Comparative evaluation of different species of oyster mushroom suitable to Kerala

Abstract

he present study entitiled “Comparative evaluation of different species of Oyster mushroom suitable to Kerala” was carried out in the College of Agriculture, Padannakkad during 2019-2021 with the objective to identify the oyster mushroom species best suitable for cultivation under five agro-ecological zones of Kerala. Five species of Oyster mushrooms were selected for the study viz., Pleurotus florida, P. djamor, Hypsizygus ulmarius, P. sajor-caju and P. citrinopileatus. To evaluate the yield performance, five species were cultivated in farmer’s field of five agroecological zones of Kerala. The study also aims to evaluate the proximate constituents and medicinal components present in oyster mushrooms. Sensory evaluation and shelf life studies were also carried out. The sporocarps of five species of oyster mushrooms were studied for their morphological characters. P. florida produced white, delicate and fleshy sporocarp with an average weight of 11.71 g. P. djamor produced pinkish white leathery sporocarps with smaller pileus having very short stipe (0.8 cm). H. ulmarius produced creamy white fleshy sporocarps with significantly large pileus having average size of 7.0 cm x 7.52 cm. P. sajor-caju produced greyish white leathery sporocarp. P. citrinopileatus produced golden yellow delicate sporocarp with comparatively short stipe. The average size of pileus was 5.45 cm x 6.17 cm. Microscopic observations of hyphae and spores of five species of oyster mushrooms shows that hyphae of all the five species were septate, branched and hyaline with clamp connections. The width of the hyphae of all the five species ranged from 1.5- 4.5 μm. Basidiospores of P. florida and P. djamor recorded 7-12 μm in length and 2-5 μm in width whereas, H. ulmarius and P. sajor-caju produced spores with dimension of 8-12 μm× 3-6 μm. P. citrinopileatus produced spores with dimension of 7-10 μm× 2-3 μm. 141 Two substrates namely paddy straw and rubber sawdust were evaluated for the cultivation of five species of oyster mushrooms. Total yield from three harvests were significantly less in paddy straw, (954.66 g) compared to rubber sawdust which has given a yield of 1306.40 g. The yield recorded was highest for H. ulmarius cultivated on both paddy straw and rubber sawdust (1233 g kg-1 and 1611 g kg-1 respectively) which was followed by P. florida (1148.30 g kg-1 and 1582.66 g kg-1 respectively). It has been evident that selection of substrate significantly affected time taken for complete spawn run, time taken for pin-head formation, time taken for first harvest, total crop period and total yield from three harvests. The present study revealed that both the substrates viz., paddy straw and rubber sawdust were suitable for the cultivation of oyster mushrooms. So, both the substrates can be selected for cultivation based on the ease of availability and cost. In the present study, the suitability of five species of oyster mushrooms in five agro-ecological zones of Kerala were evaluated by cultivating the mushroom species at coastal plains, midland laterites, foothills, high hills and Palakkad plains. H. ulmarius was found to be the best suited oyster mushroom species for cultivation in coastal plains (102.99 % BE), foot hills (92.73 % BE) and high hills (123.30 % BE). In midland laterites and Palakkad plains, highest BE of 82.70 (%) and 103.80 (%) respectively were obtained from P. djamor. P. djamor, although reported to be performing well under warm conditions, yielded well under midland laterites and Palakkad plains. This may be due to low relative humidity and comparatively higher temperature in these zones. Earliness in primordial initiation (14-19 days) and extremely fast growth also make this species promising for cultivation in Kerala especially during dry months. The proximate analysis of five species of oyster mushrooms was carried out and it revealed that mushrooms are rich source of proteins, carbohydrates, fibres, amino acids, vitamins and minerals with less fat content. The protein content was highest in P. sajorcaju (26.02 %) and the fibre content was highest in P. florida (26.20 %). Fat content was the least in H. ulmarius with 1.70 per cent on dry weight basis. H. ulmarius (31.27 %) recorded the highest carbohydrate content among the five species of oyster mushrooms. 142 P. florida recorded the maximum moisture content (90.97 %). Highest amino acid content of 19.40 per cent was recorded from P. sajor-caju Analysis of mineral components revealed that highest content of sodium (965 ppm) and potassium (7175 ppm) was present in P. djamor. P. florida recorded highest content of calcium (1000 ppm) and magnesium (4025 ppm) which supports healthy immune system and keep bones strong. Medicinal analysis confirmed that these mushrooms were rich in bioactive components. P. djamor recorded highest content of β-glucan (30.25 g per 100g) having antitumour and immunomodulation activities, β-carotene (3.70 μg per 100g) having antioxidant properties and lovastatin (370.75 μg per 100g) which reduce blood cholesterol. P. sajor-caju recorded highest glycoprotein (435.00 μg per 100g) and terpenoid (1.26 %) content. Sensory evaluation of five species of oyster mushrooms was done using sauteed mushroom recipe to evaluate the quality attributes and consumability of the species. H. ulmarius recorded highest scores for appearance (8.83), colour (8.75), texture (8.66), flavour (8.58) and taste (8.83) on a maximum score of 9. H. ulmarius scored 8.80 in terms of overall acceptability followed by P. florida (7.60). Overall, from this study it was found that oyster mushrooms, especially H. ulmarius and P. florida are highly favoured for consumption. Shelf life of five species of oyster mushrooms were undertaken both in room temperature (26±20C) and in refrigerated conditions (150C). In the present study, comparatively higher shelf life was observed on P. djamor and P. sajor-caju which could be stored for two days after harvesting in room temperature and three days in refrigerated conditions. The present study demonstrated the exploitability of five species of oyster mushrooms in Kerala conditions. All the five species can be cultivated under the five agro-ecological zones of Kerala but H. ulmarius, P. florida and P. djamor yielded well compared to P. citrinopileatus and P. sajor-caju. H. ulmarius was found to be the best 143 suited oyster mushroom species for cultivation in coastal plains, foot hills and high hills. In midland laterites and Palakkad plains, highest yields were obtained from P. djamor can be economically cultivated regarding the yield and earliness in fruitin