summary form only given. the objective of this study is to correlate ground bidirectional spectral reflectance data of cotton and rice field crops throughout their growing season with high-altitude remotely sensed data. using a hand-held spectroradiometer with four wavelength bands of the landsat multispectral scanner (mss) makes it possible to collect in situ temporal spectral measurements of the crops. green, red, and infrared reflectances are closely related to the agronomic and physiological properties such as plant height, crop cover percentage, green leaf biomass, and chlorophyll content of both crops. the decreased reflectance values in the infrared portion, particularly for rice during the maturity stage, are mainly caused by yellowing and dryness of rice plants. the reduction in the infrared reflection for rice canopies is, however, four times that of cotton in band six; the reduction is almost one-third that of cotton for submerged rice in band seven. the green/red ratio seems to be ineffective for vegetation discrimination. significant interrelationships have been established between infrared/red ratio, vegetation index, plant height, and crop cover percentage. therefore, monitoring the stages of crop development based on the vegetation index for cotton and rice is proposed, and five distinct and spectrally measurable stages are defined. the highest value of spectral reflectance was recorded for cotton using four bands of the radiometer