关键词: 玉米低温冷害, 玉米低温冷害, 决策支持系统, 远程诊断, 网络管理, J2EE

Abstract:

Exposure of potted oil palm seedlings to different temperature(25℃,10℃,7℃,4℃and 1℃) under low light(30μmol/)for 3 day respectively, the photosynthesis and chlorophyll fluorescence parameters were measured in leaves of oil palm seedlings. The results showed that when the treatment temperature decreased from 25 ℃ to 4 ℃,the net photosynthetic rate(Pn),the stomata conductance(Gs), the transpiration rate(Tr)，the intercellular CO2 concentration(Ci) all decreased evidently,but stomatal limitation(Ls) and water use efficiency (WUE) increased significantly, It is suggested that stomatal limitation became the mainly cause of the reduction of Pn in oil palm seedlings. However, as the temperature dropped from 4 ℃ to 1 ℃, the Pn,Gs,Tr,WUE, Ls were decreased significantly,whereas the Ci was increased dramatically, It indicated that the photosynthesis inhibition by severe low temperature stress was resulted from non-stomatal limitations. The determination of chlorophyll fluorescence parameters revealed that as the temperature dropped continuously,the initial fluorescence (Fo) increased gradually,the PSⅡmaximal photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP), nonphotochemical quenching coefficient (qN) decreased continuously,these parameters had a change dramatically below 4℃. It indicated that exposure of oil palm seedlings to extreme low temperature,the photoinhibition in oil palm seedlings leaves has been induced significantly, the excess excitation energy didn’t dissipated by thermal dissipation route,and accumulated largely in the reaction center of PSⅡ,so that caused damage severely to photosynthesis apparatus and the final weakened quickly photosynthesis capacity of oil palm seedlings.