The result showed that LAI, plant height, total dry matter and dry matter partitioning are correlated with radiance ratio (RR) and normalized difference vegetation index (NDVI). The correlation coefficient  ( r ) values are improved with second degree model ‘B’ over that of simple linear model ‘A’ and are further improved under multiple linear model ‘C’, in which ‘Days After Sowing’ was added as independent variable. Spectral indices and plant parameters except LAI and chlorophyll content are better correlated under Desi cotton as compared to American cotton and vice versa. The integrated spectral indices and growth variables are highly correlated during 51- 80 DAS (initiation of flowering to 50 per cent boll formation in American cotton and 25 per cent squaring to 25 percent of boll formation in Desi cotton). Yield attributes like number of flowers per plant, number of unopened bolls/plant, number of total bolls/plant are more significantly correlated with spectral indices during 81-110 DAS (50 per cent boll formation to 25 percent of boll opening) in American cotton. While in Desi cotton, number of unopened bolls/plant is highly significantly correlated with spectral indices during the same period i.e., 81-110 DAS (25 percent boll formation to initiation of boll opening).  It showed that the yield of American or Desi cotton could be estimated from spectral parameters during maximum vegetative growth stage i.e., 2-3 month before harvest with maximum 5 per cent deviation from actual yield.