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Spectral characteristics of Tomato (lycopersicon esculentum mill.) in different sowing dates
J. Mukherjee and C. V. S. Sastri
Division of Agricultural Physics,
Indian Agricultural Research Institute,
New Delhi – 110 012
Field experiment was conducted in IARI farm
during 1998-'99 and 1999-'00 spring summer for evaluation of spectral response of tomato
crop. Six different spectral indices (IR/R, NDVI, hVI, hNDVI, BNI and GNI) were computed to
characterize the spectral pattern of tomato crop. Spectral reflectance of crop canopy was
taken by spectroradiometer (LICOR 1800) in ten days interval. To characterize plant growth
LAI, dry biomass, and plant height were taken and CGR was calculated. In general, it was
observed that value of all the indices was more incase of first sowing than second and third
sowing due to higher biomass, LAI and plant height in first sowing compared to late sowing.
Value of all the indices (except BNI) increased with days after transplanting (DAT) of crop
up to 80-90 DAT after that it decreased. After attaining peak value of all indices a
constant value was observed due to indeterminate growth of vegetables crop. Little
decreasing trend was observed due to yellow colouration of leaves at the final harvest
stage. Among the three cultivars, cultivar Pusa Sheetal recorded highest values in both the
seasons. And first season's crop recorded highest value of all the indices than second
season as first season' crop had higher biomass, LAI and plant height and higher fruit
yield. Among the all six indices NDVI gave highest correlation with dry plant biomass, LAI
and plant height. The peak values of NDVI recorded were 0.699 to 0.799 among all the three
cultivars. Regression model was developed for prediction of both yield and dry biomass using
spectral indices.
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