JIP-test parameters to study apple peel photosystem II behavior under high solar radiation stress during fruit development

Abstract

Changes in apple (Malus domestica Bork.) peel PSII photochemical process during fruit development under high solar radiation field conditions were analysed by the JIP-test to increase understanding on energy dissipation and susceptibility to photooxidative damage. Fruits growing exposed (E), non-exposed (NE) or suddenly exposed (SU) to high solar radiation were evaluated at three developmental stages. Chlorophyll content and chlorophyll a fluorescence transient (OJIP), were affected by high solar radiation and development. Minimum fluorescence, maximum fluorescence, maximum quantum yield of photochemistry, and specific fluxes per cross section decreased in E and SU fruits. JIP parameters were a sensitive indicator of high solar radiation stress in apple peel. Peroxidative damage was observed in E fruits at each stage of development and in SU fruits at early and mid-stages. By delineating the photochemical events induced by solar radiation in apple fruits at different developmental stages, our findings might help to increase understanding on susceptibility of apple to photooxidation damage depending on the light environment and developmental stage they are exposed to.