利用植被介电常数的Debye-Cole双频色散模型，模拟计算了广东肇庆水稻试验区1996年晚稻和1997年早稻人插秧期、发蘖期、扬花期到成熟期各生长期的介电常数值，并根据计算结果，探讨了电磁波频率、水稻含水量、温度、含盐度及水稻冠层干体密度对介电常数的影响。其中，不同生长期水稻的介电常数各不相同，不同水稻类型（早稻和晚稻），介电常数的变化趋势不尽相同。电磁波频率、水稻含水量、温度和水稻冠层干体密度均对介电常数有不同程度的影响，而含盐度却对介电常数影响不大。

Rice is a vital world food crop, and most paddy rice fields distribute in warm, humid environmental regions with heavy cloud cover and rainfall. It is difficult to acquire optical remote sensing data in these regions. So SAR system is used to map and monitor rice crop growth status. It is important for rice monitoring to understand the microwave backscattering. The backscattering is related to the dielectric properties and geometric parameters besides the radar system parameters. The geometric parameters of the rice can be easily measured, but it is very difficult to get the dielectric constant from ground observation due to many influence factors. So it is necessary to compute the dielectric constant using models.\;This paper presents the modeling results of dielectric constants from different rice growth stages in Zhaoqing test site using Debye_Cole dual_dispersion mode of vegetation. In the test site, two crops of early season rice and late season rice are planted in 1997 and 1996, and the growing period of rice crop is divided into five major stages: transplant, seeding developing, ear differentiation, heading and mature period. Based on the results, the paper discusses the influences from microwave frequency, gravimetric moisture content of rice, temperature, salinity and bulk density of dry vegetation meterials on dielectric constant. The rice crops of different growth stages have the various dielectric constants, and the dielectric constants of early and late season rice crops show the diverse changes. The parameters, including microwave frequency, gravimetric moisture content of rice, temperature and bulk density of dry vegetation materials, have the influence on dielectric constant, but salinity has no effect on the dielectric constant.