Fig. 3

Chlorophyll fluorescence parameters of Welsh onions under different light conditions, including: a maximum photochemical efficiency of PSII under dark adaptation (Fv/Fm); b maximum photochemical efficiency of PSII under light adaptation (Fv’/Fm′); c photochemical quenching coefficient (qP); d actual photochemical efficiency (ΦPSII); e apparent electron transport rate (ETR); and f non-photochemical quenching coefficient (NPQ) = 1-(Fm′-Fo’)/(Fm-Fo). Values are means of 5 replicates ± SD. Different letters (a, b, c, d) in the same column indicate significant differences among treatments at P ≤ 0.05 according to Duncan’s new multiple range test. W: white light; B: blue light; G: green light; Y: yellow light; R: red light. n = 5