Levels of extractable para-coumaric acid in the exo-mesocarp and seed of persisting and abscising peach fruit

Researches were carried out with 12 year-old "Andross" peach trees, following the same procedure in monitoring fruit growth as previously described (Ramina and Masia, 1980). Three subpopulations of fruits with different abscission potential were discriminated during stage I. Transverse fruit diameter and abscission were monitored at 6-7 day intervals during the entire period of fruit development. Fruit abscission was expressed as percent of the original number of flowers. Three samples of fruit from each subpopulation were collected at about weekly intervals throughout stages I, II and III of growth, and separated into exo-mesocarp and seed. Procedures used for extraction and purification were those previously described (Ramina and Masia, 1980). The nature of the inhibitor was established by combined gas chromatography-mass spectrometry. Its level was determined spectrophotometrically and confirmed by wheat coleoptile and cress seed assay.