THE INDUSTRIAL USE OF GIBBERELLIC ACID AND ITS SCIENTIFIC BASIS-A REVIEW

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Abstract
Over the last 15 years numerous studies, both fundamental and applied, have ensured for gibberellic acid (GA3) a firm place in the routine commercial malting of barley and the production of fruits. A large number of the thirty‐eight gibberellins so far characterized occur naturally, e.g. gibberellic acid in germinating barley. Commercial application of gibberellic acid during malting therefore supplements the natural endogenous levels of this hormone. Small additions of gibberellic acid accelerate the production and release into the endosperm of enzymes which degrade the hemicellulosic‐protein‐starch complex into essential brewing materials such as sugar, peptides and amino acids. A combination of abrasion with gibberellic acid application results in further acceleration of the malting process. Abrasion of the pericarp at the distal end of barley grains allows them, in the presence of normal levels of gibberellic acid, to malt simultaneously from both their embryo and non‐embryo ends: malting time is drastically reduced and soluble malt extract is increased. In spite of the widespread industrial use of gibberellic acid, the cellular mechanisms through which gibberellic acid elicits its various actions on plant growth and development are not yet known; however, with barley aleurone cells gibberellic acid can induce drastic reorganization and synthesis of subcellular organelles. The net result of gibberellin treatment may be vigorous production and secretion of hydrolytic enzymes or, in other circumstances a rapid acceleration of growth and development. It is as yet unknown whether these apparently diverse expressions of gibberellin action have a similar biochemical basis.