In deciduous fruit species, floral bud initiation, differentiation and organogenesis take place during the summer–autumn season that precedes anthesis. Among factors able to modify the regularity of these processes, water availability represents a crucial aspect. This investigation aimed to assess the influence of different summer and autumn water deficit and re-watering treatments on floral morphogenesis, xylem vessel differentiation and quality of flower buds. Trials were carried out on two-year-old potted apricot trees (cv. ‘Portici’) which were submitted to different regimes: (i) fully irrigated plants; (ii) stressed plants in June (S1), July (S2) and October (S3) followed to re-watering. Midday stem water potential was used to determine water status, and leaf gas exchanges were measured during trials. Histological analyses on floral differentiation, xylem progression within flower buds and biological observations were carried out. Both summer water stress periods affected the floral differentiation leading to a temporary shutdown. The S1 trees were able to recover the development of meristematic apices while S2 had a strong delay. All drought treatments caused a slower xylem progression, variations in bud size, blooming entity and flower anomalies. Results particularly highlights the importance of water availability also in early autumn.

中文翻译：

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夏，秋季缺水对杏花期分化和花芽生长的影响

在落叶果树种中，花芽的萌芽，分化和器官发生发生在花前的夏秋季。在能够改变这些过程的规律性的因素中，水的可用性是至关重要的方面。这项研究旨在评估不同的夏，秋季缺水和复水处理对花卉形态发生，木质部血管分化和花蕾质量的影响。试验是对两岁的杏树盆栽（“ Portici”）进行的，这些杏树分别接受了不同的处理方式：（i）完全灌溉的植物；（ii）在6月（S1），7月（S2）和10月（S3）的受压植物随后重新浇水。使用午间茎水势来确定水的状况，并在试验过程中测量叶片的气体交换。对花芽分化，花芽内木质部的进程和生物学观察进行了组织学分析。两个夏季的水分胁迫期都影响了花的分化，导致暂时关闭。S1树木能够恢复分生性尖顶的发育，而S2则具有很强的延迟性。所有干旱处理均导致木质部进程变慢，芽大小变化，实体开花和花异常。结果尤其突出了在初秋时节供水的重要性。所有干旱处理均导致木质部进程变慢，芽大小变化，实体开花和花异常。结果尤其突出了在初秋时节供水的重要性。所有干旱处理都导致木质部进程变慢，芽大小变化，实体开花和花异常。结果尤其突出了在初秋时节供水的重要性。