Freezing is a typical abiotic stress on plants, which can induce physiological damages of plants. A better understanding of plant freeze-thaw characteristics contributes to solving some hot issues in plant physiology, such as cold resistance and cold acclimation. This article presents a novel sensor for in situ detection of freeze-thaw characteristics in plants based on stem temperature and water content. The measuring circuit of stem temperature was designed based on constant current source and platinum resistance. The measuring circuit of stem water content was designed based on standing wave ratio and the dielectric properties of stem tissue. The temperature resolution of the compound sensor is less than 0.1°C. The MAE and RMSE of temperature measurement are approximately 0.57°C and 0.65°C, respectively. The volumetric water content resolution of the compound sensor is less than 0.05%. The MAE and RMSE of volumetric water content measurement are approximately 1.59% and 1.81%, respectively. Moreover, a mathematical model for describing the freeze-thaw characteristics of plant stem was established and solved based on the compound sensor. Then, some freeze-thaw indicators including stem water content, ice content, freezing depth, freezing velocity, thawing depth, and thawing velocity were solved and used to interpret the freeze-thaw rules of plant stem. It can be concluded that the freeze-thaw velocity is closely related to the physicochemical properties of plant stem which also change dynamically in the freeze-thaw cycle.

中文翻译：

---

一种从茎温度和水分含量测量中就地检测植物冻融特性的新型传感器

冷冻是对植物的典型非生物胁迫，其可以诱导植物的生理损害。对植物冻融特性的更好理解有助于解决植物生理学中的一些热点问题，例如抗寒性和冷驯化。本文提出了一种新颖的传感器，用于根据茎温度和水分含量原位检测植物的冻融特性。基于恒流源和铂电阻设计了阀杆温度测量电路。根据驻波比和茎组织的介电特性设计了茎含水量的测量电路。复合传感器的温度分辨率小于0.1°C。温度测量的MAE和RMSE分别约为0.57°C和0.65°C。复合传感器的体积水含量分辨率小于0.05％。体积水含量测量的MAE和RMSE分别约为1.59％和1.81％。此外，基于复合传感器建立并求解了描述植物茎的冻融特性的数学模型。然后，求解了包括茎干含水量，冰含量，冻结深度，冻结速度，解冻深度和解冻速度在内的一些冻融指标，并将其用于解释植物茎的冻融规律。可以得出结论，冻融速度与植物茎的理化性质密切相关，其在冻融循环中也动态变化。分别为81％。此外，基于复合传感器建立并求解了描述植物茎的冻融特性的数学模型。然后，求解了包括茎干含水量，冰含量，冻结深度，冻结速度，解冻深度和解冻速度在内的一些冻融指标，并将其用于解释植物茎的冻融规律。可以得出结论，冻融速度与植物茎的理化特性密切相关，其在冻融循环中也动态变化。分别为81％。此外，基于复合传感器建立并求解了描述植物茎的冻融特性的数学模型。然后，求解了包括茎干含水量，冰含量，冻结深度，冻结速度，解冻深度和解冻速度在内的一些冻融指标，并将其用于解释植物茎的冻融规律。可以得出结论，冻融速度与植物茎的理化特性密切相关，其在冻融循环中也动态变化。求解了解冻速度和解冻速度，并用于解释植物茎的冻融规律。可以得出结论，冻融速度与植物茎的理化特性密切相关，其在冻融循环中也动态变化。求解了解冻速度和解冻速度，并用于解释植物茎的冻融规律。可以得出结论，冻融速度与植物茎的理化特性密切相关，其在冻融循环中也动态变化。