Table 1.

The infrared absorption frequencies of the CW and tentative assignment. Seedlings of C. sinensis and C. grandis were treated with nutrient solution (Control, pH 4.3) or supplemented by 1.0 mM Al³⁺ (1.0 mM Al toxicity, pH 4.3). The lateral root CW samples were extracted for FTIR spectra analysis

Wavenumber (cm-1)				Tentative Assignment	Reference
C. sinensis		C. grandis
Control	Al toxicity	Control	Al toxicity
3400	3400	3400	3396	OH stretching	[27]
2924	2926	2924	2926	CH asymmetric stretching	[28]
2856	2858	2858	2860	CH symmetric stretching	[28]
1740	1740	1740	1740	C=O stretching of ester	[28]
1649	1649	1649	1649	C=O stretching of amide I band	[29]
1545	1543	1543	1543	NH bending and CN stretching of amide II band	[29]
1514	1518	1520	1520	NH bending and CN stretching of amide II band	[30]
1427	1427	1427	1427	CH2 symmetric deformation	[31]
1375	1375	1373	1373	COO- symmetric stretching and aliphatic group vibration	[32]
1329	1331	1327	1331	C-O	[33]
1246	1244	1246	1244	C=O stretching or NH bending of amide III bands	[32]
1155	1153	1153	1153	phosphoryl group	[28]
1103	1101	1103	1105	C=O stretching, alclhol hydroxyl, ether or ester base	[29]
1059	1047	1059	1054	C-OH stretching of alcoholic groups and carboxylic acids	[34]
899	-	899	906	β-linkage between two glucose units	[31]