A dynamic thermal time model (DTTM) has been developed to predict cold-hardiness in dormant grapevine buds, which uses daily mean temperatures as the only input variable. However, it has been recently reported that cold-hardiness in grapevine buds depends not only on low temperatures (LTs), but also on the content of the plant phytohormone abscisic acid (ABA). An important parameter in the DTTM is the ecodormancy boundary (EDB), which represents the chilling degree days (DDc) required for the transition of the buds from endo to ecodormancy. In this study, the bud cold-hardiness of grapevines was measured by the low-temperature exotherm (LTE) in the subtropical Elqui and in the temperate Maipo valleys of Chile, and the values fitted to the DTTM. Moreover, the ABA content was determined in dormant buds throughout the dormant season. The results demonstrated that the DTTM worked better in the Maipo than in the Elqui valley, and that the content of ABA in the buds was higher in the vines grown in the Elqui valley. On the other hand, the optimized EDB parameter value varied from year to year when it was estimated as chilling accumulated, but when it was estimated as time, it remained constant in the Maipo valley. Based on the results, we conclude the following: (a) the proper functioning of the DTTM requires that the ABA content profile in the dormant buds should be kept constant from year to year, (b) the highest content of ABA in the buds collected in the Elqui valley is probably due to abiotic stresses, (c) the EDB parameter corresponds to the accumulated cold until before the buds begin their deacclimation process and not until they release from endodormancy, (d) the release of the buds from endodormancy does not depend on the accumulated cold, but on the elapsed time.

译文

已经开发了动态热时间模型 (DTTM) 来预测休眠葡萄芽的抗寒性,该模型使用每日平均温度作为唯一的输入变量。然而,最近有报道说,葡萄芽的抗寒性不仅取决于低温 (LTs),还取决于植物激素脱落酸 (ABA) 的含量。DTTM中的一个重要参数是ecoodormancy边界 (EDB),它表示芽从endo过渡到ecoodormancy所需的冷藏天数 (DDc)。在这项研究中,通过亚热带Elqui和智利温带Maipo山谷的低温放热 (LTE) 测量了葡萄藤的芽抗寒性,其值适合DTTM。此外,在整个休眠季节中确定了休眠芽中的ABA含量。结果表明,DTTM在Maipo中比在Elqui山谷中效果更好,并且在Elqui山谷中生长的葡萄藤中芽中ABA的含量更高。另一方面,优化的EDB参数值在估计为累积的寒流时逐年变化,但在估计为时间时,在Maipo山谷中保持恒定。根据结果,我们得出以下结论 :( a) DTTM的正常功能要求休眠芽中的ABA含量分布每年应保持恒定,(b) 在Elqui山谷收集的芽中ABA的最高含量可能是由于非生物胁迫造成的,(c) EDB参数对应于累积的寒冷,直到芽开始其去适应过程,直到它们从endodormancy释放出来,(d) 芽从endodormancy的释放不取决于累积的寒冷,而是取决于经过的时间。

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