Effects of foliar application of organic acids on strawberry plants

9 Pags.- 5 Figs.- 4 Tabls.- 1 Suppl. Data (Multimedia component). © The Authors. Published by Elsevier Masson SAS. This is an open access article under the CC BY-NC-ND license.The large economic costs and environmental impacts of iron-chelate treatments has led to the search for alternative methods and compounds to control iron (Fe) deficiency chlorosis. Strawberry plants (Fragaria x ananassa) were grown in Hoagland's nutrient solution in a greenhouse with two levels of Fe: 0 and 10 μM Fe(III)-EDDHA. After 20 days, plants growing without Fe showed typical symptoms of Fe deficiency chlorosis in young leaves. Then, the adaxial and abaxial sides of one mature or one young leaf in each plant were brushed with 10 mM malic (MA), citric (CA) or succinic (SA) acids. Eight applications were done over a two-week period. At the end of the experiment, the newly emerged (therefore untreated), young and mature leaves were sampled for nutritional and metabolomic analysis, to assess the effectiveness of treatments. Leaf regreening was monitored using a SPAD-502 apparatus, and the activity of the ferric chelate-reductase activity (FCR) was measured using root tips. Iron deficiency negatively affected biomass and leaf chlorophyll but did not increase FCR activity. Application of succinic acid alleviated the decrease in chlorophyll observed in other treatments, and the overall nutritional balance in the plant was also changed. The concentrations of two quinic acid derivatives increased under Fe deficiency and decreased in plants treated with succinic acid, and thus they are proposed as Fe stress markers. Data suggest that foliage treatments with carboxylates may be, in some cases, environmentally friendly alternatives to Fe(III)-chelates. The importance of Fe mobilization pathways in the formulation of new fertilizers is also discussed.This study was funded by the National Projects (UID/Multi/04326/2019 and UIDB/04326/2020, UIDP/04326/2020 and LA/P/0101/2020) from Foundation for Science and Technology (FCT) and from the operational programme CRESC Algarve 2020 and COMPETE 2020 through project EMBRC. PT and ALG-01-0145-FEDER-022121. JA was partially supported by the Spanish Research Agency (Grant PID2020–115856RB-100 funded by MCIN/AEI/10.13039/501100011033). T.S. and J.P.S. are thankful to FCT for the Grants SFRH/BD/144764/2019 and REEQ/717/QUI/2005 respectively.Peer reviewe