Chmielewski Frank-M, Götz Klaus-Peter
Agricultural Climatology, Faculty of Life Sciences, Humboldt-University of Berlin, Albrecht-Thaer-Weg 5, 14195 Berlin, Germany.
Plants (Basel). 2022 Aug 4;11(15):2044. doi: 10.3390/plants11152044.
Models used to predict the onset of fruit tree blossom under changed climate conditions should be physiologically based as much as possible. Pure optimized phenology models carry the risk of unrealistic predictions due to a misinterpretation of metabolic processes. This was the motivation determining the relevant phases for chill and heat accumulation, which induces cherry blossom (cv. Summit). Investigations are based on 8 years of observational and analytical data, as well as on controlled experiments. For 'Summit' buds, to be released from endodormancy, 43 chill portions from 1 September are necessary. After endodormancy release (t), on average on 30 November, no further chilling is required, because no correlation between chill accumulation during ecodormancy and the subsequent heat accumulation until 'Summit' blossom exist. The declining amount of heat, which induces cherry blossom after t-shown in several forcing experiments-seems to be the result of the declining bud's abscisic acid (ABA) content, up to ~50% until the beginning of ontogenetic development. Shortly after t, when the bud's ABA content is high, a huge amount of heat is necessary to induce cherry blossom under controlled conditions. Heat requirement reduces during ecodormancy along with the reduction in the ABA content. According to these findings, plant development during ecodormancy is suppressed by low temperatures in the orchard and a slowly declining bud's ABA content. These results should lead to a better consideration of the ecodormancy phase in phenology models.
用于预测气候变化条件下果树开花时间的模型应尽可能基于生理学原理。单纯的优化物候模型存在因对代谢过程误解而导致预测不切实际的风险。这就是确定诱导樱花（品种为Summit）的低温和热量积累相关阶段的动机。研究基于8年的观测和分析数据以及对照实验。对于Summit品种的芽，要从内休眠状态解除，从9月1日起需要43个低温单位。在内休眠解除后（t），平均在11月30日，不再需要进一步的低温，因为在生态休眠期间的低温积累与随后直到Summit开花的热量积累之间不存在相关性。在几个催花实验中显示，t之后诱导樱花的热量量下降，这似乎是芽中脱落酸（ABA）含量下降的结果，在个体发育开始前下降至约50%。在t之后不久，当芽的ABA含量较高时，在控制条件下诱导樱花需要大量热量。在生态休眠期间，随着ABA含量的降低，热量需求也会减少。根据这些发现，果园中的低温和芽中ABA含量的缓慢下降会抑制生态休眠期间的植物发育。这些结果应能使物候模型更好地考虑生态休眠阶段。
