Abstract Frost damage significantly restrains global wheat production. Frost development is well documented at the landscape scale but inadequately studied at the sub-paddock scale. Particularly at sites with flat topography, which are where frost field trials are conducted. In these trials, wheat varieties are compared for frost resistance with researchers assuming minimum air temperature (frost severity) is relatively uniform. But previous research has suggested that this assumption leads to falsely identifying frost resistance. Here, we demonstrate how fibre-optic Distributed temperature sensing DTS can be used to measure nighttime temperatures in a wheat crop, to better understand frost development in field trials. DTS uses the Raman Effect and the scattering of laser light to measure temperature continuously across a fibre-optic cable providing temperature data with high spatial and temporal resolution. We demonstrate that DTS can be used to record nighttime temperature in a frost field trial with an average accuracy of 0.105 °C across 3487 m by constructing a fibre-optic fence with eight rungs, spaced at 100 mm increments from ground level, through seven blocks of wheat with different sowing times. Our research shows that even in mild frost events, vertical temperature gradients of 0.24 °C per 100 mm develop in wheat crops, with the coldest temperatures occurring ∼100 to 200 mm below the top of the ear. We also show that cold temperature development during frost is non-uniform but spatially organised in a sowing block of two varieties (Wyalkatchem and Elmore). In a sowing block there was up to a 1.3 °C range in minimum air temperature and a 5.0 °C hr (degree hours below 0 °C) variation in cold. Whereas, across the site, there was a 0.5 °C range in minimum temperature, and a 3.7 °C hr range between sowing blocks.The larger variation in minium temperature within than between sowing blocks suggests that trial design may have a greater impact on the development of cold temperature than topographic or soil differences across flat sites. There is also a varietal impact on cold development with Wyalkatchem recording more degree hours below 0 °C than Elmore, and this is suggested as driven by morphometric differences (height, canopy density and closure).Our results provide an improved understanding of cold temperature development in field trials that will aid in the search for frost resistance. They may also help to better understand cold temperature-yield relationships so that the economic impact of frost to growers can potentially be predicted to enable effective post-event management decisions.

中文翻译：

---

应用光纤分布式温度传感了解霜冻小麦（Triticum aestivum）温度动态

摘要 冻害严重制约了全球小麦产量。霜冻发展在景观尺度上有很好的记录，但在亚围场尺度上研究不足。特别是在地形平坦的地点，这些地点是进行霜冻场试验的地方。在这些试验中，研究人员将小麦品种的抗冻性与假设最低气温（霜冻严重程度）相对一致的情况进行了比较。但之前的研究表明，这种假设会导致错误地识别抗冻性。在这里，我们展示了光纤分布式温度传感 DTS 如何用于测量小麦作物​​的夜间温度，以更好地了解田间试验中的霜冻发展。DTS 使用拉曼效应和激光散射来连续测量光纤电缆上的温度，从而提供具有高空间和时间分辨率的温度数据。我们证明了 DTS 可用于在霜场试验中记录夜间温度，通过构建一个具有 8 个梯级的光纤围栏，在 3487 m 范围内的平均精度为 0.105 °C，从地面以 100 mm 的增量间隔，穿过七个块不同播种时间的小麦。我们的研究表明，即使在轻度霜冻事件中，小麦作物也会产生每 100 毫米 0.24 °C 的垂直温度梯度，最冷的温度发生在耳朵顶部以下约 100 至 200 毫米。我们还表明，霜冻期间的低温发展是不均匀的，但在两个品种（Wyalkatchem 和 Elmore）的播种块中空间组织。在播种块中，最低气温最高可达 1.3 °C，寒冷的气温变化幅度高达 5.0 °C hr（低于 0 °C 的小时数）。而在整个场地，最低温度范围为 0.5 °C，播种块之间的最低温度范围为 3.7 °C hr。与播种块之间相比，最低温度变化更大表明试验设计可能对与平坦地区的地形或土壤差异相比，寒冷温度的发展。Wyalkatchem 在 0 °C 以下记录的度数小时数比 Elmore 多，这对寒冷发育也有品种影响，这表明这是由形态学差异（高度、冠层密度和封闭度）驱动的。我们的结果提供了对田间试验中低温发展的更好理解，这将有助于寻找抗冻性。它们还可能有助于更好地了解低温与产量的关系，以便可以预测霜冻对种植者的经济影响，从而实现有效的事后管理决策。