RELATIVE SENSITIVITY OF DISTRICT MEAN RVI AND NDVI OVER AN AGROMETEOROLOGICAL ZONE

The higher sensitivity of RVI to crop status, as compared to NDVI, during early vegetation and maturity phases enables RVI to be used synergistically with NDVI in studying agrometeorological relations of crop growth. The paper discusses the sensitivity of mean RVI/NDVI ratio (scaling factor: 1.493) with reference to Geographic Area under Agriculture (GAA) and Agriculture Area under Wheat (AAW). During initial vegetative stages the RVI/NDVI ratio was nearly same for all the districts. During near flat peak NDVI response phase this ratio was in 1.322-1.415, 1.379-1.588 range for GAA values in 68.85-76.77% and 61.90-64.41% (AAW>84%) range, respectively; the districts with 40.61-49.47% (AAW:67-86.49%) and 26-30% GAA (AAW:60-74%) had wider range of 1.462-1.809 and 1.507-2.055, respectively. The ratio of standard deviation for RVI and NDVI during peak response phase exceeded 0.837 value only for districts with GAA>88% and AAW>89%. Synergistic use of RVI and NDVI would pay where mean ratio range<scaling factor.