Induction of in vitro micro rhizomes and assessment of yield, quality, and clonal fidelity in ex vitro established plants of ginger (Zingiber officinale Rosc.)

Abstract

In vitro micro rhizome technology is a highly effective approach in combating seed-borne diseases and ensuring the production of healthy and high-quality planting material in ginger (Zingiber officinale Rosc.). To gauge the efficiency of micro rhizome production and their viability ex vitro, an experiment was conducted on several ginger varieties viz., IISR Varada, IISR Mahima, IISR Rejatha, and Karthika, at ICAR- Indian Institute of Spices Research, Kozhikode, Kerala, India. This experiment adhered to established protocols and standardized procedures. All four varieties exhibited varying rates of micro rhizome production after 180 days of culture. Among these, IISR Varada demonstrated the highest mean weight of cultured plant mass (96.0 ± 4.41 g), followed by Karthika (91.4 ± 5.72 g), IISR Rejatha (78.45 ± 5.59 g), and IISR Mahima (72.4 ± 3.56 g). IISR Rejatha exhibited the maximum number of micro rhizomes per bottle (11.35 ± 0.81) compared to IISR Mahima (10.8 ± 0.54), Karthika (9.8 ± 0.58), and IISR Varada (9.0 ± 0.63). The highest total weight of micro rhizome and mean weight of a single micro rhizome per bottle were recorded in IISR Varada (32.6 ± 1.92 g and 3.9 ± 0.29 g, respectively), followed by Karthika (27.1 ± 1.19 g and 2.9 ± 0.16 g, respectively), IISR Rejatha (27.0 ± 1.79 g and 2.5 ± 0.18 g, respectively) and IISR Mahima (24.5 ± 1.10 g and 2.4 ± 0.16 g, respectively). Besides, IISR Varada, followed by Karthika, emerged as the most promising varieties for micro rhizome production in terms of their multiplication rate. The evaluation extended to the first and second-generation progenies of micro rhizomes from IISR Varada. Results indicated the successful establishment of first-generation micro rhizomes in grow bags and second-generation micro rhizomes in the field, employing both direct planting and transplanting methods. Assessment of quality parameters revealed that the second-generation (V2) transplanted plants of micro rhizomes of IISR Varada exhibited the highest essential oil content 0.78%. The total phenolic content was highest in second-generation (V2) rhizomes directly planted in soil (23 mg GAE/g), whereas the first-generation micro rhizomes raised in grow bags registered the highest total flavonoid content (TFC) of 1.39 mg QE/g. Moreover, the genetic fidelity test conducted on the first and second generations (V1 and V2, respectively) of micro rhizome-derived plants, using molecular markers, exhibited a monomorphic banding pattern similar to that of the mother plant, confirming their genetic stability.