Table 2.

Pearson product moment correlation (correlation coefficient and its significance—r^P) between the studied morphological and photophysiological parameters of Potamogeton perfoliatus plants and their position (depth), light intensity (I) and red far-red ratio (r/fr) of the studied leaves within the water column in Lake Balaton.

	depth		r/fr		I
	r	P	r	P	r	P
α	− 0.669		0.577		0.562
ETRmax	− 0.824	**	0.810	**	0.803	**
Ik	− 0.743	*	0.744	*	0.732	*
Fv/Fm	0.766	*	− 0.879	**	− 0.905	**
qN	− 0.907	***	0.909	***	0.909	***
qP	− 0.905	***	0.893	**	0.883	**
length	0.559		− 0.729	*	− 0.755	*
width	− 0.348		0.287		0.292
LA	0.217		− 0.363		− 0.375
perimeter	0.393		− 0.585		− 0.615
circularity	− 0.433		0.626		0.674	*
total chl	0.581		− 0.740	*	− 0.780	*
chla/chlb	0.558		− 0.722	*	− 0.763	*
chl/car	0.596		− 0.751	*	− 0.789	*

The shown parameters are the maximum quantum yield for whole-chain electron transport (α), maximum electron transport capacity (ETR_max), the theoretical saturation light intensity (I_k), maximum quantum efficiency of PSII (F_v/F_m), non-photochemical quenching (qN), photochemical quenching (qP), length, width, leaf area (LA), perimeter and circularity of leaves, total chlorophyll (total chl), chlorophyll a to b ration (chl_a/chl_b), total chlorophyll to carotenoid ratio (chl/car). The significance of the correlations: *P < 0.05, **P < 0.01, ***P < 0.001.