Table 4.

F-test and means test for initial fluorescence (Fo) (µmol (photons) m⁻² s⁻¹), maximum fluorescence (Fm) (µmol (photons) m⁻² s⁻¹), variable fluorescence (Fv) (µmol (photons) m⁻² s⁻¹), the maximum quantum efficiency of photosystem II (Fv/Fm), the quantum efficiency of photosystem II (Y(II)), electron transport rate (ETR) (µmol (photons) m⁻² s⁻¹), minimum fluorescence of the illuminated plant tissue (Fo’) (µmol (photons) m⁻² s⁻¹), photochemical quenching coefficient (qL), the quantum yield of regulated photochemical quenching (Y(NPQ)), and the quantum yield of non-regulated photochemical quenching (Y(NO)) of traditional varieties of cowpea subjected to salinity levels of irrigation water.

F-Test (p-Value)
Sources of Variation	Fo	Fm	Fv	Fv/Fm	Y(II)
Block	0.000	0.000	0.000	0.442	0.445
Salinity	0.037	0.235	0.046	0.003	0.010
Varieties	0.314	0.485	0.475	0.313	0.881
Salinity × Varieties	0.616	0.963	0.983	0.668	0.222
Means comparison test (Standard Deviation, n = 75)
Salinity (dS m−1)	Fo	Fm	Fv	Fv/Fm	Y(II)
0.5	777.94 ± 11.21 A	3128.91 ± 35.94 A	2351.0 ± 33.99 B	0.75 ± 0.004 B	0.68 ± 0.008 A
4.5	749.48 ± 9.16 B	3178.00 ± 31.37 A	2428.5 ± 26.05 A	0.76 ± 0.002 A	0.65 ± 0.011 B
F-test (p-value)
Sources of Variation	ETR 1	Fo’ 1	qL 1	Y(NPQ) 1	Y(NO) 1
Block	0.000	0.2068	0.110	0.397	0.378
Salinity	0.000	0.9214	0.140	0.005	0.736
Varieties	0.308	0.5083	0.840	0.812	0.833
Salinity × Varieties	0.635	0.3448	0.626	0.203	0.393
Means comparison test (Standard Deviation, n = 75)
Salinity (dS m−1)	ETR	Fo’	qL	Y(NPQ)	Y(NO)
0.5	29.66 ± 2.47 B	2.85 ± 0.102 A	0.014 ± 0.0005 A	0.27 ± 0.007 B	0.05 ± 0.0010 A
4.5	53.10 ± 4.07 A	2.82 ± 0.082 A	0.013 ± 0.0005 A	0.30 ± 0.010 A	0.05 ± 0.0012 A

¹ Data transformed to square root. Equal uppercase letters in columns do not differ by Student’s t-test at a 5% probability level.