Changes in photosynthesis in inbred maize lines with different degrees of chilling tolerance grown at optimum and suboptimum temperatures

The effects of growth temperature on changes in net photosynthetic rate (PN) and the chlorophyll fluorescence induction parameter F-v/F-m were investigated after cold stress in inbred maize lines with different degrees of cold tolerance. There was no significant difference between lines grown at optimum temperatures of 25/23 and 20/18 degrees C as regards P-N and F-v/F-m determined at the growth temperature, but these parameters were lower for plants grown at a suboptimum temperature of 15/13 degrees C. After cold treatment, the decrease in P-N was more pronounced in chilling-sensitive lines. The higher the growth temperature was, the more pronounced decrease occurred in P-N and F-v/F-m. Thus at low growth temperature both damaging and adaptive processes occur.