Light distribution oncitrus canopyaffects physiological parameters and fruiting pattern

Light interception by the orange tree canopy during flower bud differentiation and subsequent flowering and fruit setting has been monitored by continuous data recording from 48 silicon cells distributed in different canopy zones. Two experimental conditions have been tested: trees artificially shaded by a black nylon net cage, and non-shaded trees. Observations were made on the total radiation accumulated in the different canopy zones, and they were related to photosynthetic activity, stomatal conductance) flowering and fruiting pattern, and fruit quality. The different light distribution affected both photosyntesis and stomatal conductance: in fact, they were both drastically reduced in shaded trees, and a significant decrease was also found in both shaded and unshaded trees in relation to different canopy zones. A significant decrease of flowering and fruit setting was found from the top of the canopy to the bottom and from outside to inside, in relation to the different amount of radiant energy availability. Finally significant differences were found on fruit quality.