Figure 1.

Plant growth characteristics and K content of tomatoes grown under red or/and blue supplemental lighting or without supplemental lighting at low K or normal K level. (A) The increase percentage of growth. (B) K content in tomato root, leaf, and fruit at 33, 47, and 61 DAA (days after anthesis). Error bars represent standard deviations of the means of three independent replicates. Different letters indicate significant differences between treatments by Duncan’s multiple range test (p ≤ 0.05). FW: fresh weight, DW: dry weight, SPAD: soil plant analysis development, leaf chlorophyll content, CK: natural light, R: supplemental 660 nm red light, B: supplemental 430 nm blue light, RB: supplemental red combined with blue light with ratio of 3:1, K: normal potassium supply, –K: low potassium supply.