BACKGROUND: Glyphosate is used to control weeds in citrus orchards, and accidental spraying or wind drift onto the seedlings may cause growth arrest owing to metabolism disturbance. Two experiments were carried out to investigate the effect of non-lethal rates (0, 180, 360 and 720 g AI ha-1) of glyphosate on four-month-old 'Cravo' lime, Citrus limonia (L.) Osbeck, seedlings. Photosynthesis and the concentrations of shikimic acid, total free amino acids and phenolic acids were evaluated. RESULTS: Only transitory effects were observed in the contents of shikimate and total free amino acids. No visual effects were observed. CONCLUSION: The present study showed that glyphosate at non-lethal rates, which is very usual when accidental spraying or wind drift occurs in citrus orchard, did not cause severemetabolic damage in 'Cravo' lime seedlings. © 2009 Society of Chemical Industry.654420425Franz, J.E., Mao, M.K., Sikorski, J.A., Glyphosate: a Unique Global Herbicide (1997) ACS Monograph No. 189, p. 653. , American Chemical Society, Washington, DCWang, C.Y., Effect of glyphosate on aromatic amino acid metabolism in purple nutsedge . Cyperus rotundus) (2001) Weed Technol, 15, pp. 628-635Shieh, W.-J., Geiger, D.R., Servaites, J.C., Effect of N-(phosphonomethyl)glycine on carbon assimilation and metabolism during a simulated natural day (1991) Plant Physiology, 97 (3), pp. 1109-1114Devine, M.D., Duke, S.O., Fedtke, C., (1993) Physiology of Herbicide Action, p. 441. , Prentice Hall, Englewood Cliffs, NJEker, S., Ozturk, L., Yazici, A., Erenoglu, B., Romheld, V., Cakmak, I., Foliar-applied glyphosate substantially reduced uptake and transport of iron and manganese in sunflower (Helianthus annuus L.) plants (2006) Journal of Agricultural and Food Chemistry, 54 (26), pp. 10019-10025. , DOI 10.1021/jf0625196Buehring, N.W., Massey, J.H., Reynolds, D.B., Shikimicacidaccumulation in field-grown corn . Zeamays) following simulated glyphosate drift (2007) J Agric Food Chem, 55, pp. 819-824Koger, C.H., Shaner, D.L., Krutz, L.J., Walker, T.W., Buehring, N., Henry, W.B., Thomas, W.E., Wilcut, J.W., Rice (Oryza sativa) response to drift rates of glyphosate (2005) Pest Management Science, 61 (12), pp. 1161-1167. , DOI 10.1002/ps.1113Bellaloui, N., Reddy, K.N., Zablotowicz, R.M., Mengistu, A., Simulated glyphosate drift influences nitrate assimilation and nitrogen fixation in non-glyphosate-resistant soybean (2006) Journal of Agricultural and Food Chemistry, 54 (9), pp. 3357-3364. , DOI 10.1021/jf053198lDuke, S.O., Rimando, A.M., Pace, P.F., Reddy, K.N., Smeda, R.J., Isoflavone, glyphosate, and aminomethylphosphonic acid levels in seeds of glyphosate-treated, glyphosate-resistant soybean (2003) J Agric Food Chem, 51, pp. 340-344Fuchs, M.A., Geiger, D.R., Reynolds, T.L., Bourque, J.E., Mechanisms of glyphosate toxicity in velvetleaf (Abutilon theophrasti medikus) (2002) Pesticide Biochemistry and Physiology, 74 (1), pp. 27-39. , DOI 10.1016/S0048-3575(02)00118-9, PII S0048357502001189Baerson, S.R., Rodriguez, D.J., Biest, N.A., Tran, M., You, J., Kreuger, R.W., Dill, G.M., Gruys, K.J., Investigating the mechanism of glyphosate resistance in rigid ryegrass (Lolium ridigum) (2002) Weed Science, 50 (6), pp. 721-730. , DOI 10.1614/0043-1745(2002)050[0721:ITMOGR]2.0.CO;2Rodrigues, B.N., Almeida, F.S., (2005) Guia de Herbicidas, p. 592. , 5th edition. IAPAR, Londrina, BrazilErickson, C.G., Management of glyphosate-related citrus fruit drop (1996) Proc Fla State Hort Soc, 109, pp. 40-42Neumann, G., Kohls, S., Landsberg, E., Stock-Oliveira Souza, K., Yamada, T., Romheld, V., Relevance of glyphosate transfer to non-target plants via the rhizosphere (2006) Journal of Plant Diseases and Proctectio, Supplement, (20), pp. 963-969Tucker, D.P.H., Glyphosate injury symptom expression in citrus (1977) HortScience, 12, pp. 498-500Hoagland, D., Arnon, D.I., (1950) The Water-Culture Method for Growing Plants without Soil, pp. 1-32. , University of California, Berkeley, CA, California Agricultural Experiment Station 347Singh, B.K., Shaner, D.L., Rapid determination of glyphosate injury to plants and identification of glyphosate-resistant plants (1998) Weed Technology, 12 (3), pp. 527-530Yemm, E.M., Cooking, E.C., Estimation of aminoacids by ninhydrin (1955) Analyst, 80, pp. 209-213Swain, T., Hills, W.E., The phenolic constituents of. Prunus domestica. I. The quantitative analysis of phenolic constituents (1959) J Sci Food Agric, 10, pp. 63-68Bolh'ar-Nordenkampf, H.R., Öquist, G., Chlorophyll fluorescence as a tool in photosynthesis research (1993) Photosynthesis and Production in a Changing Environment: A Field and Laboratory Manual, pp. 193-206. , ed. by Hall DO, Scurlock JMO, Bolhar-Nordenkampf HR, Leegood RC and Long SP. Chapman and Hall, London, UKPline, W.A., Wilcut, J.W., Duke, S.O., Edmisten, K.L., Wells, R., Tolerance and accumulation of shikimic acid in response to glyphosate applications in glyphosate-resistant and nonglyphosate-resistant cotton (Gossypium hirsutum L.) (2002) Journal of Agricultural and Food Chemistry, 50 (3), pp. 506-512. , DOI 10.1021/jf0110699Taylor Jr, G.E., Tingey, D.T., Gunderson, C.A., Photosynthesis, carbon allocation, and growth of sulfur dioxide ecotypes of Geranium carolinianum L. (1986) Oecologia, 68 (3), pp. 350-357Becerril, J.M., Duke, S.O., Lydon, J., Glyphosate effects on shikimate pathway products in leaves and flowers of velvetleaf . Abutilon theophrasti Medic.) (1989) Phytochemistry, 28, pp. 695-699Duke, S.O., Hoagland, R.E., Effect of glyphosate on the metabolism of phenolic compounds: VII. Root-fed aminoacids and glyphosate toxicity in soybean . Glycine max) seedlings (1981) Weed Sci, 29, pp. 297-302Afek, U., Sztejnberg, A., Effects of fosetyl-Al and phosphorous acid on scoparone, a phytoalexin associated with resistance of citrus to. Phytophthora citrophthora (1989) Phytopathology, 79, pp. 736-739Arimoto, Y., Homma, Y., Ohsawa, T., Studies on citrus melanose and citrus stem-end rot by. Diaporthe citri (Faw.) Wolf. Part 5. Identification of phytoalexin in melanose spot (1986) Ann Phytopathol Soc Japan, 52, pp. 620-625Kim, J.J., Ben-Yehoshua, S., Shapiro, B., Henis, Y., Carmeli, S., Accumulation of scoparone in heat-treated lemon fruit inoculated with Penicillium digitatum Sacc. (1991) Plant Physiology, 97 (3), pp. 880-885Duke, S.O., Wedge, D.E., Cerdeira, A.L., Matallo, M.B., Interactions of synthetic herbicides with plant disease and microbial herbicides (2007) Novel Biotechnologies for Biocontrol Agent Enhancement and Management, pp. 277-296. , by Vurro M and Gressel J. Springer, Amsterdam, The Netherlands