Table 2.

Effects of nitrogen application on gas exchange parameters of tomato leaves under high-temperature stress.

Treatment	P Nmax (μmol m-2s-1)	g s (mol m-2 s-1)	C i (μmol mol-1)	Ls	WUE (μmol mmol-1)
CKN1	6.34 ± 0.07 k	0.04 ± 0.01 i	363.82 ± 1.82 a	0.09 ± 0.01 d	1.11 ± 0.13 hi
CKN2	8.62 ± 0.13 h	0.08 ± 0.01 i	358.63 ± 1.19 b	0.10 ± 0.01 d	1.42 ± 0.05 gh
CKN3	14.54 ± 0.08 d	0.33 ± 0.05 ef	329.78 ± 2.48 d	0.18 ± 0.03 bc	2.56 ± 0.17 d
CKN4	17.82 ± 0.26 b	0.49 ± 0.04 bc	307.01 ± 2.79 g	0.23 ± 0.03 a	3.94 ± 0.11 b
CKN5	7.89 ± 0.14 i	0.06 ± 0.01 i	360.83 ± 2.42 ab	0.10 ± 0.03 d	1.49 ± 0.12 g
SHTN1	10.30 ± 0.12 g	0.22 ± 0.05 h	335.29 ± 1.86 c	0.16 ± 0.01 c	1.83 ± 0.14 f
SHTN2	14.65 ± 0.39 d	0.37 ± 0.04 de	325.71 ± 1.59 e	0.19 ± 0.01 abc	2.68 ± 0.18 d
SHTN3	20.59 ± 0.27 a	0.60 ± 0.05 a	307.37 ± 1.14 g	0.23 ± 0.01 a	4.49 ± 0.24 a
SHTN4	18.00 ± 0.09 b	0.50 ± 0.02 b	309.26 ± 1.81 g	0.23 ± 0.02 a	3.90 ± 0.03 b
SHTN5	16.03 ± 0.17 c	0.43 ± 0.02 cd	317.60 ± 1.45 f	0.21 ± 0.02 ab	3.23 ± 0.09 c
HTN1	6.11 ± 0.12 k	0.04 ± 0.01 i	363.08 ± 3.22 a	0.09 ± 0.01 d	1.15 ± 0.15 hi
HTN2	14.69 ± 0.20 d	0.38 ± 0.05 de	323.68 ± 2.53 e	0.19 ± 0.02 abc	2.64 ± 0.11 d
HTN3	12.74 ± 0.05 e	0.30 ± 0.01 fg	330.49 ± 0.98 d	0.17 ± 0.01 bc	2.26 ± 0.12 e
HTN4	10.85 ± 0.12 f	0.24 ± 0.01 gh	332.86 ± 1.28 cd	0.17 ± 0.02 bc	1.92 ± 0.07 f
HTN5	7.03 ± 0.11 j	0.05 ± 0.01 i	361.66 ± 1.57 ab	0.10 ± 0.01 d	1.20 ± 0.09 hi
Temperature (T)	**	**	**	**	**
Nitrogen (N)	**	**	**	**	**
T x N	**	**	**	**	**

Different lowercase letters indicate significant differences among treatments at the P< 0.05 level by Duncan’s test. CK, SHT and HT are the control, sub-high temperature and high temperature treatment, respectively. Values are mean ± SD (n = 3). ** indicates significance at P ≤ 0.01.