ARS | Publication request: REFLECTIVE PARTICLE FILMS AFFECT PHOTOSYNTHESIS AND YIELD IN 'EMPIRE' APPLE

Submitted to: Journal American Society Hortscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2003
Publication Date: May 1, 2003
Citation: GLENN, D.M., EREZ, A., PUTERKA, G.J., GUNDRUM, P.G. REFLECTIVE PARTICLE FILMS AFFECT PHOTOSYNTHESIS AND YIELD IN 'EMPIRE' APPLE. Journal American Society Hortscience. 2003.

Interpretive Summary: Reflective, processed-kaolin particle films are used in horticultural crops to repel insects, and reduce heat stress and solar injury of fruit. The purpose of these studies was to determine the effect of two reflective, processed-mineral particle film materials, based on processed kaolin and calcium carbonate, on whole plant carbon assimilation, water use efficiency, yield, fruit size and quality in 'Empire' apple over a 4-year period of time. The application of a reflective, processed-kaolin particle film reduced canopy temperature, and presumably reduced environmental stress, resulting in increased fruit weight in all years of the study and increased red fruit color in 2 of 4 years. Whole canopy carbon assimilation studies indicated increased carbon assimilation only under conditions of high air temperature. The consequence of increased carbon assimilation by the processed-kaolin particle film was reduced water use efficiency likely due to increased stomatal conductance associated with reduced leaf temperature. Calcium carbonate demonstrated none of these effects. Calcium carbonate reflected more PAR than the processed-kaolin particle film. We concluded that the processed kaolin was a more effective than calcium carbonate as a particle film mineral and that the mechanism of enhanced yield was reduced canopy temperature that reduced heat stress.

Technical Abstract: Reflective, processed-kaolin particle films are used in horticultural crops to repel insects, and reduce heat stress and solar injury of fruit. The purpose of these studies was to determine the effect of two reflective, processed-mineral particle film materials, based on processed kaolin and calcium carbonate, on whole plant carbon assimilation, water use efficiency, yield, fruit size and quality in 'Empire' apple over a 4-year period of time. The application of a reflective, processed-kaolin particle film reduced canopy temperature, and presumably reduced heat stress, resulting in increased fruit-weight in all years of the study and increased red fruit color in 2 of 4 years. Whole canopy carbon assimilation studies indicated increased carbon assimilation only under conditions of high air temperature. The consequence of increased carbon assimilation by the processed-kaolin particle film was reduced water use efficiency likely due to increased stomatal conductance associated with reduced leaf temperature. Calcium carbonate demonstrated none of these effects. Calcium carbonate reflected more PAR than the processed-kaolin particle film.