G.M. Colavita, V. Blackhall, S. Valdez
The quality and the conservation of fruit exposed to high solar radiation are affected by a physiological disorder caused by oxidative stress, called solar injury or sunburn. A Kaolin (chemically inert clay) particle film reflects solar radiation and reduces the heating and oxidation of the fruit. The effect of the kaolin particle film on fruit surface temperature (FST), fruit quality and vegetative parameters were studied on Pyrus communis ‘Packham’s Triumph’ (PT) and ‘Beurre d’Anjou’ (BDA). This study was conducted at the Comahue National University (38°56’S; 67°59’W), Argentina. Treatments began on 1 December 2005, with applications every two weeks of DuoprotectTM (95% kaolin) in aqueous solutions of 3 and 6% (w/v) concentration, with a calibrated air-blast sprayer to apply 2000 L ha-1. These treatments were compared with an untreated control. Increasing concentrations of kaolin from 3 to 15% reduced the FST between 1.6 and 4.7°C; the reduction was not in a linear proportion to the applied concentration. Treated fruit showed 10% lower electrolyte leakage and, therefore, the cellular membrane damage was less than in the control. Solar injury was significantly reduced in PT with 66.8, 71.1 and 81.5% for fruit without damage for concentration 0, 3 and 6% respectively. The reduction of sunburn increased the superior quality of BDA pears 8.6 and 26.3% for concentrations of 3 and 6%, respectively. Treatments did not affect fruit firmness, starch index, soluble solid concentration, fresh weight or vegetative parameters on BDA pears, but in PT pears they increased fresh weight and chlorophyll contents. The white kaolin film may be an effective treatment in reducing sunburn in pears, increasing their quality and benefiting the whole tree.
Colavita, G.M., Blackhall, V. and Valdez, S. (2011). EFFECT OF KAOLIN PARTICLE FILMS ON THE TEMPERATURE AND SOLAR INJURY OF PEAR FRUITS. Acta Hortic. 909, 609-615
DOI: 10.17660/ActaHortic.2011.909.73
Pyrus communis, sunburn, heat-stress, high solar radiation, fruit quality, chlorophyll

Acta Horticulturae