Effects of high atmospheric CO₂ and heat stress on phytomass, yield and grain quality of winter wheat

Summary

Three winter wheat varieties were grown in growth chambers under controlled environmental conditions at two atmospheric CO₂ concentrations (375 and 750 μmol*mol⁻¹) with either an ambient temperature regime or with heat stress during grain filling (max 35°C, 8 hours a day for 15 days). Data on the aboveground biomass, tiller and ear number, yield components, harvest index, the protein content of the wholemeal and the functional parameters of the flour were determined after harvest. Mv Martina, a variety with very high yield potential, responded very positively to CO₂ treatment, exhibiting an increase in the tiller and ear number and in the number of grains per plant, resulting in 38 % higher yield without a deterioration in the grain quality. Neither CO₂ nor heat stress had a negative effect on the flour quality of this variety as the protein content and SDS sedimentation volumes increased in both treatments. Increased CO₂ had less influence on the yield of the other varieties, where the grain quality either decreased or remained at a similar level after CO₂ enrichment. Heat stress had a negative effect on TKW and grain yield, but this could be counterbalanced by elevated CO₂ level in two varieties. Elevated CO₂ and high temperature had opposite effects on the protein and gluten contents (except in Mv Martina), but the gluten index was lowest when both factors were present.