MSc

The present study entitled “Suitability of Pleurotus ostreatus (DMRP-30) for
cultivation in Kerala” was conducted at AICRP on Mushroom Laboratory, Department of
Plant Pathology, College of Agriculture, Vellayani during 2020-2022 with an objective to
standardize the spawn production and substrate for the unexploited Pleurotus ostreatus
(DMRP-30). The culture was initially procured from ICAR-DMR (Directorate of
Mushroom Research), Solan and used for spawn preparation followed by cultivation on
paddy straw.
Morphological characterisation of P. ostreatus (DMRP-30) revealed that the
sporocarps, were white, moderate to big oyster shaped (7.87 cm x 5.32 cm) with
eccentric, slightly pubescent stipe (3.85 cm thick). The spore print was white. The studies
on microscopic characters disclosed that hypae (2.32 μm width) was hyaline, septate,
with numerous clamp connections. The basidia (21.48 μm x 6.11 μm) were clavate with
tetra sterigmata and four smooth elliptical basidiospores (8.85 μm x 4.46 μm).
Cultural and physiological studies showed that potato dextrose agar was the best
medium for mycelial growth of P. ostreatus with a growth rate of 1.11 cm day-1
and took
minimum period for completion of growth in Petri dish (9 days). The optimum
temperature and pH was identified as 30 ℃ and 7-7.5 respectively. The lower
temperature of 20 ℃ and acidic pH of 4 retarded the mycelial growth. Maximum
mycelial biomass was obtained from malt extract broth and oatmeal broth at 21 and 30
DAI respectively (0.6 and 0.8 g mycelial dry weight).
Among various spawn substrate (grains) viz., paddy, wheat, sorghum, maize and
ragi, paddy was found to be the best spawn base with a thick fluffy mycelial growth,
minimum days for complete mycelial colonization (18 days) and minimum contaminants.
The total yield from beds prepared with paddy grains spawn was also higher (644.67 g
kg-1
of substrate) with out any contaminants compared to sorghum grains which was on
par.
Evaluation of various substrates viz., paddy straw, rubber saw dust, coir pith
amended with rice and wheat bran (10 %) and neopeat for production of P. ostreatus in
two seasons showed paddy straw as the optimal substrate with a maximum yield of
585.60 g (April) and 761.50 g (September) from three harvests. The sporocarp production
in September took minimum period with bigger sporocarps and enhanced yield when
compared to April. The maximum number (63.0) and weight of sporocarps (7.80 g) was
recorded from mushrooms harvested from paddy straw substrate followed by neopeat and
sawdust. The coirpith amended with wheat bran and rice bran beds failed to produce
sporocarps due to heavy contamination with Trichoderma spp. Pest like sciarid flies,
phorid flies, staphylinid beetles and slugs were predominant during the sporocarp
formation stage in the different substrates used. The major fungal contaminants observed
were Trichoderma spp. and Coprinus spp.
The proximate analysis of P. ostreatus revealed the constituents including
moisture (83.50 %) carbohydrate (38 %), protein (13 %), fibre (5.16 %) and fat (2.17 %).
The organoleptic characters of P. ostreatus was compared to P. florida and H.
ulmarius where sensory rating scores for appearance, colour, flavour, texture and taste
were done. P. ostreatus was found to be highly acceptable and preferred with 40 per cent
evaluators liking it very much compared to P. florida (30 %) and H. ulmarius (20 %).
Mushrooms stored in refrigerated condition (15 ℃) had better shelf life than those
stored at room temperature (28 ± 2 C). The packaging material (polypropylene – 0.20”
thickness) enhanced the keeping quality of P. ostreatus both at room temperature and
refrigerated condition compared to polyethylene ( 0.15” ). Maximum shelf life (4 days)
was observed when sporocarps were packed in perforated polypropylene and kept in
regulated condition at 15 ℃.
The study indicated that the strain DMRP - 30 of P. ostreatus can be successfully
cultivated in Kerala using the locally available substrates for spawn production and
cultivation. Good yield, proximate constituents and better shelf life could contribute to its
consumer and market acceptability in the state.