e-mail: lethikimloansinhhoc@gmail.com

RESEARCHER, Dong Thap Muoi Agricultural Research & Development Centre; IAS.

Advisor: Dr. K. C. Puzari, Professor and Head, Department of Plant Pathology, Assam Agricultural University, INDIA

ASBTRACT

Phaeoacremonium parasiticum has been found to be associated with oleoresin deposition in Aquialaria malaccensis (Agar plant). Mass culture of P. parasiticum needs to be done for its economic and large scale production of Agarwood oil. P. parasiticum cultured on PDA petriplate at 30±1^oC, showed very slow growth rate. At 30 days after inoculation, the radial growth reached 6 cm to 7 cm, and showed a grey to greenish-grey colour, typical radial furrows were seen prominently form the back side of PDA plate. The Agar-agar slide culture of P. parasiticum under microscopic examination showed that at 5 days after inoculation, mycelium and circular mycelium were coloured, with septate hyphae, bearing branched or unbranched conidiophores. Conidiophores were approximately 10 µm to 65 µm in length, septate or aseptate, bearing the phialide. At 10 to 15 days after inoculation the hyaline, aseptate conidia aggregated in groups on the phialides of conidiophores with various shapes viz., oblong, ellipsoidal, obovoid or broadly oblong. The typical characteristic warts like droplets of P. parasiticum were also seen on mycelium. To find out the favourable material for mass culture of P. parasiticum, five different media including the liquid media viz., Potato Dextrose Broth (PDB), Host Extract (50%) + Potato Dextrose Broth (50%) (HE+PDB), and the solid media viz., Rice Bran (RB), Maize Meal (MM) and Wheat Bran (WB) were tested. Solid media were added with water at the rate of 70 ml/100g of solid substrate. The media were adjusted at pH of 6.5 and incubated at a temperature of 30±1^oC. The colony forming unit (cfu) counted (after 30 days of inoculation) showed that, the population density of P. parasiticum in liquid media like PDB was 7.23 log cfu/ml, and HE+PDB was 4.85 log cfu/ml. In solid media, the highest population density was in MM media with 9.56 log cfu/g, followed by WB media (9.50 log cfu/g) and RB media (9.38 log cfu/g). Artificial inoculation by tree drill method with the inoculum produced in MM media showed 100% success in development of typical symptoms of infection on A. malaccensis trees. After burning the woody disease samples on the flame, the emission of a light pleasant aroma was observed. It proved the pathogencity of the fungus cultured in MM. Hence, Maize Meal media (MM : Water = 100g : 70 ml) at pH of  6.5, incubation temperature: 30±1^oC for 30 days would be the standard technique for mass production of P. parasiticum. The inoculum (9.56 log cfu/g) can directly be used for artificial inoculation by Tree drill method for artificial oleoresin deposition in A. malaccensis.