The parameter F00 was estimated using an approximation by Oxborough and Baker (1997). Total leaf area (TLA), specific leaf weight (SLW) and relative water content (RWC) were used from leaves after monitoring gas exchange measures. TLA was determined using a scanner, Image leaf area measurement software (University of Sheffield, 2003), and dry weight. SLW was calculated from SLW =DW/TLA and the RWC was determined according to Turner (1981).