Table 2 Relative contents of the top 20 metabolites in rice grain hulls at different heading stages

Flavone C-glycosides

HoMoorientin

19.8 ± 0.21

20.1 ± 0.4

11.5 ± 0.28

5.29 ± 0.21

Orientin

18.2 ± 1.29

20.1 ± 0.64

13.5 ± 0.61

7.1 ± 0.49

8-C-Hexosyl-apigenin O-feruloylhexoside

11.4 ± 0.37

18.3 ± 0.53

15.5 ± 1.03

8.64 ± 1.0

Apigenin-8-C-glucoside

17.7 ± 0.93

14.1 ± 0.77

–

–

Genistein 8-C-glucoside

27.9 ± 1.08

21.8 ± 2.1

–

–

Isovitexin

31.6 ± 1.19

24.3 ± 1.5

–

–

Swertiajaponin

–

–

–

4.06 ± 0.15

Flavonols

Rutin

–

13.8 ± 0.81

16.2 ± 1.15

3.91 ± 0.19

Isorhamnetin-3-O-rutinoside

–

17.1 ± 0.34

17.7 ± 1.49

5.21 ± 0.39

Bioquercetin

–

16.9 ± 1.55

20.6 ± 1.86

4.80 ± 0.37

Quercetin-O-feruloyl-Pentoside

–

30.9 ± 0.68

38.9 ± 1.44

11.5 ± 0.18

Flavones

Tricin O-saccharic acid

–

–

10.2 ± 1.03

5.89 ± 0.47

Diosmetin-6-C-glucoside

–

–

10.1 ± 1.29

–

Tricin-O-Hexoside-O-rhamnoside

5.62 ± 0.73

–

12.0 ± 0.90

15.1 ± 0.45

Tricin 5-O-rutinoside

7.49 ± 0.59

12.9 ± 0.17

12.2 ± 0.59

9.02 ± 0.17

Salcolin B

14.6 ± 0.62

17.4 ± 1.23

12.9 ± 0.74

6.32 ± 0.26

Di-C,C-hexosyl-apigenin

17.3 ± 0.5

24.1 ± 1

22.4 ± 0.41

9.17 ± 0.34

Tricin 4'-O-(β-guaiacylglyceryl) ether 7-O-hexoside

27.6 ± 1.34

34.3 ± 2.03

29.9 ± 1.06

13.9 ± 0.74

Tricin O-malonylhexoside

38.2 ± 0.79

53.5 ± 1.81

39.2 ± 1.62

13.5 ± 0.39

Salcolin A

47.7 ± 1.09

51.2 ± 1.77

43.3 ± 1.41

27.6 ± 0.74

Tricin 4'-O-β-guaiacylglycerol

53.4 ± 0.64

60.7 ± 3.17

49.4 ± 0.87

28.5 ± 0.41

Tricin

12.4 ± 0.37

12.0 ± 0.95

–

4.83 ± 0.5

Tricin 4'-O-syringyl alcohol

9.92 ± 0.56

–

–

3.96 ± 0.12

Anthocyanins

Jaceosidin

6.67 ± 0.29

–

–

–

Cyanidin O-syringic acid

9.40 ± 0.26

66.2 ± 5.57

68.0 ± 2.72

3.85 ± 0.39

Cyanidin 3-rutinoside

7.11 ± 0.28

52.0 ± 1.40

43.4 ± 2.07

–

Cyanidin 3-O-glucoside

–

–

8.47 ± 0.49

–

Flavanols

Gallic acid O-feruloyl-O-hexosyl-O-hexoside

7.59 ± 0.75

–

–

–