Abstract: In this study,cucumber leaves were under high temperature and strong light stress after two days of spraying with 50～400 μmol·L^-1 salicylic acid (SA) solution.The measurements showed that SA pretreatment could inhibit the decrease of intrinsic photochemical efficiency (F_v/F_m),quantum yield of PSII(ΦPSⅡ),maximum fluorescence value(F_m),and photochemical quenching (qP) by 16.1%～30.2%,11.9%～33.0%,7.2%～41.0% and 27.2%～160.8%,respectively,and promote the increase of non-photochemical quenching (NPQ) by 13.1%～62.9%,but had little effect on initial fluorescence value (F_o).SA pretreatment could also inhibit the decrease of xanthophyll cycle pool in cucumber leaves,and increase the deepoxidation extent of xanthophyll cycle (A+Z)/(V+A+Z),which was 29.5% and 24.6% higher than control,respectively.It was suggested that SA could protect the photosynthetic apparatus of cucumber leaves under high temperature and strong light through promoting non-radiative energy dissipation.

Key words: Immobilization, Degradation, Phenanthrene, Pyrene Soil