Three short phloem sections - above, at and below the graft union - of apricot cultivars on three different Prunus species were analyzed for the content of flavan-3-ols by HPLC. The flavanol pattern changed depending on the graft combination. There was a scion effect on the rootstock flavanols in some cases, and reversely, the rootstocks sometimes influenced the scions. With respect to the three phloem sections along the union a proportional decrease from the scion to the rootstock could sometimes be observed. An excessive accumulation of flavanols Nr. 2, 6 ((+)-catechin) and 16 ((-)-epicatechin) just in the middle union section was often a characteristic feature. The cv. 'Moniqui' on 'Marianna 2624' considered to be a less compatible combination showed two characteristic trends: (a) higher levels of flavanols as compared to the 'Luizet' graftings and (b) an accumulation of the already mentioned flavanols Nr. 2, 6 and 16 in the union section.
