Zinc Affects Differently Growth, Photosynthesis, Antioxidant Enzyme Activities and Phytochelatin Synthase Expression of Four Marine Diatoms

Table 2

Parameters (𝛼^𝐵, light utilization coefficient; 𝑃^{𝐵𝑚𝑎𝑥}, maximum gross photosynthesis; 𝐸_𝑘, irradiance for the light saturation of photosynthesis) of gross photosynthesis versus irradiance curves. 𝛼^𝐵: μmol 𝑂₂ mg⁻¹ Chl a  ℎ⁻¹ (μmol photons m⁻² s⁻¹)⁻¹; 𝑃^{𝐵𝑚𝑎𝑥}: μmol O₂ mg⁻¹ Chl a  ℎ⁻¹; 𝐸_𝑘: μmol photons m⁻² s⁻¹. Parameters (𝛼_{𝑟𝐸𝑇𝑅}, light utilization coefficient; 𝑟𝐸𝑇𝑅_𝑚𝑎𝑥, maximum relative electron transport rate; 𝐸_{𝑘𝑟𝐸𝑇𝑅}, irradiance for the light saturation of photosynthesis) of relative electron transport rate versus irradiance curves. 𝛼_{𝑟𝐸𝑇𝑅}/rETR (μmol photons m⁻² s⁻¹)⁻¹; 𝑟𝐸𝑇𝑅_𝑚𝑎𝑥: relative units; 𝐸_{𝑘𝑟𝐸𝑇𝑅}: μmol photons m⁻² s⁻¹.

Species	A. acutiuscula		A. coffeaeformis		N. palea		E. paludosa
	Control	Zn 20 μM	Control	Zn 20 μM	Control	Zn 20 μM	Control	Zn 20 μM
α ^B	2.23 ± 0.68^a	3.27 ± 0.31^b	2.31 ± 0.05^a	3.87 ± 0.20^b	3.71 ± 0.36^a	4.64 ± 0.75^a	3.01 ± 0.14^a	2.24 ± 0.13^b
𝑃^𝐵max	146 ± 11^a	177 ± 3^b	407 ± 44^a	580 ± 33^b	545 ± 27^a	438 ± 5^b	335 ± 2^a	259 ± 6^b
𝐸𝑘	88 ± 29^a	55 ± 4^a	175 ± 15^a	178 ± 18^a	153 ± 21^a	102 ± 16^a	110 ± 5^a	116 ± 4^a
𝛼rETR	0.21 ± 0.02^a	0.41 ± 0.03^b	0.36 ± 0.03^a	0.36 ± 0.01^a	0.42 ± 0.02^a	0.39 ± 0.03^a	0.48 ± 0.05^a	0.29 ±  0.01^b
rETRmax	37 ± 1^a	24 ± 1^b	36 ± 1^a	49 ± 2^b	95 ± 7^a	62 ± 3^b	43 ± 3^a	53 ± 3^b
𝐸𝑘rETR	187 ± 28^a	62 ± 7^b	112 ± 9^a	139 ± 8^a	224 ± 7^a	166 ± 19^b	90 ± 6^a	181 ± 8^c

Meanvalues±SE (n = 3–5). Significant different data are indicated with different superscripted letters (Tukey Test, 𝑃≤0.05).