Analysis of variance of the fixed effects.

Period (P), site (S) clone (C), hour (H), and their interactions, on the net CO2 assimilation rate (A), transpiration rate (E), stomatal conductance (gs), intercellular CO2 concentration (Ci), leaf temperature (LT), photochemical efficiency of PSII (ΦPSII), electron transport rate (ETR), maximum photochemical efficiency of PSII (Fv/Fm), efficiency of excitation energy captured by open PSII reaction centers (Fv'/Fm'), photochemical quenching coefficient (qP), and non-photochemical quenching (NPQ).