Studies on morphology, taxonomy, cultivation and nutritive value of some local saprophytic edible mushrooms.

Taxonomonic studies of some edible mushrooms growing in the wild were carried out in the field and in the laboratory, with the objective of identifying those with the potential of being cultivated under natural ambient tropical conditions. Morphological features and physiological aspects of the specimens collected were the main taxonomic criteria. Three out of the four local edible mushrooms collected and identified namely, Auricularia auricula - judae (st. Amans), Coprinus cinereus (Schaeff) S. Gray slat. and Volvariella volvacea (Bull.ex.Fr). Singer. were found growing on sisal waste compost under natural environmental conditions at Alavi and Kingolwira sisal estates while Pleurotus flabellatus (Berk and Br.) Sacc was found growing on the bark of a dead Ficus benjamina tree at the University of Dar es Salaam campus. The sisal organic waste nutritive compositions as substrate for growing some local edible mushrooms was investigated. The dried sisal waste was composted under natural environmental conditions and was ready within 20 days. The optimum temperature during composting ranged from 50 - 60 °C. The main chemical constituents of dried sisal waste prior to composting were, total fibre (lignin, cellulose and hemicellulose) about 83 %, total nitrogen 1.75 %, total carbon 52 %, with a C:N ratio of about 30:1. The chemical constituents of the compost at maturity were, total fibre (lignin, cellulose and hemicellulose) about 54 %, total nitrogen 1.0 %, total Carbon about 22 %, with C:N a ratio of about 21.7:1 and pH of 7.4. The physical qualities of the mature sisal waste compost were, a dark brownish colour with white spots, absence of NH3 smell and lack of greasiness. The composting process showed that the major chemical components of sisal organic waste are biodegradable illustrated by a narrowing of the C:N ratio. The growth of some local edible mushrooms on sisal waste under natural ambient conditions and their production of fruiting bodies was tested. The results show that biological efficiency (B.E %) of Coprinus, cinereus, Pleurotus flabellatus and Volvariella volvacea grown on sisal waste compost differed significantly (p < 0.05). Coprinus cinereus gave the highest B.E. of 68 %, followed by Pleurotus flabellatus with 64 %. The lowest B.E. of 28 % was obtained from Volvariella volvacea. The results also show that the B.E. (74 %) of Pleurotus flabellatus grown on non composted sisal waste was significantly higher (P < 0.05} than that grown on the composted sisal waste. The nutritive value of the local edible mushrooms cultivated on sisal waste was assessed. The nutritional compositions of the three species differed significantly (p < 0.05}. All three species on a dry weight basis contained considerable amounts of crude protein (17 - 28%); carbohydrates (50 - 62 %), crude fibre (6.6 - 11 %), vitamin C (33 - 55 mg/100g dry weight) and minerals (5.2 - 3232mg/100g dry weight). However, they were low in fat (1.0 - 3.3 %) and energy value (302 - 315 Kcal/100g dry weight). It was concluded that, the four local edible mushroom species identified represent some of the existing resource which can be exploited for cultivation. Sisal organic waste, being a lignocellulosic material may be a potential substrate for mushroom cultivation. Cultivation of the three local edible mushrooms on sisal waste compost under ambient natural environmental conditions using adapted local technology was feasible. Also the three local edible mushrooms are good sources of protein, vitamin C and minerals.