ELECTRICAL CONDUCTIVITY AND SOYBEAN SEEDLING EMERGENCE

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1 Colete et l. ELECTRICAL CONDUCTIVITY AND SOYBEAN SEEDLING EMERGENCE Julio Cesr Fchini Colete ; Robervl Diton Vieir *; Alek Sndro Dutr Prefeitur Municipl - Secretri d Educção, Rod. Rene Vz de Almeid, km, Colin, SP - Brsil. UNESP/FCAV - Depto. de Produção Vegetl, Vi de Acesso Prof. Pulo Donto Cstellne, s/n Joticl, SP - Brsil. *Corresponding uthor <rdvieir@fcv.unesp.br> ABSTRACT: Evlution of soyben [Glycine mx (L.) Merrill] seeds vigor nd its reltion with field seedling emergence cn provide secure indictives of seed physiologicl potentil. The present reserch studied the reltionship between the electricl conductivity test nd the seedling emergence of soyben in field nd lortory. The field experiment ws sown in November th, December td nd th,. Lortory tests were performed using levels of wter potentil in the substrte (soil) -.; -.; -.; nd -. MP. Fourteen seed lots, seven of Embrp nd seven of BRS soyben cultivrs were used. Lortory tests comprised seed wter content determintion, before nd fter the ccelerted ging; germintion nd vigor tests (ccelerted ging nd electricl conductivity). Germintion nd seedling emergence decresed s the substrte wter potentil ws reduced, indicting reltionship mong the germintion, wter potentil nd seed vigor. For the Embrp higher vigor seed lots, the best performnce occurred t -. MP wter potentil. The electricl conductivity test my be efficient to evlute soyben seed vigor nd, consequently, the performnce potentil in the field. However, further studies re necessry to determine the vlues or the rnge of vlues tht indicte the seed vigor level nd the dequte use of given seed lot. Key words: Glycine mx, seed nlysis, wter content, vigor, wter potentil CONDUTIVIDADE ELÉTRICA E A EMERGÊNCIA DE PLÂNTULAS DE SOJA RESUMO: A vlição do vigor e su relção com emergênci de plântuls em cmpo é fundmentl pr estimtiv corret do potencil fisiológico de sementes de soj [Glycine mx (L.) Merrill]. O presente trlho objetivou verificr relção entre os resultdos do teste de condutividde elétric (CE) e os d emergênci de plântuls de soj em cmpo e em lortório. Form estuddos níveis de disponibilidde de águ no substrto -,; -,; -,; e -, MP. Form vlidos lotes de sementes ds cultivres Embrp e BRS. O experimento em cmpo foi conduzido em três épocs de semedur (/ e e // ); em lortório, form determindos o teor de águ, ntes e pós o envelhecimento celerdo (EA) ds sementes, germinção e o vigor (testes de EA e de CE). A redução progressiv d quntidde de águ no substrto provocou diminuição ds porcentgens de germinção e de emergênci de plântuls em lortório, de modo que o desempenho germintivo ds sementes dependeu dos níveis de estresse hídrico e do vigor d semente. Pr lotes de mior vigor d cultivr Embrp, o melhor desempenho ocorreu sob o potencil hídrico de -, MP. CE pode ser um eficiente procedimento pr vlição do potencil fisiológico e desempenho de lotes de sementes de soj, necessitndo, porém, que estudos dicionis sejm conduzidos pr o estelecimento de vlores ou limites de vlores pr crcterizr o nível de vigor ds sementes (lto, médio ou bixo) permitindo direcionr de mneir consistente o uso dos lotes de sementes. Plvrs-chve: sementes, nálise, vigor, teor de águ, potencil hídrico INTRODUCTION Fst evlution of seed physiologicl potentil is n importnt tool for decision mking in different stges of production process, storge nd commerciliztion. Qulity control evolves the seed germintion nd vigor evlution. Vigor tests bsed on the cellulr membrne integrity re relevnt becuse they mke possible detection of initil phses of the seed deteriortion process (Delouche & Bskin, 7). Therefore, technicl mesures cn be tken to reduce or minimize the effect of deteriortion nd the consequent decrese in the seed physiologicl potentil of given seed lot (Dis & Mrcos Filho, ). As much s seed vigor, substrte wter potentil is n ctive gent of the seedling estlishment process in the field. According to Crvlho & Nkgw (), wter is the min fctor on seed germintion. Wter - Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August

2 Electricl conductivity nd soyben seedling emergence 7 sorption promotes tissue re-hydrtion with consequent intensifiction of respirtion nd other metolic pthwys, tht supplies energy nd necessry nutrients for triggering the growth of the embryonic xis. Wter vilility is bsic fctor to seed germintion, nd substrtes should keep enough moisture to gurntee embryo growth. However, excess wter reduces oxygen vilility, nd therefore respirtion, delying or prlyzing seedling development (Mrcos Filho et l., 7). Under wter deficiency, seeds remin longer into the soil, therefore subjected to microorgnisms ttck (Crvlho & Nkgw, ). This work imed to study the reltionship between electricl conductivity nd seedling emergence tests under field nd lortory conditions. MATERIAL AND METHODS Trils were crried out in the lortory nd field experimentl re, t Joticl, Stte of São Pulo, Brzil (º "S; º "W; ltitude. m). Seven soyben seed lots of cultivr BRS nd seven of the Embrp were used. Preliminry evlutions of the seed physiologicl potentil were performed through germintion nd vigor (electricl conductivity nd ccelerted ging) tests. After the preliminry evlutions, nd bsed on the electricl conductivity test, three seed lots of ech cultivr were selected nd clssified s of low (> nd < µs cm - g - ), medium ( - µs cm - g - ) nd high (< µs cm - g - ) vigor, respectively. This clssifiction took into considertion reports of Vieir (), Vieir & Krzyznowski () nd Vieir et l. (). The selected lots were used to study the reltionship between the substrte wter potentil nd seed germintion nd vigor, in lortory experiments using soil with four wter potentils: -.; -.; -. nd. MP. Wter content determintion - Two -seed subsmples from ech lot were weighed to the nerest. g nd oven dried during h t ± C (ISTA, ). Wter content ws determined before nd fter ccelerted ging tests, nd results expressed in the wet bsis. Germintion test - germintion tests were performed with four -seed smples from ech lot, in rolled ppertowel previously moisturized with. times the pper weight. Germintion proceeded in germintor t C nd counts were mde five nd eight dys fter seeding (ISTA, ). Accelerted ging test () - Accelerted ging test ws set using g of seeds from ech lot, distributed over n luminum screen in germintion plstic boxes (. cm). The boxes received ml of distilled wter nd were kept in germintion chmber (BDO type) for Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August hours (Hmpton & TeKrony, ; Mrcos Filho, ). Seeds were then submitted to the germintion test (ISTA, ). Electricl conductivity test (EC) - Four -seed replictions of ech lot were weighed to the nerest. g nd immersed in 7 ml of deionized wter within - ml plstic vils. Seed hydrtion occurred into germintor t C, during hours. After this period EC ws determined in the imbibition s solution with Digimed CD- constnt electrode- conductivimeter, nd results expressed s µs cm - g - (Hmpton & TeKrony, ; Vieir & Krzyznowski, ). Seedling emergence test (SE) - This field experiment ws crried out in n experimentl re of the Crop Production Deprtment: -seed smples of ech lot were mnully distributed in. m long nd. m prt rows t - cm depth. Sowing occurred in November th, nd December rd nd th. Emerged seedling evlution ws mde dys fter sowing (Nkgw, ). Seedling emergence under vrying soil wter potentil - Soil substrte with vrying quntities of wter to provide potentils of.; -.; -. nd. MP were used. The wter volume to give the correspondent wter potentil ws determined from the soil chrcteristic wter retention curve. An eutrophic Rhodic Hpludox ws collected t to cm depth in n re djcent to the field experiment. The soil ws sieved for elimintion of clods nd stored in plstic boxes. Wter content ws determined in four -g smples, oven-dried t ± C for hours. The seedling emergence evlution ws mde with four -seed replictions ech, seeded in plstic boxes (. cm. cm. cm), with. kg of soil. After the initil wter content determintion by the grvittionl method (EMBRAPA, 7), the quntity of wter to be dded to the boxes ws estimted considering the soil wter retention curve for ttinment of the previously estlished potentils (Tle ). The soilwter mixture ws homogenized, so tht humidity ws uniform in ll the substrte volume. The plstic boxes were then covered with blck polyethylene bgs to prevent wter evportion. Twenty four hours lter, germintion boxes were filled with soil nd sowing performed t depth of cm. The wter volume to be dded to ech box (Tle ) ws determined through the following equtions: Q = θ c θ i nd V = [m(q/)]/d where: Q = mount of wter to be dded to the substrte (%); θ c = moisture in volume bse corresponding to the desired wter potentil (%); θ i = initil soil moisture in volume bse (%); V = volume of wter (cm ) to be dded to ech plstic box; m = soil weight (g) in ech plstic box; nd d = soil pprent density (kg dm - ).

3 Colete et l. Tle - Wter volumes used to chieve the four wter vilility levels in the soil substrte. Initil humidity Wter tension % MP Moisture degree in volume bsis H O to be dded H O volume/. kg soil cm - cm % cm L m After sowing, ech box ws wrpped in trnsprent polyethylene bgs ( cm cm. mm) to prevent evportion nd possible ltertions in the soil wter potentils. The plstic bgs were fixed in the box corners with the help of bmboo sticks nd the bgs ends were folded underneth the boxes. This germintion pprtus ws kept under room conditions (- o C) without controlled temperture or ir humidity. Seedling emergence ws evluted ten dys fter sowing, when the considered emerged seedlings showed well chrcterized pprent plumule, cotyledon nd hypocotyl over the soil surfce. At tht time, nongerminted seeds were rotten with fungi myceli on their tegument. RESULTS AND DISCUSSION Initil seed wter content vried from. to.% in Embrp cultivr (Tle ) nd from. to.% in BRS cultivr (Tle ). Presenting similr wter content vlues, is n importnt fctor to run the ccelerted ging nd electric conductivity tests becuse results might be influenced by the seed initil wter content (Hmpton & TeKrony, ; Vieir & Krzyznowski, ; Vieir et l., ). After the ccelerted ging test nd wter content determintion, it ws observed comptible vrition in the results, lower thn to %, which re within the rnge considered dequte by severl uthors (AOSA, ; Hmpton & TeKrony, ; Mrcos Filho, ; Vieir & Krzyznowski, ). Initil seed germintion, in ll lots for the two cultivrs, presented dequte vlues for commerciliztion ( %): - % for Embrp (Tle ) nd - % for BRS (Tle ). The cultivr Embrp (Tle ) ws clssified s of high vigor ccording to both tests (ccelerted ging nd electricl conductivity) (Egli & TeKrony, ; ; Vieir, ; Mrcos Filho, ; Vieir & Krzyznowski, ), once these uthors compred severl experiments. Vigor tests lso shll present reltion with field seedling emergence (TeKrony, ; Mrcos Filho, ). Electricl conductivity tests llowed clssifiction of seeds of both cultivrs in two lots with different vigor levels. Embrp (Tle ) showed vrition from 7 to µs cm - g - nd BRS (Tle ) from 7 to µs cm - g -. Soyben seed lots with EC within the limits of to 7 µs cm - g - re considered of high vigor nd between 7 to µs cm - g - re considered of medium vigor (Vieir, ). In generl, the higher the mount of ions relesed to the solution, the lower the germintion, so ions relese cn be considered mesure of the physiologicl seed potentil. Testing soyben seeds, Dis & Mrcos Filho () found similr results. Seed lots with EC up to - µs cm - g - my present stisfctory field performnce if environmentl conditions re dequte (Piv Aguero et l., 7; Vieir et l., ; b). Vigor tests hve been used s complementry informtion to the germintion test. They re considered efficient to clssifiction of seed lots ccording to physiologicl potentil, but it is lso desirle tht they provide coherent results with field seedling emergence. The polynomil regression clculted for field seedling emergence (FSE) nd electricl conductivity Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August

4 Electricl conductivity nd soyben seedling emergence Tle - Seed wter content vlues (SWC), stndrd germintion test (SG), nd seed vigor evluted by the ccelerted ging () nd electricl conductivity (EC) tests of seven soyben seed lots of Embrp cultivr. Seed lots Initil SWC After % µ S cm - g.. c 7.. c.. 77 c bc c.. bc c b 7 c. **. **. ** by Tukey test ( α =.) CV (%).. 7. *Mens followed by the sme letters in the column do not differ by Tukey test (α =.). Tle - Seed wter content vlues (SWC), stndrd germintion (SG), nd seed vigor evluted by the ccelerted ging () nd electricl conductivity (EC) tests of seven soyben seed lots of BRS cultivr. Seed lots Initil SWC After SG SG Vigo r Vigo r % µ cm EC EC S - g -.. c c 7 c.. 7 bc bc.. c 7 bcd 7 c.. c 7 d cd.. c 7 c 7.. c 7.7 **.7 **.7 ** by Tukey test ( α =.) CV (%). 7.. *Mens followed by the sme letters in the columns do not differ by Tukey test (α =.). (EC) for Embrp e BRS cultivrs re presented in Figures nd. Field seedling emergence incresed s EC vlues decresed; this confirms results obtined by Vieir et l. () with soybens. According to results of FSE nd EC vigor tests, the seven seed lots of BRS showed vrying vigor, nd in lower scle thn those observed for Embrp. Seed lot number in the first sowing nd seed lots, nd 7 from the second sowing (Tle ) of Embrp hd lower field seedling emergence thn other seed lots. However no significnt effects were observed. Seed lots nd from first nd second sowing nd seed lot from third sowing of BRS (Tle ) presented lower field seedling emergence thn other seed lots. The reltion between results of FSE nd EC indictes tht the ltter cn estimte with precision seedling performnce in the field, depending upon previling environmentl conditions during sowing nd seed lot vigor (Vieir et l., ; b). Wter vilility ffected seed germintion in the vrying soil wter potentil lortory test. The observed vrition ws dependent on wter stress nd seed vigor (Figures e ). Best results were observed for. nd. MP nd the worst for. nd. MP, probly becuse of wter excess or deficit, respectively. At the. nd. MP wter potentil both cultivrs presented similr performnce. High physiologicl potentil (germintion nd vigor) of given seed lot credentiled it for superior performnce in brod rnge of field environmentl conditions (Egli & TeKrony, ; Mrcos Filho, ). The reltionship between results of electricl conductivity tests nd seedling emergence in the field nd lortory vried with wter vilility nd seed vigor; Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August

5 Colete et l. Electricl Conductivity (µs cm g ) y = -.x +.x R = Seedling Emergence (%) Figure - Regression eqution for the electricl conductivity test nd field seedling emergence of the Embrp cultivr. Electricl Conductivity ( µ Scm g - ) y = -.x + 7.x -. R = Figur - Regression eqution for the electricl conductivity test nd field seedling emergence of the BRS cultivr. Seedling emergence (%) 7 7 Seedling Emergence (%) Figure - Regression eqution for the lortory seedling emergence of seven seed lots of BRS cultivr, under vried soil substrte wter levels. Seedling emergence (%) 7 y = -.7x +.x +. R = Wter potencil(-mp) y = -.x +.7x +. R = Wter potencil(-mp) Figure - Regression eqution for the lortory seedling emergence of seven seed lots of Embrp cultivr, under vried soil substrte wter levels Tle - Field soyben seedling emergence of seeds originted from the seven lots of Embrp cultivr, in three different sowing dtes. Seed lots Sowing dte % b * ns. ns. by Tukey test ( α =.).7.7. CV(%) Mens followed by the sme letters in the columns do not differ by Tukey test (α =.). Sowing dtes: = Nov./; = Dec./ nd Dec./. Tle - Field soyben seedling emergence of seeds originted from the seven lots of BRS cultivr, in three different sowing dtes. Seed lots Sowing dte % b n s..* ns. by Tukey test ( α =.).7.7. CV(%).7..7 Mens followed by the sme letters in the columns do not differ by Tukey test (α =.). Sowing dtes: = Nov./; = Dec./ nd = Dec./. seedling emergence in the lortory vried with substrte wter potentil. The ove results llow ssociting seed performnce in the field nd results of electricl conductivity tests, since environmentl conditions might be simulted through vritions in wter vilility. Results herein reported confirm those obtined by Vieir et l. (; b) llowing prcticl reltion in the use of EC s vigor test for soyben seeds. As function of test results nd seedling emergence reltionships, inferences cn be mde upon seed performnce potentil nd for wht conditions given seed lot might be recommended. Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August

6 Electricl conductivity nd soyben seedling emergence ACKNOWLEDGEMENTS To the COOPERATIVA AGRÍCOLA DA REGIÃO DE ORLANDIA (CAROL) for the dontion of seed lots nd to CNPq for the scholrship. REFERENCES ASSOCIATION OF OFFICIAL SEED ANALYSTS - AOSA. Seed vigor testing hndbook. Est Lesing: AOSA,. p. (Contribution, ). CARVALHO, N.M.; NAKAGAWA, J. Sementes: ciênci, tecnologi e produção..ed. Joticl: Funep,. p. DELOUCHE, J.C.; BASKIN, C.C. Accelerted ging techniques for predicting the reltive storility of seed lots. Seed Science nd Technology, v., p.7-, 7. DIAS, D.C.F.S.; MARCOS FILHO, J. Testes de condutividde elétric pr vlição do vigor de sementes de soj (Glycine mx (L.) Merril). Scienti Agricol, v., p.-,. EGLI, D.B.; TEKRONY, D.M. Soyben seed germintion, vigor nd field emergence. Seed Science nd Technology, v., p.-7,. EGLI, D.B.; TEKRONY, D.M. Seedbed conditions nd prediction of field emergence of soyben seed. Journl of Production Agriculture, v., p.-7,. EMPRESA BRASILEIRA DE PESQUISA AGROPECUARIA. Mnul de métodos de nálise de solos..ed. Rio de Jneiro: EMBRAPA, CNPS, 7. p. (Documentos, ). HAMPTON, J.G.; TEKRONY, D.M. Hndbook of vigour test methods. Zurich: ISTA,. 7p. INTERNATIONAL SEED TESTING ASSOCIATION. Interntionl rules for seed testing. Seed Science nd Technology, v., p.-,. Supplement. MARCOS FILHO, J. Testes de vigor: Importânci e utilizção. In: KRZYZANOWSKI, F.C.; VIEIRA, R.D.; FRANÇA NETO, J.B. (Ed.) Vigor de sementes: conceitos e testes. Londrin: ABRATES,. cp., p.-. MARCOS FILHO, J.; CÍCERO, S.M.; SILVA, W.R. Avlição d qulidde fisiológic ds sementes. Pircic: FEALQ, 7. p. NAKAGAWA, J. Testes de vigor bsedos no desempenho ds plântuls. In: KRZYZANOWSKI, F.C.; VIEIRA, R.D.; FRANÇA NETO, J.B. (Ed.) Vigor de sementes: conceitos e testes. Londrin: ABRATES,. cp., p.-. PAIVA AGUERO, J.A.; VIEIRA, R.D.; BITTENCOURT, S.R.M. Avlição d qulidde fisiológic de sementes de cultivres de soj. Revist Brsileir de Sementes, v., p.-, 7. TEKRONY, D.M. Seed vigor testing. Journl of Seed Technology, v., p.-,. VIEIRA, R.D. Teste de condutividde elétric. In: VIEIRA, R.D.; CARVALHO, N.M. Testes de vigor em sementes. Joticl: FUNEP,. p.-. VIEIRA, R.D.; KRZYZANOWSKI, F.C. Teste de condutividde elétric. In: KRZYZANOWSKI, F.C.; VIEIRA, R.D.; FRANÇA NETO, J.B. (Ed.) Vigor de sementes: conceitos e testes. Londrin: ABRATES,. cp., p.-. VIEIRA, R.D.; PAIVA AGUERO, J.A.; PERECIN, D. Electricl conductivity nd field performnce of soyben seeds. Seed Technology, v., p.-,. VIEIRA, R.D.; PAIVA-AGUERO, J.A.; PERECIN, D.; BITTENCOURT, S.R.M. Correltion of electricl conductivity nd other vigor tests with field emergence of soyben seedlings. Seed Science nd Technology, v.7, p.7-7, b. VIEIRA, R.D.; PENARIOL, A.L.; PERECIN, D.; PANOBIANCO, M. Condutividde elétric e teor de águ inicil ds sementes de soj. Pesquis Agropecuári Brsileir, v.7, p.-,. Received April, Accepted April, Sci. Agric. (Pircic, Brz.), v., n., p.-, July/August