Abstract: The radiation use efficiency (RUE) model suggested by Monteith in 1972 is one of the most widely applied approaches for modeling net primary production and crop yield, especially by means of remote sensing techniques. To use this approach, RUE and harvest index (HI) are the two key parameters that need to be defined, besides the absorbed photosynthetically active radiation. However, there exist some problems in the studies and applications of RUE and HI. This paper reviewed the research progress on RUE and HI, summarized the current methods and procedures for  defining RUE and HI values when using the RUE approach for predicting crop yield by remote sensing, and proposed that in order to maximize the effective application of RUE and HI in remote sensing crop yield and crop production management, future researches should seek proper procedures to determine the spatial heterogeneities of RUE and HI at regional scale based on field experiments.

Key words: radiation use efficiency, harvest index, Epsilon approach, remote sensing of crop yield, saline wastewater, nitrification, extracellular polymeric substances (EPS), ammonium oxidize bacteria (AOB), nitrite oxidize bacteria (NOB).