在研究生物超弱光子辐射机理的基础上，建立了大豆愈伤组织超弱光子辐射的双指数模型。用20 μW/cm2的UV-B辐射处理大豆愈伤组织2 h，测定处理后4 d内的超弱光子辐射。结果显示，双指数模型准确描述了大豆愈伤组织的超弱光子辐射及其在UV-B辐射下的变化，表明大豆愈伤组织的超弱光子辐射由快项和慢项两个部分组成；通过对双指数模型的分析得到了大豆愈伤组织自发发光与延迟发光中的初始光子数、积分强度和快项与慢项两个部分的衰减参数，由这些发光信息可以实现对大豆愈伤组织超弱光子辐射变化的定量分析。研究结果还发现，在UV-B辐射处理后的4 d内，延迟发光的快项部分发生了剧烈变化，自发发光出现了相反的变化趋势，暗示大豆愈伤组织超弱光子辐射对UV-B辐射反应灵敏的是延迟发光中的快项部分，细胞膜脂过氧化可能是造成快项部分剧烈变化的原因。

Double-exponential model of ultraweak photon emission of soybean callus was proposed based on the mechanism of ultraweak photon emission in biological system. Treated soybean callus by UV-B radiation(20 μW/cm2 )for 2 h，ultraweak photon emission of soybean callus treated by UV-B for 4 d after was measured. The results show that double-exponential model accurately describes the characteristics of ultraweak photon emission of soybean callus and its changes, delayed luminescence of ultraweak photon emission of soybean callus is composed by both fast and slow phase. Spontaneous luminescence in ultraweak photon emission of soybean callus and some parameters of delayed luminescence such as initial photon number I(0), integrated intensity I(T) and decay parameters of delayed luminescence are obtained through analysis of the double-exponential model, the characteristics of ultraweak photon emission of soybean callus can be quantitative expressed by these parameters. The studies also find that there is an excellent positive correlation between initial photon number I(0) and integrated intensity I(T)，and I(0) or I(T) can be used to measure the metabolic intensity of soybean callus. Induced by UV-B radiation(20 μW/cm2 ) for 2 h，the decay parameter of fast phase in delayed luminescence decreases first and then increases, the change of spontaneous luminescence is opposite, it suggests that fast phase of delayed luminescence is sensitive to the UV-B radiation and membrane lipid peroxidation could be the reason of the drastic change of fast phase in delayed luminescence of soybean callus.