PHOTOSYNTHESIS AND GROWTH OF WHEAT, RYE AND TRITICALE AT VARIOUS DAYLENGTHS AND NIGHT TEMPERATURES

Wheat, rye and Triticale were cultivated in a growth chamber in a liqu id nutrient solution, under light-dark periods 12/12 h or 16/8 h and u nder light/dark temperatures of 20/15-degrees-C for 20/8-degrees-C. Th e photosynthetic photon flux density limiting the net photosynthetic r ate was applied. In all the cereals investigated, during the initial 3 3-day period of their growth, a lack of positive relationship was note d between net photosynthesis rate and relative growth rate (RGR) of pl ants. However, very close positive correlation was found between the t otal daily net amount of CO2 assimilated and absolute growth rate (AGR ) of plants. Net photosynthetic rate was found to be increased by shor tening of the light period and it was decreased by lowering the temper ature in the dark.