Abstract:
Estimating crop coefficients and evapotranspiration (ET) accurately is crucial for optimizing
irrigation. Remote sensing techniques using green canopy cover, leaf area index (LAI), and normalized
difference vegetation index (NDVI) have been applied to estimate basal crop coefficients (Kcb) and
ET for different crops. However, analysis of the potential of these techniques to improve water
management in irrigated potato (Solanum tuberosum L.) is still lacking. This study aimed to assess
the modified nonlinear relationship between LAI, Kcb and NDVI in estimating crop coefficients
(Kc) and ET of potato. Moreover, Kc and ET were derived from the measured fraction of green
canopy cover (FGCC) and the FAO-56 approach. ET estimated from the FAO-56, FGCC and NDVI
approaches were compared with the ET simulated using the LINTUL-Potato model. The results
showed that the Kc values based on FGCC and NDVI were on average 0.16 lower than values based
on FAO-56 Kc during the mid-season growing stage. ET estimated from FAO-56, FGCC and NDVI
compared well with ET calculated by the LINTUL-Potato model, with RMSE values of 0.83, 0.79, and
0.78 mm day−1
, respectively. These results indicate that dynamic crop coefficients and potato ET can
be estimated from canopy cover and NDVI. The outcomes of this study will assist potato growers in
determining crop water requirements using real-time ETo, canopy state variables and NDVI data
from satellite images.
