MSc

The present investigation on ‘Biology and cultivation of Ganoderma spp.’ was conducted at College of Agriculture, Vellayani, Thiruvananthapuram during the period 2011-2013. The aim of the experiment was to study the biology of indigenous species of Ganoderma and to standardize techniques for the cultivation of this medicinal mushroom.
Forest and homestead areas across the state were surveyed during the rainy season of 2011 and 2012 and 20 samples of Ganoderma fruiting bodies belonging to different stages of growth were collected. Three isolates of Ganoderma were obtained in pure culture and were named as VG-1, VG-3 and VG-7 and two isolates namely DMR-G and Vellayani local were procured from Directorate of Mushroom Research, Solan, HP and the Instructional farm, Vellayani respectively. The DNA of the three cultures was isolated and sequenced and molecular characterization was done and their identity was confirmed and a phylogenetic tree was prepared.
Among the cultures, Vellayani local was the fastest growing one which completed its in vitro growth in a week followed by the isolate VG-7 and so these cultures were selected for further studies.
Carrot agar (CA) medium was most suitable for the growth of Ganoderma spp. Physiological studies revealed that a slightly acidic pH of 6 and a temperature range of 30-35 oC were best suited for the in vitro growth of Ganoderma spp. The intensity of light had no significant effect on mycelial growth.
Wheat grain was the best among the different spawn substrates tested since it took least time (12 – 15 days) for complete spawn run, followed by sorghum and paddy which completed the spawn run within 16 and 20 days respectively.
Among the bed substrates evaluated, sawdust (90%) + rice bran (10%) took the least time for complete mycelial colonization. The substrate sawdust (80%) + wheat bran (20%) was best suited for pinhead initiation of both the isolates. It was also observed that sawdust (78%) + rice bran (20%) + CaCO3 (2%) was ideal for early fruiting of both strains of mushrooms, below 21 days. The substrates based on wood chips were not found effective for pinhead initiation and thus sporocarp production was not observed.
Among the cultures, total crop growth period was the least for Vellayani local whereas VG-7 recorded maximum yield in all the substrates evaluated. The highest yield of VG-7 was 27.41g which was obtained in the substrate sawdust (80%) + rice bran (20%) and the highest yield recorded for Vellayani local was 18.34g in the substrate sawdust (80%) + wheat bran (20%) on fresh weight basis.
Among the two isolates, VG-7 recorded maximum biological efficiency in all the substrates evaluated. The highest biological efficiency of VG-7 was 6.59% which was obtained in the substrate sawdust (80%) + rice bran (20%) and 4.41% for Vellayani local in the substrate sawdust (80%) + wheat bran (20%).
Submerged culture production was done in two liquid media namely carrot broth (CB) and oatmeal broth (OMB). Vellayani local yielded 9.86g and 10.01g in carrot broth and oatmeal broth respectively while VG-7 gave a yield of 11.83g and 12.35g in CB and OMB respectively per 100 ml medium used.
As part of the investigation, 20 species of Ganoderma was collected and described, Vellayani local was found to be the best Ganoderma culture based on in vitro growth; carrot agar was the most suited medium; an acidic pH and a temperature range of 30-35oC favoured the growth; wheat was the most suitable spawning material; sawdust substrates amended with bran was the most efficient bed material and VG-7 was superior in terms of biological efficiency.