Excessive rough and thick peel, linked with large fruit sizes is found in ‘Shamouti’ oranges (Citrus sinensis (L.) Osbeck) grown under marginal soil and climatic conditions. This condition was overcome by early (April-May) sprays of succinic acid-2,2-dimethylhydrazide (SADH) and 2-chloroethyltrimethylammonium chloride (CCC, chlormequat), probably counteracting high endogenous promotors found in rough tissues. While SADH is too expensive to be profitable and it usually decreases fruit size, CCC can be used without this effect and is commercially rewarding.
Band application of MgCl2·6H2O under the tree canopy of ‘Shamouti’ orange [Citrus sinensis (L.) Osbeck] trees significantly increased leaf Mg and Cl concentration. MgSO4 and MgO were not effective. Fertigation with MgCl2·6H2O was less efficient than band application and was not superior to foliar application of Mg(NO3)2·6H2O for increasing leaf Mg concentrations. In spite of high Cl concentration of the leaves, no visible toxicity symptoms were observed.