Photosynthesis and Rubisco kinetics in spring wheat and meadow fescue under conditions of simulated climate change with elevated CO2 and increased temperatures

Abstract

Spring wheat (Triticum aestivum L.cv.Polkka)and meadow fescue (Festuca pratensis Hudson cv. Kalevi)cwere grown in ambient and elevated (700 µl l -1 )carbon dioxide concentration both at present ambient temperatures and at temperatures 3°C higher than at present simulating a future climate.The CO2 concentrations were elevated in large (3 m in diameter)open top chambers and the temperatures in a greenhouse built over the experimental field.The photosynthetic rate of both wheat and meadow fescue was 31 –37%higher in elevated carbon dioxide (eCO2 )than in ambient CO 2 (aCO2 )throughout the growing season.The enhancement in wheat photosynthesis in eCO2 declined 10 –13 days before yellow ripeness,at which point the rate of photosynthesis in both CO 2 treatments declined.The stomatal conductance of wheat and meadow fescue was 23–36% lower in eCO2 than in aCO2 .The amount and activity of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) in wheat were lower under conditions of eCO2 ,except at elevated temperatures in 1993 when there was a clear yield increase.There was no clear change in the amount and activity of Rubisco in meadow fescue under eCO2 at either elevated or ambient temperature.This suggests that adaptation to elevated CO2 at biochemical level occurs only when there is insufficient sink for photosynthetic products.While the sink size of wheat can be increased only by introducing new,more productive genotypes,the sink size of meadow fescue can be regulated by fitting the cutting schedule to growth.;

A comparative ideotype, yield component and cultivation value analysis for spring wheat adaptation in Finland

“…With datasets IV and V, crop physiological experiments and simulation studies were used to evaluate the effects of elevated atmospheric CO 2 and elevated temperature levels on yield potential and phenological development of HiL and MidE spring wheat genotypes. The SILMU I (The Finnish Research Program for Climate Change, 1992Change, −1994 data was extracted from Open Top Chamber experiments (Hakala 1998, Hakala et al 1999, Laurila 2001. The SIL-MU II data was extracted from greenhouse and pot experiments (Saarikko et al 1996, Saarikko 1999.…”

Increase in perennial forage yields driven by climate change, at Apukka Research Station, Rovaniemi, 1980-2017

“…Even though the longer growing season and milder winters will probably have the greatest effect on the grass growth in the north, increases in the ambient CO 2 concentrations may also have a positive effect. An about 300 ppm increase (from 360 to about 700 ppm) in atmospheric CO 2 concentration increased the rate of photosynthesis of meadow fescue (Festuca pratensis) by 30-40 % in open top chamber experiments in Jokioinen, Finland in 1992Finland in -1995 (Hakala et al 1999). This resulted in an about 10% increase in biomass in ambient temperatures Manuscript received September 2019 140 and 20-30 % increase in biomass, when temperatures were also increased and the cutting regime was adjusted to the growth potential to avoid canopy closure (Hakala and Mela 1996).…”