On spectral indices as a function of soil variability in safflower crop |
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| Authors: | T N Hajare N G Patil K S Verma |
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| Institution: | (1) Agricultural Faculty, Agricultural Structures and Irrigation Department, Ondokuz Mayıs University, Kurupelit, Samsun, Turkey;(2) Ankara Soil and Water Resources Research Institute, Lodumlu, Ankara, Turkey |
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| Abstract: | Spectral indices as an indicator of physiological traits affecting safflower yield in relation to soil variability were evaluated
in a two year experiment (1997–1999). Reflectance, biometric and phonological data were collected. Two indices namely normalized
differential vegetation index (NDVI) and ratio of spectral reflectance in infrared region to red region (1R/R) were derived
from radiometric observation. Yield data indicated significant difference in different soils. Temporal NDVI behaviour as a
function of soil type was not prominent especially in early stages of crop growth. However NDVI at 75 days after sowing (DAS)
was found to be relatively better indicator of plant status and yield. IR/R was relatively less effective in indicating the
differential response of crop to soil types. Effect of soil and crop interaction on spectral indices was significant at 75
and 90 DAS, which was attributed to attainment of maximum leaf area and leaf area at these stages of growth. Regression analysis
showed strong positive relationship between NDVI and leaf area, dry matter and yield. IR/R and leaf area had the strongest
and consistent relationship (r = 0.96). A single regression equation accounted for yield variability in the dataset. Thus
possible transformation of NDVI maps (satellite data) to LAI units and consequently applications like yield forecasting was
indicated. Utility of spectra-temporal data as a pointer of plant development status and yield was also demonstrated. |
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