[Effects of bagging on light use efficiency of tomato fruit photosystem II]

In a greenhouse experiment, white laminating bags were applied to bag the tomato cultivar 'Baoluota' fruits, with the absorption spectra and chlorophyll fluorescence parameters of the fruits measured by optical spectrometer and Mini-Imaging-Pam after different bagging time, aimed to investigate the effects of bagging on the light use efficiency of photosystem II of the fruits. In the first 20 days of bagging, no significant effects of bagging were observed on the chlorophyll a (Chl a) content and the maximum quantum yield of PS II (Fv/Fm) of the fruits, but the relative absorption coefficient (A(670/780)) and the effective quantum yield of PS II (Y(II)) were reduced, compared with the control. In this period, the regulatory energy dissipation of PS II played, an important role. After then, the Chl a and Chl b contents of bagged fruits decreased markedly, but the Fv/Fm, Y(II), and A(670/780) had no significant differences with the control. On the 40th day of bagging, the Chl a and Chl b contents of bagged fruits decreased by 35.2% and 52.8%, but the Fv/Fm and Y(II) increased by 24.5% and 35.4%, respectively, suggesting that at this time, the PS II of bagged tomato fruits had a higher light use efficiency, which provided energy foundation for the earlier ripening of the bagged fruits via further reducing the quantum yield of non-regulatory energy dissipation (Y(NO)).