Crop Coefficient for Coffee as a Function of Leaf Area Index

This study was conducted in an experimental site at the Federal University of Lavras, Brazil, to estimate the single crop coefficient (K_c) for drip-irrigated coffee (Coffea arabica) and provide a mathematical description based on leaf area index (LAI). The cultivar used was Catiguá MG-3 planted in May 2007 with a spacing of 2.5 ± 0.6 m. The LAI were obtained from the average of plant height and canopy diameter with data derived from bimonthly measurements between 2007 and 2013. K_c values were determined from crop evapotranspiration (ET_c) and reference evapotranspiration (ETo). ET_c was estimated from the water balance between the periods of successive irrigations in which there was no precipitation, while ETo was obtained using the Penman–Monteith equation parameterized by FAO. To describe the relationship between K_c and LAI, linear and nonlinear models were used. The logistic model was best for describing the K_c values as a function of LAI. The determined minimum, mean and maximum K_c values were 0.21, 0.57 and 0.80 respectively.