No need for further fruit thinning in water-deprived loquat trees at preharvest

Abstract

Preharvest deficit irrigation (DI) during fruit growth may reduce fruit size in ‘Algerie’ loquat (Eriobotrya japonica Lindl.), but it can eventually enhance other parameters of fruit quality and earliness, making this crop more profitable. With the aim to determine the optimum level of fruit load per panicle under preharvest DI, we have compared harvest date, fruit size, yield, and revenue from ‘Algerie’ loquat trees analysing four different fruit loads under two irrigation treatments: T1, a control in which the trees’ water requirements were fully satisfied from bloom to harvest; and T2 (a treatment of preharvest DI) in which irrigation was withheld from stage II of fruit development until the end of harvest (a total of 13 and 14 weeks, depending on the season). The four levels of fruit load were 1, 2, 3 and 4 fruits per panicle. The results showed the absence of significant interactions between irrigation and fruit load treatments, probably due to the low levels of water stress reached during preharvest. DI did not enhance fruit maturity substantially and therefore failed to advance the harvest date. Pack out was slightly improved by heavier fruit thinning treatments; however, that improvement did not compensate the important yield loss caused by the reduction in the number of fruit per panicle. Therefore, a crop load of 4 fruits per panicle provided the highest revenue in both irrigation treatments. An average water saving of 2281m3/ha (33% of the water applied in T1) was achieved by preharvest DI. In conclusion, the low levels of water stress reached by withholding irrigation in spring in SE Spain do not impose heavier fruit thinning in ‘Algerie’ loquats.