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 liquid nutrient solution, under light-dark periods 12/12 h or 16/8 h and under light/dark temperatures of 20/15-degrees-C for 20/8-degrees-C. The photosynthetic photon flux density limiting the net photosynthetic rate was applied. In all the cereals investigated, during the initial 33-day period of their growth, a lack of positive relationship was noted between net photosynthesis rate and relative growth rate (RGR) of plants. However, very close positive correlation was found between the total daily net amount of CO2 assimilated and absolute growth rate (AGR) of plants. Net photosynthetic rate was found to be increased by shortening of the light period and it was decreased by lowering the temperature in the dark.