Nutritional status and productivity of Anna apple trees in the year following autumn irrigation determent

This study was conducted over two successive seasons in 2018/2019 and 2019/2020 on 6-year-old Anna apple trees to determine the effects of autumn irrigation determent on fruit phenological development stages, flowering density, initial fruit set, fruit yield, fruit characteristics, and nutritional status. There were five irrigation treatments: T1, control (no determent); T2, irrigation determent for 30 d from October 1st to October 30th; T3, irrigation determent for 45 d from October 1st to November 14th; T4, irrigation determent for 30 d from October 10th to November 9th; and T5, irrigation determent for 45 d from October 10th to November 24th. The results revealed that in both seasons, the dates for earliest and latest bud burst, petal fall, and fruit set were in T1 and T5. Moreover, in both seasons, T3 significantly improved the number of opened flowers for 100 spur bud inflorescences, percentage of fruiting spurs, initial fruit set, fruit yield, yield increment, fruit firmness, total soluble solids (TSS), total and reducing sugars, and anthocyanin content. Meanwhile, the percentage of vegetative spurs, fruit weight, volume, length, diameter, leaf chlorophyll content, and leaf mineral content (N, P, K, Ca, and Mg) were higher in the control treatment in both seasons. Thus, irrigation determent during autumn for 45 d from October 1st to November 14th (T3) was the most conclusion efficient treatment for Anna apple productivity and the non-critical periods for apple agricultural practices.