The net photosynthetic rate (Pn), stomatal conductance (Gs),
and transpiration rate (Tr) were measured from the youngest
fully expanded leaves using a portable CIRAS-2 photosynthesis
system (PP-Systems, Hitchin, UK). The assimilatory chamber was
controlled to maintain the leaf temperature at 25 ◦C, CO2 concentration
at 360 mol mol−1, and photosynthetic photon-flux density
at 800 mol m−2 s−1. Six replicate plants per treatment were measured
between 09:00 and 12:00 h on sunny days.