Fig 4. Chlorophyll a, b, a+b content, and chlorophyll a/b ratio of kratom cultivated under varying radiance.

FLD = field; GH = greenhouse. Data were pooled from three random replicates per treatment for four months (n = 36). Means sharing the same letter are not statistically different by Tukey’s honest significant difference test at P < 0.05. Error bars indicate the standard error. NS = not significant.