Polymeric derivatives of plant growth regulators: synthesis and properties

Abstract

The polymeric formulations of plant growth regulators (PGRs) are high molecular weight systems in which the PGR unit is attached to the polymeric chain by a hydrolysable chemical bond . These polymeric derivatives (esters, ethers, or else) of PGRs are characterised by the ability to release the active compound (PGR) from their solutions (mainly aqueous) in certain conditions . The release of the PGR can be controlled by external factors (pH, temperature, enzymes, solution concentration), and inherent properties of the whole macrosystem chemical structure, such as the type of the hydrolysable bond between PGR unit and the main polymeric chain, the structure of the polymer chain (e .g . molecular weight, level of hydrophilicity, and the content of hydrophobic groups, macromolecular conformation in solution etc .) . These controlled (slow) release PGRs display certain advantages over conventional PGR formulations due to their prolonged action, improved efficiency (e .g . wide range of effective concentrations) greater safety to non-target organisms and the applicators . In addition the ability of altering the solubility level and modifying the aplication form is of considerable interest . The biological activity efficiency of polymeric PGRs has been documented and the relation of this efficiency to the PGR unit hydrolytic release ability has been mentioned . Slow release polymeric PGRs are considered to solve certain problems in agriculture .Abbreviations : PGR = plant growth regulator ; C(S)RF = controlled (slow) release form ; PD = polymeric derivative ; ACC = 1-amino-cyclopropane-l-carboxylic acid ; NAA = 1-naphthylacetic acid ; 2,4-D = 2,4-dichlorophenoxyacetic acid ; IAA = indole-3-acetic acid ; BAP = N6-benzylaminopurine; ABA = abscisic acid; GA = gibberellin ; LMW = low molecular weight; HMW = high molecular weight . 69

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