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

C

ole dual

d

ispersion 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.