关键词: 甘蓝, 高温强光, 光合速率, ΦPSII, NPQ

Abstract: Two types of cabbage cultivars ( heat-sensitive and heat-tolerant) were used asmaterial to study the difference of photosynthesis under short-term high temperature stress with high light. Results showed that photosynthetic rate of‘Daniuxin’was app roximately 30% higher than that of‘Wufen 8’under 1200 mol·m^{- 2} ·s^{- 1} PFD when leaf temperature was 40℃. Compared with at 28℃, their photosynthetic rates decreased 7% and 24%, respectively. Under 40℃, the quantum yield of PSII electron transport (ΦPSII) and maximal
photochemical efficiency of PSII in the light ( Fvp/Fmp) decreased with the increase of light, but non-photochemical quenching (NPQ) increased continuously, its slow-component ( q I) remained app roximately 10% of
NPQ, the increase of fast component ( qf) is the main factor leading to the increase of NPQ, indicating that xanthophyll cycle2dependent‘high energy’quenching was the main mechanism for effectively dissipating the excess excitation energy. However, there were no significant differences inΦPSII, Fv'/Fm', NPQ, qf, qI between two types of cabbage cultivars. In addition, no significant difference was observed in maximal photochemical efficiency of PSII (Fv/Fm) , intercellular CO2 concentration (Ci) , photoresp iratory rate (Pr). Therefore,the difference of photosynthetic rates between two cultivars under short-term high temperature stresswith the high lightmight result from non-stomatal limitation which had no relation with photoreaction process.

Key words: Brassica oleracea L. var. capitata L., High temperature and high light, Net photosynthetic rate, ΦPSII, NPQ