[Changes in abscisic acid content during fruit development in Solanum lycopersicum L].

The presence of abscisic acid (ABA) in methanol extracts from tomato fruits was determined by thinlayer chromatography, UV absorption, optical rotatory dispersion (ORD) and biological activity in different bioassays. In two growth periods (1968 and 1969), quantitative changes of the ABA content in growing fruits of the variety "Moneymaker" were measured by Milborrow's "racemate dilution technique". The absolute content of ABA (μg/l fruit) was increased during fruit development, reached a maximum, and then decreased in ripening fruits. The ABA concentration (μg/kg) was also highest in unripe fruits and decreased during ripening. Similar results were obtained with the same variety and with the variety "Haubners Vollendung" by means of ORD and UV measurement only, without application of Milborrow's technique.