Abstract: Compounds corresponding to the general formula: ##STR1## in which R represents hydrogen, an alkyl radical, a halogenated alkyl radical, a cycloalkyl radical, an optionally substituted aryl radical, an optionally substituted aralkyl radical, an acyl radical, aroyl radical or an optionally substituted heterocycle;R.sub.3 represents hydrogen, aralkyl radical containing 1 to 5 carbon atoms;R.sub.2 represents hydrogen, an alkyl radical (optionally halogenated or substituted by a hydroxyl), a formyl radical, an acyl radical, a carbamoyl radical monosubstituted or disubstituted on the nitrogen;R and R.sub.2 cannot both represent hydrogen;X represents oxygen or sulphur, and their salts, especially their sulphonium salts. Such compounds are useful for modifying the growth of plants.

Abstract: Plant-protection compositions. They contain as active material at least one ixed chelate with two coordinates, such as ethylene diamine, triethanolamine, tartaric acid, picolic acid, dipicolic acid, dihydro-2,4-benzoic acid, salicylic acid, p-aminosalicylic acid, 5-sulphosalicylic acid, 8-hydroxyquinoline, sodium pyrocatechol-3,5-disulphonate, ethylene diamine diacetic acid (or its alkali salts), ethylene diamine tetraacetic acid (or its alkali salts), nitrilotriacetic acid, sodium dihydroxynaphthalene disulphonate. These compositions protect plants against hypoferric chlorosis.