C. Rinallo et B. Mori, DAMAGE IN APPLE (MALUS-DOMESTICA BORKH) FRUIT EXPOSED TO DIFFERENT LEVELS OF RAIN ACIDITY, Journal of Horticultural Science, 71(1), 1996, pp. 17-23
The effects of rain acidity on fruit of field-grown apple trees (Malus
domestica Borkh) cv. Summerred were investigated. One group of four t
rees was exposed to ambient rainfall, while four other groups were cov
ered with rain shields and received simulated rain consisting of deion
ized water or an acid solution at pH 5.6, 4.0 or 3.0. SEM examination
showed alterations of the cuticular wax and russeting of the skin. For
mation of a cambium, which in turn brought about the formation of a ph
ellem layer as a substitution for the damaged epidermis and hypodermis
, was evident. Necrosis and lesions on fruit mesocarp were also observ
ed. Simulated acid rain at pH 4.0, and particularly at pH 3.0, damaged
fruit and impaired its marketability. The acidity of ambient rainfall
and simulated acid rain at pH 5.6 caused negligible damage.