Changes in photosynthetic capacity of some tomato landraces during drought stress

In this study, in order to evaluate the effects of drought stress on photosynthetic capacity of 17 different landraces and two commercial tomato hybrids, plant irrigation was stopped at the seedling stage and the changes in photosynthetic capacity during seven days of water withholding was measured by OJIP test. The results showed that the relative maximal variable fluorescence (FM/F0), electron transport flux per reaction center (ET0/RC), maximum quantum efficiency of PSII (FV/FM or FP0) and performance index on the absorption basis (PIabs) were decreased in drought-induced plants. In these plants, specific energy fluxes per reaction center for energy absorption (ABS/RC), trapped energy flux per reaction center (TR0/RC) and dissipated energy flux per reaction center (DI0/RC) were increased. The values of decrease and increase in plants were different, indicating the difference in drought tolerance levels in plants. The results also showed that the more drought-tolerant plants had less difference in the values of the parameters compared to their control. The results of this study help us to find the differences between the responses of the parameters related to the health of the plants photosynthetic capacity and provide theoretical foundations for improving tomato tolerance to dry climatic conditions.