Improvement of red ginger (Zingiber officinale Rosc.) through in vitro and in vivo studies.

Abstract

Red ginger (Zingiber officinale Rosc.) stands out among ginger types, garnering global recognition for its attractive red rhizome and potent medicinal attributes. Because of its slender rhizome and comparatively lower yield, it has yet to gain popularity among ginger cultivators. Crop improvement strategies, such as polyploidy induction, hold the potential to enhance the rhizome size, yield, and quality traits of red ginger. The study commenced with the morphological and biochemical characterization of 17 red ginger genotypes, comprising 14 Indian, two exotic lines, and the released variety IISR Varada. The results uncovered the significant difference in the growth, yield and quality parameters between the red ginger genotypes and IISR Varada. The study facilitated the identification of morphological and biochemical diversity among both exotic and indigenous red ginger genotypes. Among the genotypes, the highest yield per plant was recorded in Coll. No. 9073 (807.50 g) followed by Acc. 838 (625.00 g). Biochemical characterization of red ginger genotypes revealed that the highest essential oil and oleoresin contents were recorded in G9, at 4.30 % and 10.34 %, respectively. Among the exotic red ginger genotypes, the highest essential oil was recorded in Acc. 850 (3.89 %); the highest oleoresin content was observed in Acc. 899 (7.19 %). Among the genotypes, the lowest crude fibre content was observed in IISR Varada (4.90 %), whereas the highest was in G1 (10.47 %). The maximum percentages of 6- gingerol, 8-gingerol, and 6-shogaol were recorded in the red ginger genotypes Coll. No. 9073 (1.33 %), Acc. 844 (0.17 %), and G9 (0.18 %), respectively. The major compound identified in the essential oil was α-zingiberene, with the highest content reported in Acc. 845 (30.46 %). The high yielding genotype of Indian and exotic red ginger i.e., Coll. No. 9073 and Acc. 899 were selected as best performing genotypes. The second objective was to genetically improve red ginger through in vitro and in vivo polyploidy induction using colchicine. An efficient in vitro regeneration system was standardized for Indian and exotic red ginger genotypes. The maximum shoot multiplication was observed at a concentration of 5.0 mg L -1 BAP in exotic red ginger, while in Indian red ginger, it was observed at a BAP concentration of 3.0 mg L -1 . For in vitro polyploidy induction, colchicine concentrations of 0.00, 0.025, 0.50, 0.75 and 0.10 % at 24 and 48 h was used. The in vitro induction of polyploidy was found to be more effective compared to the in vivo method, resulting in a total of five tetraploids (2n=44). The highest tetraploidy induction was observed in the treatment using 0.10 % colchicine for 48 h, under in vitro treatment. For in vivo polyploidy induction, colchicine concentrations of 0.00, 0.05, 0.10, 0.15 and 0.20 % at 24 and 48 h was used and a single tetraploid (2n=44) was identified in Indian red ginger for 0.15 % at 24 h. The induced tetraploids exhibited increased vigor,improved morphology and stomatal parameters, and enhanced yield. The identified polyploids need to be tested for yield under multi-environment before commercial scale adoption.