Thermal methods for measuring the sap flow of common camellia

Hardy plants can maintain their normal physiological metabolism in cold winter and against the cold weather by regulating themselves. Around this natural phenomenon, a large number of researchers conducted researches on cold resistance of hardy plants and the mechanism of cold resistance respectively from the point of cell membrane structure and characteristics, physiological metabolism, growth environment stress and so on. However, the cold resistance of plants is the quantitative trait of micro‒effect multifactor control, which has complex properties. So no convincing results have been obtained so far. Norbert Wiener has proposed in Cybernetics that: Life is first a heat engine. The energy conversion and utilization process of living organisms does not conform to Carnot Theorem for the temperature difference between living organisms and the surrounding environment is very small.1 Although the theory is aimed at human tissues, plants also have physiological metabolism in the process of growth and adapt to the surrounding environment. As an efficient open thermodynamic system, plants themselves are also a “heat engine”, which has their own thermodynamic principle. Therefore, it can analyze the anti‒cold mechanism of plants from the perspective of thermal response.