ABSTRACT OF Ph. D THESIS OF Dr. ARCHANA CP

Title of Thesis: Scaling up of Microrhizome and Minirhizome Technology for Disease Free Planting Material Production in Ginger and Turmeric

                                     Dr. ARCHANA CP

 

Ginger (Zingiber officinale Rosc.) and Turmeric (Curcuma longa L.) belonging to the family Zingiberaceae are two commercially important medicinal spices. These are rhizomatous perennials grown as annuals. Ginger is thought to have originated in the tropical jungles of Asia and commercially grown in India, China, South- East Asia, West Indies, Mexico, Africa, Fiji and Australia. Turmeric is a native of Southeast Asia. In ancient India, ginger was considered as Mahoushadi (great cure). Turmeric, the golden spice- the dried rhizomes of C. longa, is famed as the spice of life. It has strong association with socio-cultural life of Indian subcontinent and was described as ‘herb of sun’ by people of Vedic period.

The productivity of ginger and turmeric in India is decreased due to many diseases that affect the quality and quantity of the rhizome produced. In field, ginger and turmeric are prone to a number of pathogens and diseases of soil-borne and rhizome-borne nature. The success of these crops mainly depends on the use of clean, good quality seed material. The objective of the present study was to develop an efficient method for enhanced microrhizome production in three high yielding varieties each of ginger (IISR Mahima, IISR Rejatha and IISR Varada) and turmeric (IISR Alleppey Supreme, IISR Prabha and northeast cultivar Lakadong).

                

Culture initiation was successfully achieved using rhizome bits with at least two viable buds on MS basal medium supplemented with 0.1mgl^-1 Kinetin and 7gl^-1 agar and 15gl^-1 sucrose. The cultures were multiplied in MS medium supplemented with 0.5mgl^-1 NAA, 2mgl^-1 BA, 25mgl^-1 Adenine sulphate, 30gl^-1 sucrose and 8gl^-1 agar.

Single shoots isolated from the multiplied cultures were inoculated and used for studying the microrhizome induction potential under varying conditions. Almost all the cultures, irrespective of the cultivars, grown in higher sucrose levels showed microrhizome formation as evidenced by basal bulging of the pseudostem. Cultivar wise differences in microrhizome induction response were observed throughout the trials in both ginger and turmeric. In ginger and turmeric, higher concentration of sucrose, concentration of NH₄NO₃, light regime and supplementation of Abscisic acid were conducive for microrhizome induction. The type and size of culture vessel also influenced microrhizome induction. The development of microrhizome in different trial media was confirmed through visual observation of bulging of basal portion of the pseudostem and was further confirmed using anatomical and histochemical techniques. Micorhizomes showed all the characters of conventional rhizome, like presence of starch grains, oil cells etc. 

                                       

After three months of in vitro growth, the microrhizome induced plants were planted out in the nursery and after a season of growth, minirhizomes formation was achieved. Comparative field evaluation of microrhizomes, micropropagated rhizomes, minirhizomes and conventional rhizomes indicated superior yield performance of minirhizomes.

The chemical constituents of microrhizomes, micropropagated rhizomes, minirhizomes and conventional rhizomes were compared using various phytochemical tools like Thin Layer Chromatography, Gas Chromatography and High Performance Liquid Chromatography and qualitative similarity could be established. The genetic stability of microrhizome derived, micropropagated, and minirhizome derived plants with conventional rhizome derived plants was confirmed using RAPD markers. The pathogen free nature of microrhizomes and micropropagated rhizomes was confirmed by in vitro plant pathological screening using disc culture method on Potato dextrose agar medium, Plate count agar medium and triphenyl tetrazolium chloride medium.

In short, the microrhizome and minirhizome technologies developed in the present study could be used for the large scale production of genetically stable and pathogen free planting materials in ginger and turmeric within a short period of time without compromising the quality and quantity of the produce. These high quality rhizomes can be used in various fields of research for the identification, comparison and isolation of different components and for the conservation and exchange of pure germplasm.