EFFECT OF FARM WASTE SUBSTRATES ON GROWTH, YIELD AND QUALITY OF OYSTER (PLEUROTUS SPP.) MUSHROOM

Abstract

Mushrooms are grown under natural conditions on living trees as saprophytes, on dead woody branches or artificially on agricultural and agro-industrial wastes. Oyster is rich in protein (30.4%), fats (2.2%), carbohydrates (57.6%), fibre (8.7%), ash (9.8%), vitamins and minerals salts. Oyster farmers are not conversant with suitable substrates to use or species to grow. The objective of this study was to determine the effect of farm waste substrates on growth, yield and quality of oyster mushroom and also the suitability of cereal grains substrates for spawn production. Two experimental sites namely; Kaimosi Agricultural Training Centre and Kapsabet Divisional Headquaters in Nandi Central District were used. The nine substrates were wheat straw (Trichum aestivum), maize cobs (Zea mays), bean husks (Phaseolus vulgaris), sugarcane bagasse (Saccharum officinarum), papyrus (Cyperus papyrus) and a combination of bean husks with each of the mentioned substrates separately. These were tested to determine the best farm waste substrates for oyster production. The substrates were mechanically shredded and sterilized and pH adjusted to 4.2 -7.5. Upon cooling the substrates were packed in 2 kg heat resistant polythene bags (10‟‟ x15‟‟) and pasteurized for 90 minutes using an oil drum and allowed to cool before being spawned with Pleurotus spp at the rate of 30 g per 2kg substrate. To determine the best cereal grain substrates for spawn multiplication, four cereal grain types namely, sorghum, corn, wheat and millet were tested for their suitability. The experiment was laid out as Completely Randomized Design - 2 oyster spp. x 9 media combinations (substrates) x 3 replicates. The inoculated bags spawned with Pleurotus spp were incubated in an incubation room with relative humidity of 70-80% and temperature of 22-300 C for 3 weeks to allow rapid mycelium colonization, pin head formation and subsequent emergence of fruiting bodies. Parameters observed were both fresh and dry weights, the rate of mycelium colonization, time taken for pinning, days to maturity, height of stipe, stem diameter, cap diameter, and Biological Efficiency. Quality of oyster mushroom was determined based on biochemical and microelements content at Kenya Industrial Research and Development Institute Laboratories. Data analysis was subjected to analysis of variance using general linear model of statistical analysis (SAS 2000) package. Treatment means were separated by multiple comparisons using Tukey‟s Honest Difference. Results showed that the best substrates in terms of growth, yield, and biological efficiency were maize cobs followed by wheat straw and sugarcane bagasse respectively. A combination of maize cobs with bean husks also proved to be a superior substrate. Sorghum (Sorghum bicolar) grains were found to be the best cereal grains substrates for spawn multiplication. Maize cobs are recommended as the best substrate for oyster (Pleurotus spp.) cultivation while sorghum grains are recommended as the most suitable cereal grains for oyster spawn production. White oyster are recommended for cultivation due to its faster rate of colonization on cereal grains during spawn multiplication. Analysis of biochemical and micro-element (nutrient) content revealed that oyster contains the much needed proteins, vitamins and mineral salts and hence this study recommends cultivation and consumption of oyster which will address the current protein deficit in most rural areas.