Copper supply and fruit yield of young Citrus trees: fertiliser sources and application methods

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1 DOI: SOIL AND PLANT NUTRITION - Note Copper supply nd fruit yield of young Citrus trees: fertiliser sources nd ppliction methods Frnz Wlter Rieger Hippler 1, Rodrigo Mrcelli Boretto 1 *, Luiz Antonio Junqueir Teixeir 2, José Antonio Quggio 2, Dirceu de Mttos-Jr 1 1.Instituto Agronômico - Centro de Citricultur Sylvio Moreir - Cordeirópolis (SP), Brzil. 2.Instituto Agronômico - Centro de Solos e Recursos Agromientis - Cmpins (SP), Brzil. ABSTRACT: This study imed to evlute the fertiliser sources nd ppliction methods of copper (Cu) in citrus trees during the first yers of fruit production. Two experiments were set up in n orchrd with 3-yer-old sweet ornge trees, which were pplied with three sources of Cu (nitrte, sulfte or ) either vi fertigtion (Experiment 1) or vi folir sprys (Experiment 2). Regrdless of the fertiliser source, Cu ppliction vi fertigtion ws not efficcious to increse the micronutrient concentrtion in leves nd, consequently, did not ffect fruit yield. Conversely, folir ppliction of Cu, either s nitrte or sulfte, incresed this nutrient level in leves ut when pplied s copper nitrte, visul phytotoxicity symptoms were verified in leves due to slt ccumultion in the plnt cnopy, which reduced the fruit yield. Considering the plnt growth nd intensified phytosnitry mngement of the orchrd with the ppliction of coppersed products fter the third yer of the experiment, the effects of Cu tretments on fruit yield re expected to e negligile s the trees ge. Key words: micronutrient, nutritionl sttus, fertigtion, folir ppliction, citriculture. *Corresponding uthor: oretto@ccsm.r Received: Apr. 11, 217 Accepted: Jul. 17, 217 Brgnti, Cmpins, v. 77, n. 2, p ,

2 F.W.R. Hippler et l. The demnd for micronutrients y citrus trees increses in high yielding orchrds. In this context, gins in fruit yields re possile in production systems tht include (i) dvnced soil mngement strtegies for orchrd estlishment; (ii) improved tree plnting densities; nd djusted (iii) phytosnitry mngement; (iv) fertilistion s function of cnopy nd rootstock comintion, nd (v) nutrient doses pplied in non-irrigted or irrigted res (Mttos Jr. et l. 21; (Mttos Jr. et l. 217). Copper (Cu) deficiency in citrus is commonly oserved in non-ering trees, during the first yers fter orchrd estlishment due to the increse in plnt vigour y pplictions of high rtes of nitrogen-contining fertilisers, s well s y the low ppliction of copper-sed pesticides (Mttos Jr. et l. 21; Hippler et l. 216; Hippler et l. 217). Visul symptoms of Cu deficiency re chrcterised y plnt growth with less lignified tissues of new plnt prts, enlrged nd S-shped twigs nd over-developed lef ldes with protruding veins on the underside (Cmp 1938). Folir ppliction is the min method used to supply metl micronutrients [Cu, mngnese (Mn) nd zinc (Zn)] in citrus. Such ppliction is necessry, due to the low moility of these nutrients in the phloem of every new vegettive flush nd, consequently, their poor redistriution through the plnt (Boretto et l. 23; Hippler et l. 216; Hippler et l. 217). Conversely, micronutrient ppliction vi fertigtion cn e split into severl doses, which llows deficiencies or nutritionl excesses in the orchrds to e corrected during the plnt growth (Zekri nd Koo 1992). Additionlly, under tropicl soil conditions, the prctice of fertigtion enhnces soil cidifiction in the wetting ul, which likely increses the vilility of Cu in the soil solution nd fvours the sorption of the metl y roots (Quggio et l. 21). Therefore, knowledge out the most pproprite fertiliser source nd the ppliction method re importnt to increse the efficiency of Cu utilistion nd, hence, mximise the development nd production of citrus. This study imed to evlute the effects of ppliction methods nd Cu fertiliser sources on the nutritionl sttus nd fruit yield of young citrus trees. Therefore, two experiments were performed in commercil orchrd of sweet ornge trees [Citrus sinensis (L.) Os. Per ] grfted onto Sunki mndrin (C. reshni hort. ex Tnk) nd fertigted y single drip line with.6 m spced drippers nd flow rte of 7.l L h 1. Irrigtion ws scheduled every 2 dys nd the mount of wter pplied ws determined y mesuring the evportion using Clss A pn, the potentil evpotrnspirtion nd the crop evpotrnspirtion otined, ccording to Allen et l. (1998). The orchrd ws plnted t m, in totl of 493 trees.h 1, locted in Colômi-SP (lt S, long W; ltitude of 56 m ove se level), in sndy lomy soil (19.7% cly, 4.% silt nd 76.3% snd), ph (CCl 2 ) 5.1, 68.5 mmol c.dm 3 ction exchnge cpcity (CEC), nd contining 23.5 g.dm 3 of orgnic mtter nd 4.4 mg.dm 3 Cu (DTPA-TEA ph 7.3) (Areu et l. 1998). Adsorption curves for Cu in the soil were performed, ccording to Hippler et l. (214), sed on the Lngmuir dsorption isotherm (Brdl 24). The soil exhiited mximum 73.1 mg.kg 1 dsorption cpcity ( L ) nd inding energy (K L ) of.37 L.kg 1. The locl climte is clssified s Aw ccording to Ko ppen, with hot nd humid summer nd dry winter with verge nnul temperture of pproximtely 23 C. The experimentl tretments consisted of three fertiliser sources contining Cu [Cu(NO 3 ) 2, CuSO 4 5H 2 O or Cu- (C 1 H 14 CuN 2 O 8 )], which were pplied either vi fertigtion (Experiment 1) or folir sprys (Experiment 2). A Control tretment, common to oth experiments, consisted of zero Cu ppliction. Two yers fter eginning the study, phytosnitry mngement of the citrus orchrd with copper-sed pesticide sprys (Behlu et l. 217) ws conducted in ll the experimentl re. The experiments were estlished in rndomised lock design, with four tretments nd five locks, with one replicte per tretment in ech lock. Individul plots comprised line of 16 trees, with the 1 centrl trees considered for evlution of tretment effects. Both experiments were done in the sme re nd the Cu tretment pplictions strted in the third yer fter the orchrd estlishment. The experimentl evlutions were performed in the following three yers. Copper pplictions in ll tretments (except the Control trees) totlled 5 kg.h 1.yr 1 of Cu. In Experiment 1, the Cu sources were pplied vi fertigtion in totl of 2 pplictions per yer (.4 kg.h 1 of Cu per ppliction), etween August (lte Fll) nd April of the susequent yer (Summer). In Experiment 2, the pplictions were performed in the sme period s the first experiment ut with 4-5 folir sprys per yer ( kg.h 1 of Cu per ppliction), ccording to Quggio et l. (21). Orchrd fertilistion, with the exception of Cu, followed the recommendtions of Quggio et l. (21). 366 Brgnti, Cmpins, v. 77, n. 2, p , 218

3 Copper supply nd fruit yield of Citrus For oth experiments, soil nd leves were smpled every yer y the end of the Summer (Mrch-April). In the 3 yers of experimentl evlutions, soil smples were collected from the - 2 cm soil depth lyer. Additionlly, in the first nd third yers, such smples were lso collected from the 2-4 cm soil depth lyer. We used DTPA-TEA (ph 7.3) s the nutrient extrctor (Areu et l. 1998) to determine the Cu vilility in the soil. Lef smples were collected, s descried y Mttos Jr. et l. (217) nd Cu concentrtion in the dry mss ws determined ccording to Btgli et l. (1983) y plsm emission spectrometry (ICP-OES, Perkin-Elmer 51 PC, Norwlk, CT, USA). Fruit yield (kg/tree) ws evluted in ll 3 yers, y hrvesting fruits of the 1 centrl plnts of the experimentl plots. In the first nd third yers, fruit qulity ws ssessed y smpling five ornges per tree, in totl of 5 fruits.plot 1, to determine fresh weight, height nd width, juice cidity, solule solids (SS) ( Brix), SS/cidity rtio nd SS yield/4.8 kg ox, ccording to Redd et l. (1992). In Experiment 1, Cu concentrtion in the soil ws higher when pplied vi fertigtion s nitrte source in the first nd the third yers t the - 2 cm depth (Figure 1), s well s in the third yer t - 4 cm depth lyer (5.7 mg.dm 3 ) compred to the other tretments (4.1 mg.dm 3 ; p <.5; dt not shown). Regrdless of the fertiliser source, the ppliction of Cu vi fertigtion did not increse the micronutrient level in leves (Figure 1). Similrly, ppliction of Cu- vi fertigtion in sndy soil (ph 6.) in Florid ws not effective to increse the micronutrient levels in citrus leves ut ws efficient for iron, Mn nd Zn (Zekri nd Koo 1992). In this study, the sorption of Cu y roots ws not likely limited y interctions etween the micronutrient with the soil colloids due to the low K L vlue (.37 L.kg 1 ) estimted y the Lngmuir isotherm (Mout et l. 28; Hippler et l. 214), s well s the low content of orgnic mtter in the soil (23 g.dm 3 ). Furthermore, despite the high L vlue (73.2 mg.kg 1 ) for Cu in the soil of the present study, the ccumultion of this micronutrient due to frequent dditions cuses dsorption sites to ecome more sturted, which reduces the ffinity of the soil for the metl, in turn, incresing its concentrtion in solution nd, consequently, its vilility to the plnts (Mout et l. 28). However, when Cu is tken up y roots, nutrient prtitioning occurs minly into the root tissue, which ccounts for 6-8% of the totl micronutrient content in the plnt (Hippler et l. 216). A similr pttern is oserved for other micronutrients, such s Zn (Hippler et l. 215) ut not oron (Boretto et l. 23). In Experiment 2, the Cu concentrtion incresed up to 7. mg.dm 3 in the soil ( - 2 cm depth lyer) when pplied s sulfte, vi folir sprys, in the second nd third yers of evlution (Figure 2). However, no differences were verified in the Cu concentrtions in soil t the 2-4 cm depth lyer ( mg.dm 3 Cu) in the first nd third yers (dt not shown). Fruit yield (kg tree 1 ) Lef Cu (mg kg 1 ) Soil Cu (mg dm 3 ) Yer 1 Yer 2 Yer 3 Control Nitrte Sufte Figure 1. Concentrtion of copper (Cu) in the soil ( 2 cm lyer) nd in leves, nd fruit yield of sweet ornge trees fter ppliction of different fertiliser sources of Cu vi fertigtion. Wiskers on the rs show the stndrd error of mens. For the sme yer, different letters indicte significnt differences etween tretments ccording to Tukey s test (α =.5). Brgnti, Cmpins, v. 77, n. 2, p ,

4 F.W.R. Hippler et l. Although Cu is not tightly ound to soil, this metl showed no significnt concentrtion chnge in the 2-4 cm lyer, s lso oserved for oron (Mttos Jr. et l. 217). Furthermore, the Cu levels in leves incresed fter ppliction of Cu-nitrte in the first nd second yers (Figure 2). Although Cu-nitrte nd -sulfte fertiliser sources re highly wter-solule, the ccompnying ion influences the sorption of the metl y the lef surfce. For instnce, when pplied s the nitrte source, Cu sorption y leves ws higher compred to Fruit yield (kg tree 1 ) Lef Cu (mg kg 1 ) Soil Cu (mg dm 3 ) Control d Yer 1 c c c Yer 2 Yer 3 Nitrte Sulfte Figure 2. Concentrtion of copper (Cu) in the soil ( 2 cm lyer) nd in leves, nd fruit yield of sweet ornge trees fter ppliction of different fertiliser sources of Cu vi lef sprys. Wiskers on the rs show the stndrd error of mens. For the sme yer, different letters indicte significnt differences etween tretments ccording to Tukey s test (α =.5). the sulfte source, s lso verified for Zn nd Mn (Boretto et l. 23). Moreover, when pplied s the sulfte source, Cu might e esily wshed out from the cnopy y rinfll events nd rech the soil surfce (Fn et l. 211), s evident from the incresed Cu levels in the soil ( - 2 cm depth lyer; Figure 2). Appliction of Cu- incresed the micronutrient concentrtion in the citrus leves ut did not ffect soil concentrtion compred to the Control tretment (Figure 2). The folir ppliction of Cu s nitrte source, provided the highest micronutrient content in the leves in the first nd the second yer of evlutions (Figure 2), cusing plnt phytotoxicity tht ws verified y visul symptoms of lef injury (Figure 3). These symptoms were chrcterised y the presence of chlorotic leves tht were necrotic t the order s result of slt ccumultion (Figures 3,), which cused severe lef fll (Figures 3c,d). The deleterious effect of slt ccumultion nd consequent lef drop-off from trees tht received the Cu-nitrte s folir ppliction, reduced fruit yield y pproximtely 4% compred to the other tretments in the second yer of evlution (Figure 2). However, the toxicity symptoms were not oserved in the plnt growth of the following yer. Copper levels incresed in soil ( - 2 cm) nd leves in oth experiments in the third yer, compred to the second yer, when the phytosnitry mngement with copper-sed pesticides ppliction strted (p <.5; Figures 1 nd 2). Frequent sprying of copper-sed pesticides in citrus orchrds is required to control lef nd florl diseses, such s post-loom fruit drop, Alternri rown spot, lck spot nd citrus cnker (Silv Jr. et l. 216; Behlu et l. 217). However, copper-sed pesticides deliver Cu in n insolule form, such s copper hydroxide or oxychloride (Behlu et l. 217), which my hinder the metl uptke y plnts (Boretto et l. 23; Fvro et l. 217). Copper concentrtion in fruits ws quntified in the first yer, ut no differences were oserved in Experiment 1, with Cu sources pplied vi fertigtion (dt not shown). In contrst, in Experiment 2, the Cu levels in fruits incresed from 1.6 mg.kg -1 in Control plnts to 3.2 nd 3. mg kg -1 when folir ws spryed s sulfte nd, respectively, nd to 6.1 mg.kg -1 when pplied s nitrte (p <.5; dt not shown). Furthermore, the ppliction of Cu reduced the SS/cidity rtio (Rtio in Tle 1) of fruits in the first yer (Tle 1), regrdless of the fertiliser source or the ppliction method (fertigtion or folir), which is likely explined y the dely of fruit mturtion compred to the Control trees (Quggio et l. 26). The folir ppliction of Cu, s nitrte nd sulfte, in comprison to the Control plnts, reduced the fruit weight in the third yer ut incresed the 368 Brgnti, Cmpins, v. 77, n. 2, p , 218

5 Copper supply nd fruit yield of Citrus () () (c) (d) Figure 3. Visul symptoms of toxicity fter ppliction of copper nitrte in the second yer with lef urn () nd necrotic symptoms (), resulting in flling leves (c) nd (d). Tle 1. Fruit qulity of sweet ornges t the first nd third yer fter strt the ppliction of fertiliser sources of copper (Cu) vi fertigtion of folir spry. Appliction methods Cu Fertilisers Mss (g fruit-1) Height (cm) Width (cm) Juice (%) Acidity (g 1 ml-1) SS1 (ºBrix) Rtio SS/ox2 (kg) Yer 1 Control Fertigtion Nil Cu A3 1.8 Nitrte Sulfte Folir ppliction Nitrte B 1.7 Sulfte B B 1.8 Control Nil Cu 216 A B Nitrte Fertigtion Sulfte Yer 3 Folir ppliction Nitrte 28.9 B A Sulfte 29.2 B A AB AB 1. SS = Solule Solids; 2SS/ox yield of solule solids per ox (4.8 kg); 3Different lowercse letters in the sme yer re significntly different mong the Cu sources pplied vi fertigtion nd different uppercse letter in the sme yer re significntly different mong the Cu sources pplied vi folir (Tukey s test, p <.5). Brgnti, Cmpins, v. 77, n. 2, p ,

6 F.W.R. Hippler et l. SS/ox (Tle 1), in greement with the oservtions of Mttos Jr. et l. (217), wherey, smller fruits tended to exhiit higher SS concentrtion thn their lrger counterprts. Copper supply vi fertigtion is not effective to increse the levels of Cu in the leves of young citrus trees. Folir ppliction of nitrte nd sulfte sources of Cu re more efficcious to increse the folir levels of the nutrient thn Cu-. However, young trees with folir ppliction of solule sources re prone to exhiit symptoms of slt toxicity, which results in fruit yield losses. After inititing the phytosnitry mngement with frequent ppliction of copper-sed pesticides, there is no need to pply fertiliser sources contining Cu. ORCID IDS F. W. R. Hippler R. M. Boretto L. A. J. Teixeir J. A. Quggio D. Mttos-Jr REFERENCES Areu, C.A., Areu, M.F., Andrde, J.C. nd Rij, B. vn. (1998). Restrictions in the use of correltion coefficients in compring methods for the determintion of the micronutrients in soils. Communictions in Soil Science nd Plnt Anlysis 29, Allen, R. G., Pereir, L. S., Res, D. nd Smith, M. (1998). Crop evpotrnspirtion: guidelines for computing crop wter requirements. Irrigtion nd Dringe Pper 56. Food nd Agriculture Orgniztion of the United Ntions. Btgli, O.C., Furlni, A.M.C., Teixeir, J.P.F., Furlni, P.R. nd Gllo, J.R. (1983). Métodos de nálise químic de plnts. Cmpins: IAC. Boletim Técnico 78. Behlu, F., Scndeli, L.H.M., Silv Jr., G.J. nd Lnz, F.E. (217). Solule nd insolule copper formultions nd metllic copper rte of control cnker on sweet ornge trees. Crop Protection, 94, Boretto, A.E., Murok, T. nd Boretto, R.M. (23). Asorção e trnslocção de micronutrientes, plicdos vi folir, pelos citros. Lrnj, 24, Boretto, R.M., Quggio, J.A., Mttos Jr., D., Murok, T. nd Boretto, A.E. (211). Boron uptke nd distriution in field grown citrus trees. Journl of Plnt Nutrition, 34, Brdl, H. B. (24). Adsorption of hevy metl ions on soils nd soils constituents. Journl of Colloid nd Interfce Science, 277, Cmp, A.F. (1938). Symptomtology of deficiencies nd toxicities of citrus. Proceedings of the Florid Stte of Horticulturl Society, 51, Fn, J., He, Z., M, L.Q. nd Stoffell, P.J. (211). Accumultion nd vilility of copper in citrus grove soils s ffected y fungicide ppliction. Journl of Soils nd Sediments, 11, doi.org/1.17/s Fvro, M.A., Roeschlin, R.A., Rieiro, G.G., Mumry, R.L., Fernndez, L.N, Lutz, A., Sillon, M., Rist, L.M., Mrno, M.R. nd Griglio, N.F. (217). Reltionship etween copper content in ornge leves, cteril iofilm formtion nd citrus cnker disese control fter different copper tretments. Crop Protection, 92, Hippler, F.W.R., Reis, I.M.S., Boretto, R.M., Quggio, J.A. nd Mttos Jr., D. (214). Crcterístics dsortivs de solos e o suprimento de zinco e mngnês pr os citros. Citrus Reserch & Technology, 35, Hippler, F.W.R., Boretto, R.M., Quggio, J.A., Boretto, A.E., Areu Jr., C.H. nd Mttos Jr., D. (215). Uptke nd distriution of soil pplied zinc y Citrus trees - ddressing fertilisers use efficiency with 68 Zn leling. Plos One. journl.pone Hippler, F.W.R., Ciprino, D.O., Boretto, R.M., Quggio, J.A., Gziol, S.A., Azevedo, R.A. nd Mttos Jr., D. (216). Citrus rootstocks regulte the enzymtic nd nutritionl sttus nd ntioxidnt system of trees under copper stress. Environmentl nd Experimentl Botny, 13, Brgnti, Cmpins, v. 77, n. 2, p , 218

7 Copper supply nd fruit yield of Citrus Hippler, F.W.R., Boretto, R.M., Quggio, J.A. nd Mttos-Jr., D. (217). Copper in Citrus production: required ut voided. Citrus Reserch & Technology, 38, crt.icc67. Mttos Jr., D., Rmos, U.M., Quggio, J.A. nd Furlni, P.R. (21). Nitrogênio e core n produção de muds de citros em diferentes port-enxertos. Brgnti, 69, S Mttos Jr., D., Hippler, F.W.R., Boretto, R.M., Stuchi, E.S. nd Quggio, J.A. (217). Soil oron fertiliztion: the role of nutrient sources nd rootstocks in Citrus production. Journl of Integrtive Agriculture, 16, Mout, E.R., Sores, M.R. nd Csgrnde, J.C. (28). Copper dsorption s function of solution prmeters of vrile chrge soils. Journl of the Brzilin Chemicl Society, 19, dx.doi.org/1.159/s Quggio, J.A., Mttos Jr., D. nd Boretto, R.M. (21). Citros. In L. I. Prochnow, W. Csrin, S. R. Stipp (Eds.), Bos prátics pr o uso eficiente de fertilizntes. (v.3, p ). Pircic: Interntionl Plnt Nutrition Institute. Quggio, J.A., Mttos Jr., D. nd Cntrell, H. (26). Fruit yield nd qulity of sweet ornges ffected y nitrogen, phosphorus nd potssium fertiliztion in tropicl soils. Fruits, 61, dx.doi.org/1.159/s Redd, J.B., Hendrix, D.L. nd Hendrix Jr., C.M. (1992). Qulity control mnul for citrus processing plnts. v.1. Sfety Hrour: AGScience. Silv Jr., G.J., Scpin, M.S., Silv, F.P., Silv, A.R.P., Behlu, F. nd Rmos, H.H. (216). Spry volume nd fungicide rtes for citrus lck spot control sed on tree cnopy volume. Crop Protection, 85, Zekri, M. nd Koo, R.C.J (1992). Appliction of micronutrients to citrus trees through microirrigtion systems. Journl of Plnt Nutrition, 15, Brgnti, Cmpins, v. 77, n. 2, p ,