The chilling requirements (CR) [1] refer to the value of low temperature required for deciduous fruit trees to overcome their natural dormancy. It is an important quantitative index for measuring their dormant and dormant release characteristics. Only a deciduous fruit tree that satisfies a certain level of chilling requirements can break the dormancy and carry out a normal series of growth and development; otherwise, the germination, flowering, flower bud differentiation, fruit development, and yield will be adversely affected [2]. With the environmental pollution and global warming, the chilling requirements of fruit trees is affected, which leads to early germination, poor fruit development, small fruit volume and uneven ripening time, resulting in economic loss to farmers [3–6].
There are several models for calculating the chilling requirements. Based on their regularity, the models can be roughly divided into two types: distribution functions (type I) and dynamic models (type II). In type I, Weinberger [7] first proposed the low-temperature hour model (0–7.2), which is still widely used today. Some models have a smaller range of low temperature conversion than 0–7.2, so the calculation results conform well to the natural law. Due to the difference in temperature conversion range, some models such as North Carolina Model (NC) [8] and Positive Utah Model [9] are more effective for specific regions [10]. The dynamic model is different from other models in that it calculates chilling requirements through dynamic two-step processes [11–13]. In this model, since more factors are considered than other models, and the repeatability is excellent in both cold and warm regions, it is regarded as the best model [6]. However, due to its complexity, its application is limited.
At present, there is no independent interface visualization tool for the calculation of cooling demand. The traditional treatment method makes the statistics difficult for researchers and fruit growers. The developed CHR is an entirely independent tool. It offers robust statistical results for different models, only by providing temperature data. CHR carries out simple analysis and drawing functions to implement the rules of each model.