Abstract: Cut flower chrysanthemum (Dendranthema grandiflora ‘Jinba’) plants were treated with 40 ℃/35 ℃ or 33 ℃/28 ℃ (day/night) for 11 days and then transferred to 23 ℃/18 ℃ for 5 days to study the changes in their photosynthesis and fluorescence parameters under high temperature stress and normal temperature recovery. The results showed that on the 5^th day of 33 ℃/28 ℃ treatment, net photosynthesis (P_n) decreased gradually and stomatal conductance (G_s) decreased evidently; while after recovery for 5 days, both P_n and G_s resumed to 80% of the control. At 40 ℃/35 ℃,P_n and G_s decreased dramatically. The increase of intercellular CO₂ concentration (C_i) at the early stage under given high temperatures showed that the photosynthesis inhibition by high temperature stress was resulted from non-stomatal limitations. However, 9 days later, stomatal limitation became the mainly cause of photosynthesis inhibition. The intrinsic photochemical efficiency (F_v/F_m), quantum yield of PSⅡ(Φ_PSⅡ), and the efficiency of excitation energy capture by open PSⅡ reaction center（F_v′/F_m′） at 33 ℃/28 ℃ and 40 ℃/35 ℃ all decreased, with antenna heat dissipation increased, indicating that reaction center was protected by decreased light capture and efficiency of electron transfer through PSⅡ. The photochemical quenching (q_P) at 33 ℃/28 ℃ descended first and turned to rise then, suggesting that the electron transfer was firstly restrained by the stress. Contrastively, q_P rose continuously at 40 ℃/35 ℃, indicating that oxygen-evolving complex (OEC) was the location in chrysanthemum photosynthesis apparatus most sensitive to extreme high tempe rature.

Key words: soil available phosphorus, biochar, meta analysis, soil phosphatase, plant phosphorus concentration