Yield improvement in the cultivation of Agrocybe aegerita using commercial and naturally occurring strains from different continents

UHART, M; ALBERTÓ E.

San Pablo, Brasil

Simposio; III Simposio Internacional sobre Cogumelos y Fungos Medicinales; 2006

Astract: A. aegerita is an interesting edible mushroom cultivated in Europe, Central America and Middle East. It is currently recognized as a complex including several species with similar morphology, which we are studying under several approaches. The edible mushroom A. aegerita is appreciated for its taste and intense aroma. It is cultivated in Europe and Asia using different methods and substrates as wheat straw and sawdust. Despite its excellent culinary properties, its cultivation has not been widely extended due to the low yields currently obtained, which do not normally exceed 60-80 %. For this reason, our aim was to study the yield variability in an important number of strains from a wide range of geographic origins; to determine the optimal substrate and to evaluate the production when using a casing layer to improve yields and make this species achieve crops that aloud its cultivation in a commercial scale. Three experiments were carried out: first, non-supplemented wheat straw or willow sawdust were used as culture substrates, using two commercial and one naturally occurring strains; second, the use of casing layer was compared among five commercial and twelve natural occurring strains. In a third experiment, and considering the results of the first experiment, wheat straw supplemented with 20 % rolled oats or 20 % soybean flour was used as substrate with the aim of evaluating the effect in production. 1 kg (wet weigh, 300 g dry weigh) bags were autoclaved. The casing layer contained 90% black earth and 10% peat, and was tindalized after stabilizing to pH 7. Incubation was carried out at 25°C in obscurity, during 55 days. After 40 incubation days, a 4 cm casing layer was added to 50 % of the bags. Fruiting conditions were: 18°C, 90% Hr, 9 hs photoperiod and spray irrigation. The highest biological efficiencies (between 62 and 72%) were obtained without casing layer, using the commercial strains 571/03 and 587/03, and naturally occurring strains 9/98, 621/04 and 622/04. In general, the use of a casing layer induced the production of basidiocarps with a bigger pileus diameter. In the third experiment the use of casing layer and sawdust were discarded, using as a substrate supplemented wheat straw and reducing the number of strains to those with highest yields. Two naturally occurring and one commercial strain were used for this experiment. Cultivation methods and conditions were the same as described above; with the only difference that incubation time was reduced to 40 days. Yields were raised significantly in 217, 147, and 143 % with soybean flour, and 119, 47 and 73% with rolled oats. The maximum biological efficiency achieved was 179 % using a natural occurring strain from Asia and soybean flour supplementation. The yield values now obtained allow considering this species for cultivation in a commercial scale. Indeed, this study evidences the importance of natural occurring strains and their germoplasm conservation.