Study on the formation and growth of white turmeric rhizomes (Curcuma aromatica Salisb.)

White turmeric has underground stems that develop rhizomes. It has been used as an Eastern traditional herb for a long time. As with many other monocotyledons, the growth of white turmeric is mainly due to the presence of the primary thickening meristem. Currently, the study of the primary thickening meristem, radial growth, and accumulation of secondary material as essential oil in turmeric rhizomes, including white turmeric, is still limited. In this study, we observed the anatomical structural changes in white turmeric in early growth stages in vitro : we counted the number of PTM layers, the number of vascular bundles, and the number of essential oil drops in the rhizomes and determined physiological and biochemical indicators, such as respiratory intensity, tuber diameter, fresh weight, dry weight, total sugar content, and starch level, according to each stage of early growth (0, 2, 4 and 6 weeks) of white turmeric. The results showed that at 0 weeks of age (resting buds), the PTM consists of 1-2 layers of cells, and there is no formation of vascular bundles and essential oils in tubers. At 2 weeks of age, the PTM consists of 6-7 layers of cells, and there is the formation of vascular bundles and the appearance of essential oil droplets in the parenchyma. The number of PTM cell players decreases to 3-4 layers at 4 weeks of age and 2-3 layers at 6 weeks of age, but the tuber diameter and the number of vascular bundles increase rapidly. Along with an increase in fresh weight, dry weight, starch content, and the number of drops of essential oils, there was a decrease in the sugar content and respiratory intensity in the rhizome. The relationship between the number of PTM layers, the number of vascular bundles and diameter, sugar content, starch, and the number of essential oil droplets was also discussed.