Chemical and biochemical changes in the rice straw substrate related to the morphogenesis, cropping patternand yield of Pleurotus florida (Block & Tsao.)
2001
Shashirekha, M.N. | Rajarathnam, S. | Bano, Zakia
Growth and yield of Pleurotus florida on rice straw were studied as a function of temperature. At an ambient temperature of 20˚C, a maximum bioconversion efficiency (yield to substrate ratio, both on a dry-weight basis) of 14.5% was recorded. The net yield was observed over 2–3 flushes, with an interflush period of ca. 7.d. Increase in bioconversion efficiency (BCE) decreased left-over spent substrate and increased the loss of growth substrate as CO₂ and H₂O. An increased solubility of the growth substrate was observed with increase in BCE. In general, increase in sugars, amino acids, and decrease in phenols, cellulose, hemicellulose and lignin were observed; however amino acids decreased at high levels of BCE. Likewise, the decrease in lignin content was not important above a 10% increase in BCE. Flush co-ordinated operation of the degradatory enzymes in the rice straw substrate was studied. Whilst CMC-ase, b-glucosidase, hemicellulase and protease showed a continuous increase over all the flushes, laccase showed a decline only after the first flush, reflecting the possible non-requirement for lignin degradation thereafter. The growth of the fruiting primordium into a mature fruiting body took 72.h was characterized by an active increase in cellulase(s), hemicellulase(s) and, protease in particular. Laccase activity declined. This observation is associated with the requirement for carbohydrates and protein for growth and development of the fruiting bodies. Hexosamine content in the rice straw substrate increased until the end of spawnrun and declined thereafter, in accordance with the fructification.
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