Estimating Cotton FPAR Based on the Different Vegetation Indexes

Two field experiments were conducted with different densities and waters,the relationship was analyzed between spectral reflectance and the fraction absorption of photosynthetically active radiation(FPAR),and the estimating models were established for FPAR in the whole growth stages of cotton.The results indicated that it was significant correlations among the FPAR with all the vegetation indexes,the green normalized difference vegetation index(GREENNDVI) and the reflectance ratio(GMI) was better,theirs correlations coefficient(r) were 0.794 and 0.765,respectively,the estimated models of FPAR were established,and the determination coefficients(r2) were 0.657 and 0.633,the root mean square errors(RMSE) were 0.089 and 0.093,respectively.The results suggested that the FPAR can be effectively estimate by spectral parameters during growth stages of cotton.