Department of Botany, University of Innsbruck, Sternwartestraße 15, A-6020, Innsbruck, Austria.
Université Clermont Auvergne, INRA, PIAF, F-63000, Clermont-Ferrand, France.
Plant Cell Environ. 2018 May;41(5):1008-1021. doi: 10.1111/pce.12935. Epub 2017 Apr 19.
Frost damages develop when exposure overtakes frost vulnerability. Frost risk assessment therefore needs dynamic simulation of frost hardiness using temperature and photoperiod in interaction with developmental stage. Two models, including or not the effect of photoperiod, were calibrated using five years of frost hardiness monitoring (2007-2012), in two locations (low and high elevation) for three walnut genotypes with contrasted phenology and maximum hardiness (Juglans regia cv Franquette, J. regia × nigra 'Early' and 'Late'). The photothermal model predicted more accurate values for all genotypes (efficiency = 0.879; Root Mean Standard Error Predicted (RMSEP) = 2.55 °C) than the thermal model (efficiency = 0.801; RMSEP = 3.24 °C). Predicted frost damages were strongly correlated to minimum temperature of the freezing events (ρ = -0.983) rather than actual frost hardiness (ρ = -0.515), or ratio of phenological stage completion (ρ = 0.336). Higher frost risks are consequently predicted during winter, at high elevation, whereas spring is only risky at low elevation in early genotypes exhibiting faster dehardening rate. However, early frost damages, although of lower value, may negatively affect fruit production the subsequent year (R = 0.381, P = 0.057). These results highlight the interacting pattern between frost exposure and vulnerability at different scales and the necessity of intra-organ studies to understand the time course of frost vulnerability in flower buds along the winter.
当暴露时间超过抗寒能力时，霜害就会发展。因此，霜害风险评估需要使用温度和光周期对霜寒进行动态模拟，并与发育阶段相互作用。使用五年的抗寒监测数据（2007-2012 年），在两个位置（低海拔和高海拔），对三个具有不同物候和最大抗寒能力的核桃基因型（Franquette 品种的 Juglans regia cv、J. regia×nigra‘Early’和‘Late’），对包括或不包括光周期效应的两种模型进行了校准。光热模型对所有基因型的预测值更为准确（效率=0.879；预测值的根均方标准误差（RMSEP）=2.55°C），而热模型的效率为 0.801（RMSEP=3.24°C）。预测的霜害与冻结事件的最低温度高度相关（ρ=-0.983），而与实际抗寒能力（ρ=-0.515）或物候阶段完成率（ρ=0.336）相关性较低。因此，在冬季和高海拔地区，预测的霜害风险更高，而在早期基因型中，春季仅在低海拔地区有风险，因为它们的去寒化速度更快。然而，尽管早期霜害的价值较低，但可能会对次年的果实产量产生负面影响（R=0.381，P=0.057）。这些结果突出了在不同尺度上霜害暴露和脆弱性之间的相互作用模式，以及有必要进行器官内研究，以了解花蕾在冬季期间的霜寒脆弱性的时间进程。
