Hybrid vigour on 'Sunki' mandarin

Controlled crosses of 'Sunki' with Poncirus trifoliata and its hybrids were performed in order to estimate the zygotic seedlings frequency, by compari ng its vigour with the ones from nucellar origin. A relatively high fruit s et rate of 40% was achieved, which indicates a good compatibility within th e 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 est imates showed that 91% of the identified hybrids may be similar or even sup erior to the nucellar ones in relation to plant vigour.