Responses of winter wheat (Triticum aestivum L.) varieties to drought stress and elevated CO2 levels: a comparative analysis of growth, spike characteristics, and grain yield

Abstract The study highlights the impact of drought stress at different phenological stages and different carbon dioxide concentrations on the growth and productivity of four Hungarian winter wheat varieties (‘Mv Ikva’, ‘Mv Nádor’, ‘Mv Nemere’, ‘Mv Kolompos’). The experiments were performed at the HUN-REN Centre for Agricultural Research and the experimental setting contained three different watering regimes (optimal watering as control, water withdrawal at the stem elongation, water withdrawal at the heading developmental stage as drought treatment) and three different carbon dioxide levels (current atmospheric, 700 ppm or 1000 ppm). Our findings contribute to a better understanding of how atmospheric conditions, including elevated CO 2 levels, might interact with drought stress to influence wheat growth. At current atmospheric CO 2 concentration drought experienced during the early developmental stage caused a significant reduction in several measured parameters compared to drought occurring at the heading stage. At elevated CO 2 levels (700 ppm and 1000 ppm), the drought-induced reductions in plant height were generally less severe. Drought stress during stem elongation significantly reduced spike weights, at 700 ppm CO 2 concentration, the early-stage drought had a stronger negative impact on this parameter than the late-stage drought. Early drought significantly reduced the grain number in the main spikes under ambient CO 2 levels, while heading-stage drought primarily affected the secondary spikes.