter () nd lef dry mtter (C) in tomto genotypes (Gloonnie, -9 nd F ) sumitted to different phosphorus onentrtions (.; 3; nd mg L - ). Plnt mteril Three tomto genotypes differing in phosphorus uptke effiieny were used, eing one effiient in soring phosphorus lled Gloonnie or PI (effiient, rt/rt), nother genotype onsidered sensitive in phosphorus uptke lled -9 (norml, rt + /rt + ) nd F. This genotype ws reted from ross etween Gloonnie (effiient, rt/rt), nd the ommeril strin -9 (rt + /rt + ). All three genotypes were evluted in hydroponi system (Mrques et l., 7) under different phosphorus levels. Growth onditions of genotypes The seedlings were produed in phenoli fom tht remined in the nursery for 3 dys, fter whih they were trnsplnted into plsti ontiners for the ple definitive. In these C A P n (µmol CO m s - ) E (mmol m - s - ) G s (mmol m - s - ) 3 F Gloone Phosphorus onentrtion (P O mg L - ) Fig 7. Photosynthesis (A), trnspirtion () nd stomtl ondutne (C) in tomto genotypes (Gloonnie, -9 nd F ) sumitted to different phosphorus onentrtions (.; 3; nd mg L - ). strutures, supporting stnds were mounted for the first dys fter trnsplnttion. The tomto seedlings were mintined in five different kinds of nutrient solutions vrying only in the phosphorus onentrtion, whih ws pled in plsti ontiners (virgin polypropylene) with pity of L. The onentrtion ws diluted to. of tht reommended y the previous reserhers. After this dpttion period, the plnts were sumitted to fully onentrted solutions until dys fter trnsplnt. The solutions were renewed every dys. It is noteworthy tht, for the mngement of nutrient solutions long the study period, the ph ws monitored dily, djusting to. ±. using NOH or HCl. M L - solution. The eletril ondutivity of the nutrient solutions ws in the rnge of. ds m - nd did not vry mong the exhnge period ( dys), inditing tht the exhnge of nutrient solution every dys ws suffiient to mintin the A C 7

8 Lef P onentrtion (g) Stem P onentrtion (g) Root P onentrtion (g) F Gloone. 3 Phosphorus onentrtion (P O mg L - ) Fig. Phosphorus onentrtion lef (A), stem (), root (C) in tomto genotypes (Gloonnie, -9 nd F ) sumitted to different phosphorus onentrtions (.; 3; nd mg L - ). A C P effiieny leflet (mg) P effiieny stems (mg) P effiieny root (mg) 3 F Gloone. 3 Phosphorus onentrtion (P O mg L - ) Fig 9. Phosphorus sorption effiieny in lef (A), stem (), root (C) in tomto genotypes (Gloonnie, -9 nd F ) sumitted to different phosphorus onentrtions (.; 3; nd mg L - ). A C eletril ondutivity of. ds m -. Distilled wter ws used for the replement of the solution, with n oxygented nutrient solution, nd onstntly renewed every dys. Applition of stress nd experimentl design The experimentl design ws ftoril design onsisting of three genotypes (Gloonnie, -9 nd F ) omined with four phosphorus levels (.; 3; nd mg L - P O ), omposed y four replitions. The nutrient solution ontining ppm of P ws lulted s reommended y Mores nd Furlni (999). However, the solution defiient in P with. mg ws mde ording to Hohmuth et l. (9), whih ws used y reserhers for trige of tomto for effiieny in P uptke nd P defiient solution with. mg P (Mrques et l., 7). In this experimentl stge, plnts were ultivted hydroponilly for eh type of nutrient solution s the onentrtion of P. Anlysis of root system morphology nd dry mtter hrteristis The experiment ws hrvested t dys fter trnsplnting. For the nlysis of the root system, entire plnts were olleted (root system nd eril prts). The smples were sumerged in ponds ontining distilled wter for 3 minutes. This ided the proess of wshing the roots. After the wshing proess, the plnts were seprted into root nd shoot. The wshed roots were stored in vils ontining 7% ethnol solution to prevent dehydrtion nd stored in old storge. For nlysis of root system morphology, the system 7 Pro WinRhizo ws used (Regent Instruments, Sinte-Foy, QC, Cnd), oupled with professionl Epson, Expression. XL snner, (Epson Ameri, In., USA) equipped with n dditionl light unit (TPU). A definition of (dpi) ws used for mesurements of root morphology, s desried y oum et l. () nd Cost et l. (). The roots

9 were pled in nryli tu 7.7 inhes wide y. inhes long ontining wter. The use of this essory llowed otining threedimensionl imges, lso voiding the overlpping of roots; redings were mde on four plnts per genotype. Then, the hrteristis were determined s follows: length, surfe re, volume nd verge dimeter for tomto genotypes. To determine the dry weight of tomto plnts, root, stem nd lef were olleted. The roots were seprted from eril prts, through ut in the plnt lp, wshed with running wter to remove impurities. All omponents were dried in n oven t ºC, with fored ventiltion, until onstnt mss. Other ttriutes involving morphologil nd dry mss dt were s follows: speifi root length (reltionship etween length nd m g) nd root fineness (reltionship etween length nd root volume m m -3 ). Lef gs exhnge For the determintions of gs exhnge, mesurement t 7 dys ws performed fter trnsplnt using portle photosynthesis system (IRGA, Model LI-XT, Li-Cor, Linoln, Ners, USA). All mesurements were performed in the morning etween 9: m nd : m on fully expnded terminl lef. The prmeters mesured were lef photosynthesis (P n ), stomtl ondutne (gs), nd trnspirtion rte (E). Mesurements were mde on lef re of m with flow of ir in the hmer with CO onentrtion of 3 µmol mol -. The ir ws olleted outside the greenhouse nd trnsported into protetive gllon nd then pumped into the hmer. One photon flux density (PPFD) of µmol m - s - of light soure red-lue LED ws used. Other environmentl ftors suh s ir humidity nd temperture were not ontrolled llowing for nturl vrition. Nutritionl determintion in tissues Smples of root, stem nd the lef were nlyzed for minerl omposition to dys fter plnting. The nlyses were onduted in the lortory of minerl nutrition of plnts, Deprtment of Soil Siene-UFLA methodologies s desried y Mlvolt et l. (997). Asorption effiieny of phosphorus The sorption effiieny of P is defined s the produt of effiienies of quisition nd internl use of P, orresponding to the dry mss of the lef, stem nd roots produed y. l of phosphorus (Moll et l., 9). Sttistil nlysis Dt were sujeted to vrine nlysis nd when signifint differenes ourred; Sott-Knott test t % level of error proility ws pplied (Steel et l., ). Stndrd errors were lulted for ll mens. All sttistil proedures were rried out with the SAS softwre (SAS, 99). Conlusion sed on this reserh, it n e onluded tht the Gloonnie genotype showed superiority in root hrteristis, gs exhnge nd effiieny in the phosphorus sorption onsidering tht the gene ottony root ws expressed in the genotype. Gloonnie nd F presented etter performnes under phosphorus strvtion, sed in root hrteristis nd gs exhnge tht promote higher P effiieny, esides improving the uptke nd use of the phosphorus. Therefore, this reserh revels possiility of redution of phosphorus pplition nd onsequent redution of osts linked to tomto prodution. Aknowledgments This reserh ws finnilly supported y Conselho Nionl de Desenvolvimento Científio e Tenológio (CNPq/rzil), Fundção de Fundção Amzôni Prense de Ampro à Pesquis (FAPESPA) nd Universidde Federl Rurl d Amzôni (UFRA) to Loto AKS nd Mrques DJ. Referenes Alvrez JM, Roh JF, Mhdo SR () ulliform ells in Loudetiopsis hrysothrix (Nees) Conert nd Tristhy leiosthy Nees (Poee): struture in reltion to funtion. rz Arh iol Teh. :3-9. Jin A, Poling DM, Krthikeyn SA, lkeslee JJ, Wendy PA, Titpiwtnkun, Murphy SA, Rghothm GK (7) Differentil effets of surose nd uxin on lolized phosphte defiieny-indued modultion of different trits of root system rhiteture in Aridopsis. Plnt Physiol. :3-7. oum TJ, Nielson LK, Koutstl SA () Smple preprtion nd snning protool for omputerized nlysis of root length nd dimeter. Plnt Soil. :- 9. Cost CLM, Dwyer X, Zhou P, Dutilleul C, Hmel ML, Reid LD () Root morphology of ontrsting mize genotypes. Agron J. 9:9-. De Groot CC, Mrelis MFL, Vn Den oogrd R, Kiser MW, Lmers H (3) Intertion of nitrogen nd phosphorus nutrition in determining growth. Plnt Soil. :7-. De Groot CC, Mrelis MFL, Vn Den oogrd R, Lmers H () Growth nd dry mss prtitioning in tomto s ffeted y phosphorus nutrition nd light. Plnt Cell Environ. : Eissenstt DM, Wells EC, Yni DR () uilding roots in hnging environment: implitions for root longevity. New Phytol. 7:33-. FAO () Food nd griulture orgniztion of the United Ntion. In: FAO sttistil dtse,. Filgueir FAR, Oeid CP, Mris JH, Sntos VW, Fontes RR (999) Stked tomto. In: Rieiro CA, Guimrães GTP, Avrez HV (Eds). Reommendtions for the use of lime nd fertilizers in Mins Geris, th Approh. CFSEMG, Viços, 7-. Hohmuth GJ, Gelmn HW, Gerloff CG (9) The gene ffeting tomto root morphology. Hortsiene. :99-. Imd S, Ymnk N, Tmi S () Wter tle depth effets Populus l fine root growth nd whole plnt iomss. Funt Eol :-. IGE (3) rzilin Institute of Geogrphy nd Sttistil. In: Systemti survey of griulturl prodution. Aville in: Jo J, Lwlor WD (999) Dependene of photosynthesis of sunower nd mize leves on phosphte supply, riulose-,-iphosphte roxylse/oxygense tivity nd riulose-,-isphosphte pool size. J Plnt Physiol. 9:-7. 9

10 López-uio J, Cruz-Rmirez A, Herrer-Estrel L (3) The role of nutrient vilility in regulting root rhiteture. Curr Opin Plnt iol. :-7. Lynh J (99) The role of nutrient effiient rops in modern griulture. J Crop Prod. :-. Kohin LV, Hoenkeng AO, Piñeros AM () How do rop plnts tolerte id soils? Mehnisms of luminum tolerne nd phosphorus effiieny. Ann Rev Plnt iol. :9-9. Mrshner H (99) Minerl nutrition in plnts nd edn. Ademi Press, Sn Diego. Mrques DJ, Silv EC, Mores LFR, Cetno E, Silv AR, Arújo HT, Areu MV, Miel AMG (7) Introgression of resistne nd hrteriztion of the gene phosphorus defiieny in tomto. In: IV rzilin Congress of Plnt reeding. Summries.São Lourenço, rzil: AMP (CD- ROM). Mlvolt E, Vitti CG, Oliveir AS (997) Evlution of nutritionl sttus of plnts: priniples nd pplitions. nd edn. Potfos, Piri. Mores CAG, Furlni RP (999) Cultivtion of fruit vegetles in hydroponis in greenhouses. Inf Agrope. :-3. Moll RH, Kmprth JE, Jkson AW (9) Anlysis nd interprettion of ftors whih ontriute to effiieny of nitrogen utiliztion. Agron J. 7:-. Nielsen KI, Eshel A, Lynh PJ () The effet of phosphorus vilility on the ron eonomy of ontrsting ommon en genotypes. J Exp ot. : Rmekers L, Remns R, Ro MI, lir WM, Vnderleyden J () Strtegies for improving phosphorus quisition effiieny of rop plnts. Field Crops Res. 7:9-7. Ryser P () The mysterious root length. Plnt Soil. :-. Ryser P, Lmers H (99) Root nd lef ttriutes ounting for the performne of fst- nd slow-growing grsses t different nutrient supply. Plnt Soil. 7:-. SAS Institute 99. SAS/STAT User s Guid, Version. SAS Institute, Cry. Swd S, Usud H, Tsukui T (99) Prtiiption of inorgni orthophosphte in regultion of the riulose-,- iphosphte roxylse tivity in response to hnges in the photosyntheti soure-sink lne. Plnt Cell Physiol. 33: Silv L, Mrhiori REP, Miel PC, Mhdo CE, Rieiro VR () Photosynthesis, wter reltions nd growth of young offee plnts in reltion to phosphorus vilility. Pesq Agrope rs. :9-97. Silv EC, Mluf RW () Hydroponi tehnique for sreening tomto genotypes on the effiieny of phosphorus uptke. Horti rs. 3:37-3. Stuffer MD, Sulewski G () Phosphorus: Essentil for Life. In: Ymd, T, Adll SRS (Eds.). Phosphorus in rzilin Agriulture. Potáfos, Piri, -. Shröder JJ, Smit LA, Cordell D, Rosemrin A () Improved phosphorus use effiieny in griulture: A key requirement for its sustinle use. Chemosphere. :- 3. Steel RGD, Torrie JH, Dikey DA () Priniples nd proedures of sttistis: iometril pproh, 3 rd edn. Ademi Internet Pulishers, Moorprk. Pieters AJ, Pul JM, Lwlor WD () Low sink demnds limits photosynthesis under Pi defiieny. J Exp ot. :3-9. Yn XL, Lio H, Trull CM, eee ES, Lynh PJ () Indution of mjor lef id phosphtse does not onfer dpttion to low phosphorus vilility in ommon en. J Plnt Physiol. :9-9. Zhng F, Shen J, Zhng J, Zuo Y, Li L, Chen X () Rhizosphere proesses nd mngement for improving nutrient use effiieny nd rop produtivity: implitions for Chin. Adv Agron. 7:-3.