Growth characteristic and bioactive compound synthesis in aromatic ginger (Kaempferia galanga Linn) callus under ultraviolet B exposure and sucrose supplementation

The results showed that sucrose concentration affected most growth parameters and phytochemicals formed. The fresh and dry callus weight increased with increasing sucrose concentration in the media. Growth decreased with increasing sucrose concentration above the optimum concentration (30 g.L-¹). Growth parameters, including fresh callus weight and dry callus weight of K. galanga, were affected by the auxin type and UV-B radiation. Contrary to the observed growth parameters, the increasing sucrose treatment caused a 0.05-0.39 times decreased in total phenol content, 0.1-0.75 times total flavonoid content, 0.05-0.6 times EPMC content, and antioxidant activity 0.21-0.45 times compared to that without sucrose. UV-B irradiation increased the total phenolic content (TPC) and total flavonoid content (TFC) of the callus by 1.13 and 1.7 times, respectively, compared to untreated samples. Phytochemical outcomes, such as total phenols, flavonoids, EPMC levels, antioxidant activity, and PAL enzyme activity, were influenced by auxin and sucrose concentrations. While UV-B treatment boosted total phenolics, flavonoids, and antioxidant capacity in K. galanga callus, it did not significantly alter EPMC formation. The combined effects of sucrose concentration and UV-B irradiation had little impact on PAL enzyme activity.