Abstract: The sugar content of plants is increased by a method in which the plants are treated, from 1 to 15 weeks prior to harvesting, with a compound of the formula (I) ##STR1## where R.sup.1 is alkyl of 1 to 4 carbon atoms, R.sup.2 is alkyl of 1 to 4 carbon atoms, unsubstituted or halogen-substituted alkenyl of 3 to 5 carbon atoms or alkynyl of not more than 5 carbon atoms, R.sup.3 is a non-aromatic heterocyclic structure which has 5 to 7 ring members and no double bonds or one double bond in a heterocyclic ring, contains 1 or 2 hetero atoms from the group consisting of sulfur and oxygen, and can be substituted by alkyl of not more than 3 carbon atoms, and X is H or C00-alkyl, or one of its plant-tolerated salts.

Abstract: A process for regulating plant growth, wherein the plants, the seed or the soil are treated with a polycyclic nitrogen-containing compound of the formula ##STR1## R.sup.2 is --N.dbd.N-- or --NH--NH, and R.sup.3 is ##STR2## or phenyl which is substituted by halogen, fluoroalkyl of 1 to 2 carbon atoms, NO.sub.2 or C.sub.1 -C.sub.3 -alkyl, the equivalent of less than 100 g of active ingredient being employed per hectare.

Abstract: New agents for regulating plant growth, especially for reducing the height of plants, containing a mixture of a quaternary substituted thianium or ammonium salt and a phosphonic acid derivative.

Abstract: Agents for regulating plant growth, especially for improving abscission, which contain substituted ammonium salts or substituted fatty acid amides, and a process for improving abscission with these agents.