MSc

The study entitled “Evaluation and improvement of production technology of paddy straw mushroom (Volvariella sp.)” was performed in College of Agriculture, Vellayani during 2015-2017, with the objectives to explore the native isolates of Volvariella sp. and to study their morphological characters, improvement of techniques for production of paddy straw mushroom and to make an evaluation of the nutritional and organoleptic qualities. As a part of the study collections were made from various locations of Thiruvananthapuram and Kollam districts and thirteen different isolates of paddy straw mushroom were obtained.
Morphological studies of different isolates of paddy straw mushroom showed that the sporocarps have black colour during the egg stage which become ashy to purplish white on maturity. Pileus is sub-umbonate with regular margin having free, smooth, pale salmon to moderate brown gills and central, cylindrical stipe with bulbous base encased in a thick volva. Microscopic studies revealed septate hyphae without any clamp connection, bottle shaped cheilocystidia, club-shaped basidia with four ovoid pink/moderate brown basidiospores.
Cultures were isolated from the freshly collected mushrooms at egg stage through tissue culture technique and purified the cultures by hyphal tip method. Evaluation of cultural characters showed that the local isolate collected from Poonkulam had faster mycelial growth and it was taken as best isolate for further study. The morphological characters like size, weight of sporocarp of the selected isolate were also found promising.
Study on different substrates for spawn production recorded that wheat grain, sorghum grain and paddy grain supported thick and fluffy mycelial growth. Considering the keeping quality, easy availability and nature of mycelial growth paddy grains was selected as the suitable substrate for spawn production in Kerala conditions.
Comparison on the effect of different substrates for paddy straw mushroom production showed that paddy straw along with oil palm bunch waste on equal proportion amended with 5% gram flour was the best substrate for cultivation with a biological efficiency of 16.33%. Studies on the developmental morphology revealed that the fruiting body of paddy straw mushroom took 4-5 days for maturation from the pinhead emergence.
Evaluation of different supplements for paddy straw mushroom production showed that 200ppm IAA supplementation during spawn run period yielded maximum (10.78% increase in biological efficiency over control). Assessment of different bed systems on production of Volvariella sp. recorded polybag method as more user friendly with maximum yield. Phorid flies were observed as the major pest during cultivation period. The competitor moulds identified were Trichoderma sp., Aspergillus sp., Penicillium sp. and Coprinus sp.
Analysis for the proximate constituents in paddy straw mushroom exposed that it contains appreciable amount of protein (41.36 %) and fibre (16.98 %). Sensory evaluation was done using sauted mushroom recipe with Hedonic rating scale and observed that Volvariella sp. exceeded in colour, flavour, texture and taste attributes than Agaricus sp., Pleurotus sp. and Calocybe sp.
Molecular characterization of the best isolate was carried out using ITS sequencing and the blast sequence was analysed in ClustalX2 software. Dendrogram was also constructed using TreeView software showing the phylogenetic relationship. Best isolate was identified as V. hypopithys and deposited in Directorate of Mushroom Research, Solan with the accession number DMRO – 943.
The present study recommends that paddy straw mushroom can be successfully cultivated in Kerala using paddy straw and oil palm bunch waste in equal proportion as substrate having 5% gram flour amendment, supplemented with 200 ppm IAA on mycelial development stage by polybag method or wooden box method. Paddy straw mushroom was found to be high in terms of protein content and organoleptic attributes.