PREFLOWERING AND PREHARVEST DEFICIT IRRIGATION EFFECTS ON LOQUAT PHENOLOGY
Previous results have shown that preflowering deficit irrigation (DI) imposed shortly after prior years harvest promotes a consistent advancement in next season flowering and harvest dates of Algerie loquat (Eriobotrya japonica Lindl.). Regardless of the potential negative effects on fruit size, an additional period of DI during the phase of rapid fruit growth may enhance ripening and cause therefore a further advancement in harvest and a higher profitability of this crop. In order to determine and to separate the effects of two distinct DI periods on loquat phenology, we have applied during three consecutive seasons three irrigation treatments, C: control trees without watering restrictions; T1 (preflowering DI): trees with no irrigation during a period of 6/8 weeks from the beginning of June to mid-July, and T2 (preharvest DI): trees with no irrigation during preflowering plus an additional period of no watering from stage II of fruit development to harvest (9 weeks more, from mid-February to April). On these trees, we monitored reproductive phenology and success (fruit and seed set), and calculated the changes in heat units requirements due to the modification of loquat phenology by estimating growing degree days (GDD) accumulated by the trees between full bloom to harvest. The results showed that preflowering DI advances loquat full bloom between 12 and 27 days depending on the season. Full bloom period was also shorter in T1 and T2 in comparison to C. Earlier blooming lead to earlier harvest (T1 and T2 reached harvest between 8-20 days before, depending on the season and treatment) and to obtaining higher percentages of precocious yield (between 22 and 47% more), without consistent negative effects on fruit size. DI advanced blooming but increased GDD requirements in T1 and T2 trees. The reproductive success was not modified due to the changes in loquat phenology and natural fruit set and seed number was the same in all treatments. Our experi¬ments confirm that preflowering DI modifies loquat phenology enhancing fruit earli¬ness and crop profitability. The results also show that the additional DI period during preharvest did not cause any substantial advancement in harvest dates, but caused substantial saving in irrigation water.
Stellfeldt, A., Hueso, J.J. and Cuevas, J. (2014). PREFLOWERING AND PREHARVEST DEFICIT IRRIGATION EFFECTS ON LOQUAT PHENOLOGY. Acta Hortic. 1038, 639-645
blooming date, harvest date, growing degree days