Taylor et al. supportinginformation 
S1)Equations used forestimation of referencecrop evapotranspiration (ET0)
PET (potential evapotranspiration, mm d−1) was derived from dailymean values calculated from 
weatherstation data.  With the exception ofthe approximation madeforincomingsolar radiation 
(Rs), which is based on information on p. 22 of Jones (1992), the methods follow 
recommendations madebyAllen et al. (1998)for the calculation ofreferencecrop 
evapotranspiration (ET0). Thesemethods assumea ‘hypothetical referencecrop with an assumed 
crop height of 0.12 m, a fixed surfaceresistanceof 70 s m−1 and an albedo of0.23 reference
surface’(Allen et al., 1998)and meterological measurements madeat 2 m height abovethe 
groundsurface.  Theresult is that aerodynamicresistancera (s m
−1) has the approximation 
208/w, wherew =windspeed (m s−1). 
    
          
   
       
   
          
         
Tairisdailymean air temperature(°C), theaverageof dailymaximum (Tmax, °C) and 
minimum airtemperatures (Tmin, °C):
    
       
 
            
w is dailymean windspeed at 2 m (m s−1), calculated similarlyto dailymean temperature.  
                    
esis dailymean saturation vapour pressure(kPa), the averageof saturation vapour pressures at 
dailymaximum (Tmax, °C) and minimum airtemperatures (Tmin, °C):    
          
 
            
             
      
       
              
ea is actual vapour pressure(kPa), calculated based on dailymaximum (RHmax, %)and minimum  
(RHmin, %)relative humidities:
   
      
    
           
   
   
 
          
ε is the slope ofvapour pressurecurve(kPa°C−1):
  
             
        
        
 
           
          
γ is thepsychrometric constant (kPa°C−1):
                         
Pis air pressure(kPa): 
        
         
   
 
   
            
z =siteelevation (630 m) 
Rnet is net radiation (MJ m
−2 d−1), calculated as the differencebetween net solarradiation (Rns, 
MJ m−2 d−1) and net longwaveradiation (Rnl, MJ m
−2 d−1):
                                             
αis thealbedo ofthe crop, 0.23 forthe referencecrop 
Rsis thesolar radiation (MJ m
−2  d−1), approximated as shortwaveirradiance, calculated from 
integrated dailyPPFD (μmol m−2 d−1) on thebasis of information presented in Jones (1992; 
Table 2.2): 
   
    
            
               
     
    
      
 
 
                 
  
   
                   
σ is the Stefan-Boltzmann constant: 4.903 10−9 MJ K−4 m−2 d−1 
Tmin,K and Tmax,K arethe dailyminimum and maximum temperatures (K), respectively: 
                      
Rso is theclear skyradiation (MJ m
−2 d−1):
                        
asand bsareAngstrom constants: 0.25 and 0.5 respectively 
Ra is theextraterrestrial radiation (MJ m
−2 d−1):
   
      
 
                                            
πis 3.141593
Gsc is thesolar constant: 0.082 MJ m
−2 min−1 dris theinverserelative distanceEarth-Sun: 
            
 
   
                
Jis theJulian day
ωsisthe sunset hour angle(rad):
                      
φis thelatitudeof theexperimental site in this study: −0.5784021 rad 
δ is solardeclination (rad): 
          
 
   
                    
References 
Allen RG, PereiraLS, Raes D, Smith M (1998)Crop evapotranspiration -Guidelines for 
computing crop water requirements -FAOIrrigation and drainage paper 56. Rome, 
FAO-Food and AgricultureOrganization ofthe United Nations. 
Jones HG(1992)Plants and microclimate:a quantitativeapproach to environmental plant 
physiology. Cambridge, United Kingdom, CambridgeUniversityPress.