Evaluation Of Evaporation Measuring Methods For Reference Evapotranspiration within Greenhouse

Alternative methods for estimating reference evapotranspiration (ETo) within greenhouses are explored due to the large area occupied by a Class A pan. Based on the locations, the evapotranspiration difference between inside and outside greenhouse varies. Research results about what pan co-efficient (Kp) should be utilized inside the greenhouse are not conclusive. Therefore the main objective of the work was to compare ETo calculated by various methods within and outside a greenhouse. A Class A pan (CAPi), a reduced pan (RPi_60cmØ ) and a reduced pan (RPi_20cmØ ) were installed inside a greenhouse, and another Class A pan (CAPo) was installed outside. ETo estimates, obtained by CAPi, RPi_60cmØ and RPi_20cmØ were 54 per cent, 57 per cent and 59 per cent of those estimated by CAPo, respectively. A simple linear regression showed positive coefficients R = 0.76 for the CAP_ox CAP_i , R = 0.96 for the CAP_i and the RPi_60cmØ , R = 0.98 for the CAPi and the RPi_{20cm Ø} . The study concluded that it is possible to use reduced pans to estimate the ETo inside the greenhouse and replacement of reduced pan would increase the space available for cultivation in the greenhouse.