SHADING TIMING AND INTENSITY INFLUENCES FRUIT-SET AND YIELD IN CRANBERRY

Cranberry (Vaccinium macrocarpon Git.) vines were shaded with either 72% or 93% shadecloth (28% or 7% of full sun) for 1 month before flowering, after flowering, or before harvest, Fruit set was reduced by heavy shade (93%) before flowering in 1991 but not in 1999 or 1993. Heavy shade following flowering reduced fruit set in 1991 and 1992 but not 1993. The number of flowers per upright was generally not affected by shading but was reduced by prebloom shading at either level in 1993. Mean berry weight was usually conserved. Yield was reduced by shading at either level following flowering in 1991 and 1992. Shading just before harvest had no effect on the characteristics measured, Total nonstructural carbohydrate concentration was reduced to about half relative to the controls by either shading level at all treatment dates, Carbohydrate concentrations recovered to control levels by 4 to 8 weeks following removal of shading, Shading always reduced carbohydrate concentrations but did not always reduce fruit set or yield.