Shiva et al. (2004)

of ginger germplasm under in vitro conditions by slow growth was standardized at IISR, Calicut (Geetha et al., 1995; Nirmal Babu et al., 1996; Geetha, 2002). By this method, ginger could be stored up to one year without subculture in half-strength Murashige and Skoog (MS) medium with 10 gl-1 each of sucrose, and mannitol in sealed culture tubes. The survival of such stored material is around 85%. At IISR, over 100 unique accessions of ginger are being conserved under in vitro gene bank as medium-term storage of germplasm (Ravindran et al., 1994; Geetha, 2002). The possibility of storage at relatively high ambient temperatures (24—29°C) by subjecting the ginger and related taxa to stress factors was explored by Dekkers et al. (1991). The increase in the subculture period was better with an overlay of liquid paraffin. After one year, 70 to 100% survival was seen.

Ravindran and coworkers (Anon. 2004) standardized the use of synthetic seeds in conservation. Synthetic seeds, developed with somatic embryos, encapsulated in 5% sodium alginate gel could be stored in MS medium supplemented with 1 mgl-1. g/l can be substituted for gl-1 throughout the chapter (and also in other chapters) Benzyl adenine (BA) at 22 ± 2°C for 9 months with 75% survival. The encapsulated beads on transfer to MS medium supplemented with 1.0 mgl-1 Benzylaminopurine (BAP) and 0.5 mgl-1 Naphthalene acetic acid (NAA), germinated and developed into normal plantlets (Sajina et al., 1997). The conservation of germplasm through microrhizome production was also investigated and it was found that microrhizomes can be induced in vitro when cultured in MS medium supplemented with higher levels of sucrose (9 to 12%). Such microrhizomes can be easily stored for more than one year in culture. Six-months-old microrhizomes can be directly planted in the field without any acclimatization. The microrhizomes can thus be used as a disease-free seed material and for propagation, conservation, and exchange of germplasm (Geetha, 2002). This microrhizome technology is amenable for automation and scaling up.

Cryopreservation is a strategy for long-term conservation of germplasm (Ravindran et al., 1994). Efforts are going on at IISR and NBPGR for developing such strategies. Cryopreservation of ginger shoot buds through an encapsulation-dehydration method was attempted by Geetha (2002). The shoot buds were encapsulated in 3% sodium alginate beads and pretreated with 0.75 M sucrose solution for 4 days and dehydrated in an air current from laminar airflow and then immersed in liquid nitrogen. Beads conserved like this on thawing and recovery exhibited 40 to 50% viability. The cryo-preserved shoot buds were regenerated into plantlets. The studies carried out at IISR showed that vitrification and encapsulation-vitrification methods are more suitable for the cryopreservation of ginger shoot buds (Nirmal Babu, unpublished data).

Characterization and Evaluation of Germplasm

A clear knowledge of the extent of genetic variability is essential for formulating a meaningful breeding strategy. Under a low-variability situation, selection programs will not yield worthwhile benefits. In any vegetatively propagated species the extent of genetic variability will be limited unless samples are drawn from distinctly different agroeco-logical situations. Studies on genetic variability for yield and associated characters in ginger indicated the existence of only moderate variability in the germplasm. Little variability exists among the genotypes that are grown in the same area; however, good variability has been reported among cultivars that came from widely divergent areas.

Ravindran et al. (1994) characterized 100 accessions of ginger germplasm based on morphological, yield, and quality parameters. Moderate variability was observed for many yield and quality traits (Table 2.17). Tiller number per plant had the highest variability, followed by rhizome yield/plant. Among the quality traits, the shogaol content recorded the highest variability, followed by crude fiber and oleoresin. None of the accessions possessed resistance to the causal organism of leaf spot disease, Phyl-losticta zingiberi. Quality parameters such as dry recovery and oleoresin and fiber contents

Table 2.17 Mean, range, and CV (%) for yield attributes and quality traits in ginger germplasm




CV (%)

Plant height (cm)

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