Light saturation curves were developed for detached, non-fruiting `Stayman' and `Delicious' spur leaves from interior, middle, and peripheral canopy positions throughout the season in 1989 and 1990, respectively. Be inning at bloom, measurements were made every 2 weeks for the first 8 weeks, and monthly thereafter. SLW was calculated simultaneously with photosynthetic measurements. MacArthur-Wilson saturation equations were used with non-linear regression to fit the saturation curves and SLW data, and curves were compared using indicator variables. Even at bloom, saturation curves and SLW differed among positions. The peripheral position bad a greater saturation point and equilibrium rate throughout the season, and the interior and middle positions were equivalent by about 6 weeks after bloom.
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