Effect of light microclimate on the quality of 'd'Anjou' pears in mature open-centre tree architecture

Light availability within trees is an important factor for canopy and fruit development as light drives photosynthetic processes. The effect of pre-harvest light microclimate on 'd'Anjou' pear fruit quality from harvest through to cold storage and ripening on fruit grown in open vase pear tree canopy was investigated. Light penetration was used to determine the light availability at different positions within the tree canopy. Five light penetration levels were predefined as 0-20%, 20%-40%, 40%-60%, 60%-80%, and 80%-100% and 60 fruits were selected from each level for quality assessment during three-month cold storage and postharvest ripening period. At harvest, upper canopy portions had a greater number of fruit than lower portions, but average single fruit mass was similar. During the cold storage and ripening period, the IAD index, a measure of chlorophyll degreening indicating fruit maturity, decreased. Fruit mass decreased for all light penetration levels during cold storage. No significant difference was found in fruit mass between light penetration levels following cold storage. Fruit soluble solids increased with light penetration while firmness exhibited an inverse relationship with light penetration level. Fruit from 80% to 100% light penetration level had significantly lower titratable acidity compared to other levels. This study indicated that light microclimate had consequential effects on 'd'Anjou' pear fruit quality, and effects of light penetration on quality were most pronounced in extreme light conditions, which are suggested to be the focus of further research.