Table 1.

Concentrations of NO₃⁻ and HTGs in leaf tissue under different stress conditions

	Concentration of nitrate, mg/g d.w.		Concentration of HTG [1]*, μg/g d.w.		Concentration of HTG [2]*, μg/g d.w.
No days of treatment	4	7	4	7	4	7
Full nutrient supplied	49.6 ± 4.8	36.1 ± 1.5	n.d.	n.d.	n.d	n.d
Total nutrient deprived	15.8 ± 1.0	3.6 ± 0.8	1155 ± 328	4729 ± 298	120 ± 61	1145 ± 298
Nitrate deprived	7.4 ± 2.4	0.2 ± 0.2	731 ± 240	2395 ± 366	383 ± 211	431 ± 152
Ammonium substituted	15.5 ± 4.4	2.7 ± 0.6	80 ± 41	2480 ± 218	n.d.	486 ± 56
Potassium deprived	32.6 ± 14.7	29.0 ± 1.9	44 ± 40	695 ± 170	n.d.	90 ± 57
Salt stress	36.3 ± 3.8	27.9 ± 2.4	n.d.	n.d.	n.d.	n.d.
Oxidative stress	41.2 ± 6.2	12.9 ± 1.7	170 ± 75	2583 ± 518	21 ± 20	571 ± 137
Osmotic stress	61.6 ± 4.0	72.3 ± 10.4	n.d.	n.d.	n.d.	n.d.
Root damage	23.0 ± 4.9	14.5 ± 2.7	119 ± 76	1920 ± 21	23 ± 21	529 ± 220
Leaf damage	39.1 ± 1.9	47.5 ± 11.5	n.d.	n.d.	n.d.	n.d.
Cold treatment	49.9 ± 11.6	21.8 ± 5.8	0.25 ± 0.25	n.d.	n.d.	n.d.

*Values represent average (± SD) of three biological and two technical replicates (n = 6); integration was achieved by summation of the NMR regions: δ5.725–5.685 [1] and δ5.635–5.585 [2]. Where HTG concentration was <100 μg/g, values stated are considered to be less accurate and are given as indications of the presence of a small peak. However, in all cases the presence of the HTG was confirmed by the presence of the relevant methyl group singlet in NMR and the 287/303 ions in positive ion ESI. n.d., not detected.