(3S,3aR,4S,4aS,7S,9aR,9bR,12S)-7,12-dihydroxy-3-methyl-6-methylene-2-oxoperhydro-4a,7-methano-9b,3-propeno[1,2-b]furan-4-carboxylic acid

(1a,2b,4aa,4bb,10b)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1,10-dicarboxylic acid 1,4a-lactone 

C₁₉H₂₂O₆

Crystalline solid.

223-225 ℃(decomp.)

In water 5 g/l (room temperature). Soluble in methanol, ethanol, acetone, and aqueous alkalis; slightly soluble in diethyl ether and ethyl acetate. Insoluble in chloroform. Potassium, sodium, and ammonium salts: Readily soluble in water (potassium salt 50 g/l)

Dry gibberellic acid is stable at room temperature, but slowly undergoes hydrolysis in aqueous or aqueous-alcoholic solutions, DT₅₀ (20 ℃) c. 14 d (pH 3-4), 14 d (pH 7). In alkalis, undergoes a rearrangement to less biologically-active compounds. Decomposed by heat.

4.0

Acts as a plant growth regulator on account of its physiological and morphological effects in extremely low concentrations. Translocated. Generally affects only the plant parts above the soil surface.

Has a variety of applications, e.g. to improve fruit setting of clementines and pears (especially William pears); to loosen and elongate clusters and increase berry size in grapes; to control fruit maturity by delaying development of the yellow colour in lemons; to reduce rind stain and retard rind ageing in navel oranges; to counteract the effects of cherry yellows virus diseases in sour cherries; to produce uniform seedling growth in rice; to promote elongation of winter celery crop; to induce uniform bolting and increase seed production in lettuce for seed; to break dormancy and stimulate sprouting in seed potatoes; to extend the picking season by hastening maturity in artichokes; to increase the yield in forced rhubarb; to increase the malting quality of barley; to produce brighter-coloured, firmer fruit, and to increase the size of sweet cherries; to increase yields and aid harvesting of hops; to reduce internal browning and increase yields of Italian prunes; to increase fruit set and yields of tangelos and tangerines; to improve fruit setting in blueberries; to advance flowering and increase the yield of strawberries; and also a variety of applications on ornamentals. Application rates up to 80 g/a per application, depending on desired effect.

Incompatible with alkaline materials and solutions containing chlorine.

Acute oral LD₅₀ for rats and mice >15 000 mg/kg.

Acute percutaneous LD₅₀ for rats >2000 mg/kg. Non-irritating to skin and eyes.

No ill-effect on rats subjected to 400 mg/l for 2 h/d for 21 d.

(90 d) for rats and dogs >1000 mg/kg diet (6 d/w).

WHO (a.i.) U; EPA (formulation) III

Acute oral LD₅₀ for bobwhite quail >2250 mg/kg. Acute oral LC₅₀ >4640 mg/kg.

LC₅₀ (96 h) for rainbow trout >150 ppm.

Product analysis by hplc; details available from Syngenta. Residues determined by tlc (V. W. Winkler, Anal. Methods Pestic. Plant Growth Regul., 1978, 10, 545).