A method is presented which offers a biological base to empirical methods of estimating crop yield from remotely sensed canopy reflectance. This method involves two basic espects

（i） A pattern of leaf area index （LAI）

which follows a characteristic trajectory

is provided based on six sets of LAI from plant initiation to maturity from Boerema in Riverna

New South Welse

Australia. There are three varities each for the both of combine sowing and aerial sowing

（ii） A form of daily rate of intercepted photosynthetically active radiation （PAR）

IPARd

as a function of LAI is derived with a simulating calculation based on the radiation transfer equation in a canopy and the measured data of foliage inclination in the field and the conventional data of radiation. The simulated IPARd is tested with the measured points in the field in January. They are fitted very well. If a single value

LAl0

of LAI at the stage closely prior to anthesis is obtained

the values of LAI from then to maturity can be estimated based on the pattern of LAI. The accumulated intercepted PAR

TIRAR

from anthesis to maturity can then be estimated based on the function of IPARd. and estimated sequential LAI over this period. Then rice yield can be estimated from the TIPAR

assuming that all assimilates during this phase are directed towards seed-fillings.The method is used for estimating rice yields on farms. The values of LAlo are derived from the canopy reflectance on images of Landsat -5 on January 21

1985.