Physiological Response of New Citrus Rootstocks under the Effect of Lime Induced Iron Chlorosis Stress Conditions

Citrus orchards are highly affected by iron chlorosis in Mediterranean Basin, which is the second-highest producing region worldwide. In addition, citrus orchards from the Mediterranean Basin are exposed to emerging diseases, such as Huanglongbing, the most devastating citrus disease worldwide. Consequently, citrus rootstock can serve as an interesting tool to reduce crop losses caused by these abiotic and biotic stresses. In our study, we evaluated the effect of four Fe-chlorosis stress treatments on six new citrus rootstocks under greenhouse conditions and compared with Carrizo citrange and Forner-Alcaide 5. Above-ground symptoms and chlorophyll index (SPAD) were recorded on a regular basis during the experiment. At the end of the assay, root, stem, and leaves biomass and Fe concentration in leaves were recorded. Plant symptoms were detected under Fe-chlorosis stress treatments, in which 2247 x 6070-02-2 and UFR-6 displayed lower incidence than other citrus rootstocks. These plant symptoms were in keeping with the SPAD response per citrus rootstock. Almost all citrus rootstock reported the highest biomass reduction under the treatment of 1 g CaCO3/l pH 9. Only two citrus rootstocks (Carrizo citrange and B11R5T49) achieved the highest Fe concentration on leaves under control conditions compared with the other treatments per citrus rootstock.