Deficit Irrigation in 'Golden Nugget' Loquat

Loquat (Eriobotrya japonica Lindl.) blooms in autumn, develops its fruit during winter and ripens them in early spring. This unusual reproductive cycle makes fruit earliness paramount in this crop, and any cultural technique able to improve fruit earliness results extremely important to loquat growers. In this regard, deficit irrigation (DI) in 'Algerie' loquat, starting in June and finishing before August, advances next season bloom and harvest, increasing crop profitability. Highly successful experiments have been carried out in the past on this topic in 'Algerie' loquat trees grafted on quince, but DI strategies need to be adjusted for different cultivar-rootstock combinations. In order to investigate whether prebloom DI generates similar outcomes in vigorous cultivars, we studied the response of 'Golden Nugget' grafted on 'BA-29' quince to prebloom DI during two consecutive seasons (2010/11 and 2011/12) in an orchard located in El Ejido, Almeria, Spain. The results show that withholding irrigation for 7-9 weeks significantly reduced stem water potential reaching at the end of the DI period a minimum record of -2,0 MPa. This severe water stress allowed an advancement of full bloom of between 9 and 12 days, depending on the season, in water-deprived trees with respect to fully-irrigated trees. Unfortunately, this advancement was almost unnoticed at harvest date. Nonetheless, no negative effects were produced by adopting DI and important water savings and increases in water use efficiency were achieved with this irrigation strategy.