MSc

Investigations on “In vitro production of microrhizomes in Curcuma aromatica Salisb.” was carried out at the Department of Plantation Crops and Spices and Department of Plant Biotechnology, College of Agriculture, Vellayani, Thiruvananthapuram during 2009-2011. The objective of the study was to standardize the method(s) for in vitro production of microrhizomes in Curcuma aromatica Salisb. so as to utilize them for rapid propagation and conservation of germplasm.
The investigations were carried out in two phases viz., (i) In vitro shoot multiplication and (ii) Microrhizome production. IISR accession of Curcuma aromatica from the germplasm collection of the Department of Plantation crops and Spices, College of Agriculture, Vellayani was used for the study.
For in vitro shoot multiplication rhizome bud sprouts was used as explants. Sprouted rhizhome bud of C. aromatica treated with Bavistin 0.2 per cent for 30 minutes and mercuric chloride 0.1 per cent for 12 minutes registered the highest survival percentage (87%). Murashige and Skoog’s medium supplemented with BA and NAA and agar 6.5 per cent was optimum for shoot multiplication. Maximum number of multiple shoots (12.4), and the longest shoot (6.03 cm) was obtained in 5 mgl-1 BA and 0.10 mg l-1 NAA.
For in vitro rooting, the shootlets produced in vitro were transferred to rooting media where half strength MS medium with IBA 0.2 mg l-1 favoured best rooting with regard to percent of cultures initiating roots (100%), number of roots (15.4) and root length (6.4 cm).
Mixture of coir pith compost and vermi compost (1:1 v/v) was identified to be the best potting medium for planting out and acclimatization, registering 100 per cent survival rate.
The in vitro multiplied tissue cultured plants were successfully established in the field. The plants were healthy and vigorous with cent per cent field survival and were morphologically uniform. 85

For microrhizome induction, three to four cm long shoots generated from in vitro shoot multiplication cultures were used as explants. Microrhizome formation was found to be controlled by the concentrations of cytokinins and sucrose as well as photoperiod during the culture.
BA 5.0 mg l-1 was identified as the best hormone for microrhizome induction with regard to number of microrhizome per culture vessel (4.8), fresh weight (247 mg) and dry weight (65 mg) of microrhizomes produced. Different concentration of growth regulators on microrhizome production showed that the number of shoots producing microrhizomes range between two to five.
Among the different levels of sucrose, 70 g l-1 was most effective for microrhizome induction as indicated by earliness in induction (37 days), maximum percentage (92 %) of cultures with microrhizome and highest number (5.5) of microrhizome per culture vessel. But maximum fresh weight (260 mg) and dry weight (70 mg) microrhizome was noticed at higher concentration of 80 g l-1.
With regard to various durations of photo period used for microrhizome induction, eight hours light was found better than others with respect to percentage (92 %) of cultures with microrhizome, number (5.5) of microrhizome per culture and fresh (220 mg) and dry weight (56 mg) of microrhizome.
Harvested microrhizomes from in vitro culture were germinated both in vitro and ex vitro. During in vitro germination, regeneration of microrhizomes was independent of size and weight and registered 83.3 per cent regeneration and survival. But in ex vitro germination, regeneration of microrhizomes was dependent of size and weight and larger microrhizomes (>150 mg) registered highest regeneration percentage (91.6 %) and survival percentage (75 %). With regard to growth parameters larger microrhizomes (>150 mg) performed better both under in vitro as well as ex vitro conditions. They recorded maximum shoot length (30 mm), highest rate of shoot growth (10 mm week-1), maximum fresh weight (160 mg) of shoot and dry weight (40 mg) of shoot during in vitro germination and highest rate of shoot growth (10 mm week-1), maximum shoot number (20 mm), maximum root number (4.0), maximum shoot length (39 mm), maximum root length (4.1 cm), maximum fresh weight (200 mg) of shoot and dry weight (50 mg) of shoot during ex vitro germination.