Yang Weiwei, Pallas Benoît, Durand Jean-Baptiste, Martinez Sébastien, Han Mingyu, Costes Evelyne
INRA, UMR AGAP, Equipe Architecture et Fonctionnement des Espèces Fruitières, Avenue d'Agropolis - TA-A-108/03, 34398 Montpellier Cedex 5, France.
College of Horticulture, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi 712100, China.
Tree Physiol. 2016 Nov;36(11):1369-1381. doi: 10.1093/treephys/tpw068. Epub 2016 Sep 1.
Water stress (WS) generates a number of physiological and morphological responses in plants that depend on the intensity and duration of stress as well as the plant species and development stage. In perennial plants, WS may affect plant development through cumulative effects that modify plant functions, architecture and production over time. Plant architecture depends on the fate of the terminal and axillary buds that can give rise, in the particular case of apple, to reproductive or vegetative growth units (GUs) of different lengths. In this study, the impact of long-term WS (7 years) on the fate of terminal and axillary buds was investigated in relation to flowering occurrence and production pattern (biennial vs regular) in the 'Granny Smith' cultivar. It was observed that WS decreased the total number of GUs per branch, regardless of their type. Conversely, WS did not modify the timing of the two successive developmental phases characterized by the production of long and medium GUs and an alternation of floral GUs over time, respectively. The analysis of GU successions over time using a variable-order Markov chain that included both the effects of the predecessor and water treatment revealed that WS reduced the transition towards long and medium GUs and increased the transition toward floral, short and dead GUs. WS also slightly increased the proportion of axillary floral GUs. The higher relative frequency of floral GUs compared with vegetative ones reduced the tendency to biennial bearing under WS. The accelerated ontogenetic trend observed under WS suggests lower vegetative growth that could, in turn, be beneficial to floral induction and fruit set.
水分胁迫（WS）会在植物中引发一系列生理和形态反应，这些反应取决于胁迫的强度和持续时间以及植物种类和发育阶段。在多年生植物中，水分胁迫可能通过累积效应影响植物发育，这些效应会随着时间改变植物的功能、结构和产量。植物结构取决于顶芽和腋芽的命运，在苹果这种特殊情况下，顶芽和腋芽可产生不同长度的生殖或营养生长单元（GUs）。在本研究中，针对‘澳洲青苹’品种，研究了长期水分胁迫（7年）对顶芽和腋芽命运的影响，以及与开花发生和结果模式（隔年结果与正常结果）的关系。观察到，无论生长单元类型如何，水分胁迫都会减少每个枝条上生长单元的总数。相反，水分胁迫并未改变两个连续发育阶段的时间，这两个阶段分别以产生长生长单元和中生长单元以及随着时间推移花生长单元交替出现为特征。使用包含前一个生长单元和水分处理效应的可变阶马尔可夫链对生长单元随时间的序列进行分析，结果表明，水分胁迫减少了向长生长单元和中生长单元的转变，并增加了向花生长单元、短生长单元和死亡生长单元的转变。水分胁迫还略微增加了腋花生长单元的比例。与营养生长单元相比，花生长单元的相对频率更高，这降低了水分胁迫下隔年结果的倾向。在水分胁迫下观察到的加速个体发育趋势表明营养生长较低，这反过来可能有利于花芽诱导和坐果。
