Title : Development of turmeric (Curcuma spp.) from a little-known crop to high value medicnal crop in Southern USA
Abstract:
Turmeric (Curcuma spp.), used in Indian medicine for over 4000 years, is now gaining popularity in the US as a health supplement to combat inflammatory diseases, memory loss, and immune deficiency, among many others. A lack of high curcumin turmeric varieties adapted to the southeastern US and production technology are a major limitation to its production in the US. Therefore, field trials were conducted between 2007 and 2022 at Alabama A&M University to develop turmeric crop for commercial production. A wide range of turmeric genotypes obtained from Vietnam and other sources were evaluated for identifying genotypes best suited for commercial production. In the first phase (2007-2012), 15 genotypes were evaluated for adaptation, yield, and curcumin content; in the second phase (2015-2019), 52 varieties of Vietnamese origin were assessed at university research stations and 12 farms across Alabama for developing high curcumin turmeric varieties to cater to the medicinal plants industry; and in the third phase (2019–2022) season extension methods (high tunnel, cold plasma, hot water, and heat pad treatments) were evaluated to extend the turmeric growing season to enable higher rhizome yields and curcumin accumulation. Five genotypes were planted in single-row plots arranged in a randomized block design with four replications. Three plants from the middle row of each plot were harvested to determine fresh & dry rhizome yields and their curcumin (HPLC) and Essential Oil (EO) components (by hydrodistillation and analyzed by gas chromatographic techniques). In phase 1 trials, the fresh rhizome yield ranged from 9 for CL9 to 28 MT/ha for CL7, and the genotypic differences were significant. The curcumin content varied from 0% in C. zedoaria genotypes to 2.5% in C. Longa genotype (CL6). The yield of Vietnamese genotypes ranged from 0 MT/ha (VN 21,23,24) to 18.1 MT/ha (VN 27). The total curcumin content varied between 0 for all black and white turmeric and 6.8% for red turmeric varieties. Rhizomes subjected to cold plasma, hot water, or heat mats sprouted a week to 4 weeks earlier and produced higher rhizome yields than the control. Production in high tunnels extended the growing season by 4 to 6 weeks, resulting in 8 to 26% higher yield and curcumin content compared to those grown in open fields. The essential oil content varied between 0.204% (CL10) and 0.695% (CL9). The major components in the essential oils were α-phellandrene (3.7-11.8%), 1,8-cineole (2.6-11.7%), α-zingiberene (0.8-12.5%), β-sesquiphellandrene (0.7-8.0%), ar-turmerone (6.8- 32.5%), α-turmerone (13.6-31.5%), and β-turmerone (4.8-18.4%). In another study, the dominant EO components were curzerone (14.7-18.6%), germacrene (10.7-14.7%), 1,8-cineole (5.2-11.7%), ar-turmerone (8.3-36.1%), α-turmerone (12.7-15.2%), β-turmerone (5.0-15.4%), α-zingiberene (4.6-13.9%), and β-sesquiphellandrene (4.6-10.0%). Turmeric has commercial production potential in Alabama and perhaps the southeastern US. The distinctly different oil components in turmeric varieties studied could be potent against different diseases, particularly cancers.
