2018 ASHS Annual Conference

The aim of this study was to develop the photosynthetic models of Kimchi cabbages under the abnormal temperatures at the different growth stages for evaluation of the net photosynthetic rate. The Kimchi cabbage plants were applied to the extreme high temperatures (25/22, 30/27, 35/31^oC; photo-/dark periods) at 7 to 10 days after transplanting (DAT) and 40 to 43 DAT using the extreme weather simulators. Except for these periods, the environments in terms of air temperature, relative humidity, radiation, and precipitation were set by the previous meteorological data (mean of September to November 2014-2016, Haenam, Republic of Korea). The photosynthetic CO₂ response curves (An-Ci) were measured at 16, 29, 43, 59, and 70 DAT using a portable gas exchange system. An-Ci data were used to calculate three biochemical parameters in terms of photochemical efficiency, carboxylation conductance, and dark respiration at each measuring date. Those were used to develop the photosynthetic models, modified Thornley’s model, representing the prediction of net photosynthetic rate by CO₂ concentration and growth stages. The simulated net photosynthetic rates (s-An) differed as affected by extreme weather events, the s-An with extreme high temperature treatment (35/31^oC) was 19.7 µmol m^-2 s^-1 which was evaluated approximately 3% deduction compared with control. Results indicated that developed photosynthetic models might be applied to evaluate retard growth and the net photosynthetic rate under abnormal temperature conditions.