[Dissipation mechanism of excessive energy in umbilical orange under phosphorus deficiency and strong light stress].

The dissipation mechanism of excessive energy of umbilical orange under phosphorus deficiency and strong light stress was studied with solution culture method. The results showed that under phosphorus deficiency and strong light stress, the photosynthetic pigment content, net photosynthetic rate (Pn), photorespiration rate (Pr), maximum fluorescence (Fm), photochemical efficiency (Fv/Fm) and electron transmit rate (ETR) of umbilical orange were all declined, while original fluorescence (Fo) and Pr/Pn ratio were raised. The fast-phase (qNf) of non-photochemical quenching of chlorophyll fluorescence was decreased, while the middle-phase (qNm) and slow-phase (qNs) were increased. After treated with DTT, Fo turned higher, but qNm and qNs were much lower than the control (H2O), while qNf did not have any significant change. Phosphorus deficiency and strong light stress aggravated photoinhibition of photosynthesis, which in turn started up several dissipation mechanisms in umbilical orange leaf.