Controlled crosses of 'Sunki' with Poncirus trifoliata and its hybrids were performed in order to estimate the zygotic seedlings frequency, by comparing its vigour with the ones from nucellar origin. A relatively high fruit set rate of 40% was achieved, which indicates a good compatibility within the parental crosses. The observed frequency of zygotic seedlings was 48% and certainly this was underestimated due to the presence of Poncirus hybrids in the pollinations. Epicotyl length and the true leaf number character estimates showed that 91% of the identified hybrids may be similar or even superior to the nucellar ones in relation to plant vigour.
