Table 5.

Net photosynthesis (μmol CO₂ m⁻² s⁻¹), stomatal conductance (mmol CO₂ m⁻² s⁻¹), intercellular CO₂ concentration (μmol CO₂ mol⁻¹), quantum yield efficiency of PSII, Rubisco activity (μmol CO₂ mg⁻¹protein min⁻¹), photosynthetic nitrogen use efficiency (P-NUE; g m⁻²) and plant dry mass (g plant⁻¹) in mustard (Brassica juncea L.) cv Pusa Jai Kisan at 30 DAS. Plants were treated either with 5 mM N, 10 mM N, 200 µl l⁻¹ ethephon in different combinations and grown with or without 100 mM NaCl. Data means with the same letter are not different significantly at P < 0.05. DW, dry weight; FW, fresh weight.

Treatments	Net photosynthesis	Stomatal conductance	Intercellular CO2 concentration	Quantum yield efficiency of PS II	Rubisco activity	P-NUE	Plant dry mass
Control	13.4 ± 0.81ef	268 ± 16.4f	182 ± 9.3f	0.70 ± 0.03e	0.99 ± 0.04f	31 ± 1.58f	0.83 ± 0.087f
5 mM N (N5)	14.1 ± 0.9e	296 ± 20.3e	204 ± 10.8e	0.729 ± 0.03e	1.10 ± 0.06e	36 ± 2.4e	0.90 ± 0.089e
10 mM N (N10)	18.0 ± 1.27c	351 ± 23.1c	263 ± 13.6c	0.838 ± 0.04c	1.33 ± 0.08c	56 ± 3.6c	1.5 ± 0.10c
100 mM NaCl	8.3 ± 0.41h	202 ± 11.8h	131 ± 6.6h	0.602 ± 0.02 g	0.47 ± 0.02h	16 ± 1.3h	0.6 ± 0.059h
200 µl l−1 ethephon (E)	16.2 ± 1.15d	326 ± 22.3d	224 ± 12.2d	0.763 ± 0.04d	1.22 ± 0.07d	45 ± 3.1d	1.2 ± 0.098d
N5 + NaCl	9.5 ± 0.52 g	216 ± 16.9 g	153 ± 7.5 g	0.659 ± 0.03f	0.63 ± 0.04 g	23 ± 1.5 g	0.7 ± 0.068 g
N10 + NaCl	12.9 ± 0.7f	273 ± 17.7f	175 ± 9.2f	0.694 ± 0.04e	1.0 ± 0.05f	32 ± 1.62f	0.81 ± 0.08f
NaCl + E	13.2 ± 0.96f	286 ± 18.4f	187 ± 10.1f	0.719 ± 0.03de	1.03 ± 0.04f	30 ± 1.44f	0.87 ± 0.082f
N5 + E	21.3 ± 1.4b	410 ± 30.4b	303 ± 16.8b	0.899 ± 0.05b	1.59 ± 0.14b	63 ± 3.8b	1.9 ± 0.15b
N10 + E	23.4 ± 1.56a	447 ± 342a	327 ± 17.9a	0.947 ± 0.07a	1.79 ± 0.17a	69 ± 4.1a	2.2 ± 0.17a
N5 + NaCl + E	15.0 ± 1.09e	315 ± 21.1e	212 ± 11.1e	0.736 ± 0.04d	1.18 ± 0.06e	38 ± 2.2e	0.99 ± 0.092e
N10 + NaCl + E	18.6 ± 1.29c	364 ± 25.3bc	264 ± 15.6c	0.844 ± 0.05c	1.44 ± 0.08c	59 ± 3.4c	1.4 ± 0.096c