Table 1.

Photosynthesis (in μmol CO₂ m⁻²·s⁻¹) of upper leaves of three cultivars of quinoa grown at ambient (400 μmol·mol⁻¹) or elevated (600 μmol·mol⁻¹) CO₂ concentrations, with or without a high temperature stress treatment during anthesis. Photosynthesis was measured at the growth PPFD of 1000 μmol·m⁻²·s⁻¹, and at the current daytime growth temperature (20 °C before and after the stress, and 35 °C during the stress). Photosynthesis was measured at the growth CO₂, ambient or elevated, and ambient plants were also measured at elevated CO₂ (ambient at elevated). Numbers followed by the same letters within a growth stage were not significantly different at p = 0.05.

Growth Stage	Cultivar	Ambient	Elevated	Ambient at Elevated
Before stress	Cherry Vanilla	38.8a	42.6b	44.2b
	Red Head	39.5a	42.5b	45.0b
	Salcedo	37.8a	43.6b	42.0b
During stress	Cherry Vanilla	32.7a	39.8b	40.8b
Stressed plants	Red Head	34.1a	41.6b	41.7b
	Salcedo	32.2a	37.8b	38.9b
After stress	Cherry Vanilla	35.2a	34.2a	40.3b
Stressed plants	Red Head	36.3a	37.1a	41.1b
	Salcedo	34.1a	35.0a	39.6b
After stress	Cherry Vanilla	34.7a	35.4a	40.8b
Control plants	Red Head	35.8a	36.2a	41.0b
	Salcedo	35.1a	35.8a	39.3b