FEEDBACK INHIBITION OF PHOTOSYNTHESIS IN RICE MEASURED BY O2 DEPENDENT TRANSIENTS

摘要: The kinetic properties of photosynthesis (both transient and steady-state) were monitored using three non-invasive techniques to evaluate limitations on triose-phosphate (triose-P) conversion carbohydrate in rice. These included analyzing the O2 sensitivity CO2 fixation assimilatory charge (AC) gas exchange (estimate ribulose 1,5- bisphosphate pool) measuring Photosystem II activity by chlorophyll fluorescence analysis under varying light, temperature partial pressures. Photosynthesis was inhibited transiently upon switching from 20 2 kPa (reversed sensitivity), degree which correlated with a terminal, steady-state suppression low enhancement photosynthesis. Under current ambient levels moderate high pattern more obvious at 18 °C than 26 while 34 no tra nsient response observed. inhibition ranged 15% 31% depending pre-measurement temperature. This pattern, symptomatic feedback, observed increasing light pressures feedback decreasing (18 °C) up (34 °C). conditions, rate assimilation is shifted being photorespiration limited triose-P utilization limited. Transitory changes rates (A) indicative coincided transitory drop electron transport. In contrast previous studies many C3 species, our indicate that rice shows susceptibility temperatures atmospheric CO2.