Relation between photosynthesis and dark respiration in cereal leaves

From the light response curves of net photosynthesis at 30 degrees C, the values of dark respiration, apparent quantum yield and light compensation point were calculated for leaves of Triticum turgidum, Hordeum chilense (H1(1)H35 and H71 lines), and tritordeum HT31, an amphiploid from N. chilense and T. turgidum. Tritordeum HT31 has an unusually low light compensation point and dark respiration rate; at high irradiance, its rate of O-2 evolution was within the range of a typical sun plant. In the five genotypes, both the light compensation point and the apparent quantum yield were positively correlated with the dark respiration rate. T. turgidum and H. chilense H71 had a larger chlorophyll content than tritordeum HT31. Leaf chlorophyll content per unit fresh mass was correlated to dark respiration rate, apparent quantum yield and light compensation point. These results indicate that in leaves from cereals grown under identical environmental conditions, there is a close association between chlorophyll content, dark respiration rate and apparent quantum yield.