Table 2 Effects of supplementary lighting with different spectral compositions on tomato plant growth after 14 and 42 days. Data are presented as mean ± standard error (n = 3 biological replicates). Different letters indicate significant differences at P < 0.05.

Plant height/cm

14d

35.36 ± 1.38b

36.22 ± 1.20b

35.90 ± 0.06b

36.24 ± 2.09b

35.73 ± 0.79b

36.39 ± 2.12b

40.03 ± 1.41a

42d

163.67 ± 1.94c

174.42 ± 5.53ab

174.00 ± 3.61ab

176.33 ± 7.59ab

179.50 ± 3.54a

170.67 ± 4.78bc

177.33 ± 5.35ab

Stem diameter/mm

14d

8.45 ± 0.22b

9.24 ± 0.23a

9.02 ± 0.23a

9.23 ± 0.35a

9.09 ± 0.31a

9.01 ± 0.23a

9.10 ± 0.20a

42d

12.83 ± 0.34b

15.15 ± 0.36a

14.89 ± 0.16a

15.22 ± 0.60a

14.92 ± 0.34a

14.60 ± 0.71a

14.63 ± 0.18a

leaf count

14d

12.42 ± 0.38b

13.00 ± 0.50ab

12.67 ± 0.52ab

12.58 ± 0.58ab

12.42 ± 0.29b

12.83 ± 0.38ab

13.17 ± 0.14a

42d

25.25 ± 0.66 cd

26.25 ± 0.25a

26.00 ± 0.50ab

25.58 ± 0.14abc

25.42 ± 0.38bcd

25.25 ± 0.43 cd

24.83 ± 0.14d

Leaf length/cm

14d

7.04 ± 0.37ab

6.84 ± 0.14abc

7.29 ± 0.14a

6.99 ± 0.40ab

6.77 ± 0.37abc

6.55 ± 0.61bc

6.31 ± 0.38c

42d

11.25 ± 0.46b

11.97 ± 0.81ab

12.22 ± 0.63a

12.01 ± 0.30ab

11.83 ± 0.05ab

12.05 ± 0.15a

12.15 ± 0.28a

Leaf width/cm

14d

3.52 ± 0.10abc

3.63 ± 0.10ab

3.60 ± 0.06ab

3.69 ± 0.11a

3.37 ± 0.13c

3.43 ± 0.25bc

3.38 ± 0.04c

42d

5.96 ± 0.52a

6.46 ± 0.03a

6.30 ± 0.38a

6.11 ± 0.25a

6.27 ± 0.13a

6.00 ± 0.25a

5.96 ± 0.33a

Leaf length×Leaf width/cm²

14d

24.96 ± 1.92abc

24.89 ± 0.56abc

26.28 ± 0.85a

25.83 ± 2.33ab

22.87 ± 2.09abc

22.57 ± 3.66bc

21.36 ± 1.54c

42d

67.29 ± 7.96b

77.46 ± 4.97a

77.21 ± 7.87a

73.39 ± 2.74ab

74.23 ± 1.24ab

72.63 ± 3.38ab

72.45 ± 4.81ab

SPAD

14d

65.90 ± 1.68c

69.24 ± 2.16a

68.85 ± 0.55ab

66.32 ± 0.47bc

64.24 ± 2.94c

69.10 ± 0.21ab

64.04 ± 1.28c

42d

61.43 ± 1.73c

63.87 ± 0.09b

62.88 ± 0.32bc

65.92 ± 0.83a

63.96 ± 0.91b

63.33 ± 1.07b

63.85 ± 0.79b