Plant material and photosynthesis
Sunflower (Helianthus annuus L.) var. XRQ was sown directly in
sand (washed with distilled water) in the greenhouse, using 7-L pots.
Growth conditions were: 12/12 h photoperiod, 25/18°C air temperature,
70/60% relative humidity day/night. Photosynthetic parameters were
measured using a portable open system Li-Cor 6400 XT. Net assimilation
(A ) and conductance reported in Fig. 2 was obtained under
saturating light (1500 µmol m-2 s-1PAR) at 400 µmol mol-1 CO2 and 21%
O2. Night respiration (R n) was
measured after photosynthesis measurements on dark-adapted leaves (30
min) at 400 µmol mol-1 CO2, 21%
O2 and 25°C.