The response of two secondary provenances of Jatropha curcas originated respectively from Hainan Province and Guizhou Province to heat stress treatments was investigated.The capacity of scavenging organic free radical of DPPH· in both secondary provenances firstly increased and then decreased with increasing temperature,and presented one peak pattern.The peak value was at 30 ℃ in Guizhou secondary provenance and at 35 ℃ in Hainan secondary provenance,respectively.Antioxidative ability in Hainan secondary provenance was significantly higher than that in Guizhou secondary provenance under high temperature treatment(>35 ℃).The maximal photosynthetic evolution of oxygen was at 40 ℃ in Hainan secondary provenance,whereas 35 ℃ in Guizhou secondary provenance.There was little change in the maximal primary photochemical quantum efficiency(F_v/F_m)of the PSⅡ,however the non-circle PSⅡquantum efficiency(Φ_PSⅡ)and the photochemical quenching(q_P)of Hainan were obvious higher than those of Guizhou secondary provenance.The nonphotochemical quenching(NPQ)of Hainan displayed more tolerance to high temperature than that of Guizhou secondary provenance.F_o-temperature curves showed that the inflexion temperature(T_i)of Hainan and Guizhou secondary provenance was 52 ℃ and 50 ℃ respectively.The experiment results indicated that Hainan secondary provenance of J.curcas was able to maintain relative higher function of photosynthetic apparatus because of its high antioxidative ability and more stability of membrane under high temperature condition.This would be one of possible reasons that Hainan secondary provenance displayed stronger resistance to high temperature than Guizhou secondary provenance.
