Effect of water stress on primary photosynthetic process: interaction with light and temperature

Effect of water stress alone and in combination with light and temperature on chlorophyll fluorescence and photosynthetic electron transport have been studied in drought-resistant wheat. It was observed that water stress alone-did not modify the amplitude of variable fluorescence in leaf but showed slight decrease in photosynthetic electron transport. However, interaction with light caused significant decrease in the efficiency of photosynthesis. This was greater when photoinhibited at 30 degrees C than at 10 degrees C. Results suggest that water stress alone does not lead to significant damage to the primary photochemistry but photoinhibition causes both inhibition of electron transport activity and chlorophyll fluorescence. The damage was further enhanced by the combination of water stress and high temperature.