Two-year-old potted peach 'Zaojiubao' (Prunus persica L. Batsch) trees on wild P. persica rootstock were subjected either to regulated deficit irrigation (RDI), in which trees were water stressed during fruit pit hardening (stage II) followed by rewatering during the final rapid fruit growth stage (stage III), or to half-root stress (HRS) treatments during the same two stages. To investigate the allocation of carbon assimilates among sink organs, shoots were fed with (CO2)-C-14 twice, either during stage II or stage III The distribution coefficient (K) represented the competitive sink strength. RDI and HRS induced an altered allocation pattern of C-14-assimilates. The import to shoot apexes was reduced. However, there were no significant reduction in fruit diameter and weight. Moreover, the Ks of the fruit subparts of RDI and HRS treated trees were similar to or sometimes higher than those of CK trees. There were more C-14-assimilates and higher K values of seeds from RDI trees during stage III compared with CK In addition, stressed roots seemed to have stronger abilities to attract C-14-assimilates. It is concluded that RDI and HRS resulted in a decreased sink activity in the shoot and a change of carbon allocation toward stressed roots and seeds without negative effects on fruit growth. (C) 2009 Elsevier Ireland Ltd. All rights reserved