Table 4.

Correlations of SPAD, LAI, Chl with PNA and LNA at different growth stages in experiments 1, 2, and 4.

Experiment No.	Growth stage	Nitrogen accumulation	SPAD		LAI		Chl
			Regression model	R2	Regression model	R2	Regression model	R2
Experiment 1 2007	TI	PNA	E	0.68*	L	0.69*	L	0.90***
		LNA	P	0.69	P	0.71*	L	0.90***
	SE	PNA	L	0.73**	Q	0.77**	L	0.92***
		LNA	Q	0.74**	L	0.76**	L	0.91***
	PI	PNA	Q	0.74**	E	0.79**	L	0.97***
		LNA	L	0.68*	P	0.76**	L	0.97***
	BT	PNA	P	0.71**	Q	0.76**	L	0.99***
		LNA	L	0.73*	Q	0.73**	L	0.99***
	HD	PNA	Q	0.72**	L	0.71*	L	0.95***
		LNA	Q	0.75*	L	0.76**	L	0.96***
	Entire stages	PNA	–	–	–	–	L	0.94***
		LNA	–	–	–	–	L	0.92***
Experiment 2 2008	TI	PNA	L	0.61*	P	–	L	0.86***
		LNA	L	0.59*	L	–	L	0.83***
	SE	PNA	E	0.69**	L	0.76**	L	0.82***
		LNA	E	0.67*	P	0.84**	L	0.85***
	PI	PNA	L	0.70**	L	0.76**	L	0.95**
		LNA	P	0.71**	L	0.81**	L	0.92***
	BT	PNA	Q	0.80**	E	0.79**	L	0.95***
		LNA	L	0.73**	Q	0.81**	L	0.97***
	HD	PNA	E	0.79**	Q	0.64*	L	0.98***
		LNA	P	0.77**	L	0.79**	L	0.94***
	Entire stages	PNA	–	–	–	–	L	0.97***
		LNA	–	–	–	–	L	0.98***
Experiment 4 2013	TI	PNA	Q	0.84**	L	0.56*	L	0.89**
		LNA	Q	0.84**	L	0.52*	L	0.90**
	SE	PNA	L	0.51*	E	0.73*	L	0.94***
		LNA	L	0.53*	E	0.79**	L	0.93***
	PI	PNA	P	0.72**	L	0.74*	L	0.97***
		LNA	L	0.68**	P	0.86**	L	0.94***
	BT	PNA	L	0.72*	Q	0.78	L	0.92***
		LNA	E	0.74**	L	0.67*	L	0.91***
	HD	PNA	Q	0.86**	E	0.83**	L	0.95***
		LNA	Q	0.79**	P	0.71*	L	0.96***
	FL	PNA	L	0.68*	L	0.13ns	L	0.97***
		LNA	E	0.63*	E	0.2ns	L	0.98***
	Entire stages	PNA	–	–	–	–	L	0.92***
		LNA	–	–	–	–	L	0.88***

Regression models: linear (L), quadratic (Q), exponential (E), power (P);

ns and “–” means non-significance;

^*F-test statistical significance at 0.05 probability level;

^**F-test statistical significance at 0.01 probability level;

^***F-test statistical significance at 0.001 probability level.