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.

中文翻译：

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智利温带和亚热带山谷休眠葡萄芽耐寒性的 Ferguson 模型测试

已开发出动态热时间模型 (DTTM) 来预测休眠葡萄芽的耐寒性，该模型使用日平均温度作为唯一的输入变量。然而，最近有报道称，葡萄芽的耐寒性不仅取决于低温 (LT)，还取决于植物植物激素脱落酸 (ABA) 的含量。DTTM 中的一个重要参数是生态环境边界 (EDB)，它表示芽从内环境到生态环境所需的寒冷度天数 (DDc)。在这项研究中，葡萄藤的芽耐寒性是通过亚热带埃尔基和智利温带迈坡山谷的低温放热 (LTE) 来测量的，并且该值适合 DTTM。此外，在整个休眠季节测定休眠芽中的 ABA 含量。结果表明，DTTM在迈坡比在Elqui山谷效果更好，并且在Elqui山谷种植的葡萄藤中，芽中ABA的含量更高。另一方面，优化后的 EDB 参数值在估计为冷蓄积时逐年变化，但当估计为时间时，在迈坡河谷保持不变。基于结果，我们得出以下结论：(a) DTTM 的正常运行要求休眠芽中的 ABA 含量曲线应每年保持不变，(b) 收集的芽中 ABA 的最高含量在 Elqui 山谷可能是由于非生物胁迫，（c）EDB 参数对应于累积的寒冷，直到芽开始去驯化过程之前，直到它们从内休眠中释放出来，