COMPARATIVE STUDY OF THE GROWTH AND YIELD OF THREE CULTIVATED Pleurotus SPECIES ON SELECTED TROPICAL TREES SAWDUSTS

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COMPARATIVE STUDY OF THE GROWTH AND YIELD OF THREE CULTIVATED Pleurotus SPECIES ON SELECTED TROPICAL TREES SAWDUSTS

ABSTRACT

The quest to boost dietary protein production from readily available and affordable sources is ever increasing in developing countries. The indigenous edible Pleurotus species (oyster mushrooms), which grow naturally on wood wastes, are potential protein supplements. However, little information is available on the usage of selected tropical trees for optimum mushroom cultivation. Therefore, this research was designed to investigate the growth and yield of oyster mushrooms on sawdust of selected tropical trees.

Mature stems of Mangifera indica L. (PTBG0000039360), Senna siamea Lam. (BISH0000032830) and Azadirachta indica A. Juss (BISH0000015188) were harvested and identity authenticated at the National Horticultural Research Institute (NIHORT), Ibadan. The samples were air-dried, separately milled into sawdust, composted and used as three substrates. The fourth substrate was the mixed bed derived from the mixtures of the three substrates in ratio 1:1:1 by weight. Three mushroom species (Pleurotus ostreatus, P. pulmonarius and P. tuberregium) were collected from Mycology Unit, NIHORT. A total of 108 polyethylene substrate bags (27 for each substrate) were filled with 300 g of the sawdust, each tightly packed, sterilised and inoculated with 30 g each of mushroom spawn. Mycelial growth was determined using standard method. Fruiting body production was obtained for the three mushrooms on all the substrates and sclerotia weight recorded at different Weeks of Composting Intervals (WCI) of 4, 8 and 12. Biological and production efficiencies were determined using mathematical methods. The experiment was a 4 x 3 x 3 factorial arrangement laid out in a complete randomised design with three replicates each. The data were analysed using descriptive statistics and ANOVA at p =0.05.

The longest and the shortest mycelial extensions (13.3 and 4.6 cm) were observed in P. pulmonarius grown on A. indica at 4WCI and 8WCI respectively. At 12WCI, the highest Fruit Weight (FW) of 86.8±1.2 g for P. pulmonarius was observed on S. siamea which was not significantly different from P. ostreatus (84.9±1.2 g) on M. indica. The most significant Biological Efficiencies (BE) of 82.7% and 80.9% for P. pulmonarius and P. ostreatus at 12WCI respectively were observed on S. siamea and M. indica. At 12WCI, the Production Efficiency (PE) was highest (42.8%) for P. ostreatus on M. indica and 41.1% for P. pulmonarius on S. siamea. Also, the highest mean sclerotia weight of 42.1±0.9 g was obtained for P. tuber-regium on M. indica at 12WCI. However, at 4WCI, the least FW (13.7±0.1 g) was in P. pulmonarius cultivated on S. siamea while the least BE (13.0%) was observed for P. pulmonarius on S. siamea. Also, the least PE value of 4.9% for P. pulmonarius was observed on S. siamea while the least sclerotia weight of 9.0±0.6 g was obtained on mixed bed. The longer the decomposition period of the substrate, the more significant was the yield.

The best substrate for the production of fruiting body of Pleurotus ostreatus and sclerotia of Pleurotus tuber-regium was Mangifera indica while Senna siamea was most suitable for Pleurotus pulmonarius.

Keywords: Biological and production efficiencies, Composting intervals, Oyster mushrooms, Tropical trees sawdust

CHAPTER ONE

INTRODUCTION

1.1        Mushrooms

The word mushroom is believed to have originated from the french word “mousseron” derived from the word moss (Mau et al., 1993). Mushrooms belong to the Kingdom Mycetae which are non-green, edible fungi and that they are large heterogeneous group with various shapes, sizes and appearance. They are macro fungi with distinctive fruit bodies which are visible to the naked eye (Alexopoulos and Mims, 1979). They are neither plants, due to lack of chlorophyll, nor animals because they store glycogen (Alexopoulos and Mims, 1979). Mushrooms are seasonal and highly perishable crop and contain about 90% moisture. They are non-traditional horticultural crops of high quality proteins, high fibre value, vitamins and minerals (Narayanasamy et al., 2009). Mushrooms gathered from farmlands, fields and meadows were valued as food (Quimio et al., 1990). They could be cultivated on composted substrates, chemically treated or untreated wood logs, or picked up in the field during the rainy season (Aletor, 1995; Kadiri, 1999; Kadiri, 2002). All edible fungi are saprophytes, and only the reproductive structure comes out of the substrate and forms a fruiting body which is visible, called mushroom. Although, some mushrooms are unpalatable and others even poisonous, the mushrooms of many species are not only edible but also delicious and nutritious (Chang and Miles, 1986; Chang and Miles, 1989).

1.2        Oyster Mushrooms

Oyster mushrooms are scientifically called Pleurotus and the latin name Pleurotus ostreatus means “sideways oyster”, referring to the oyster-like shape of the mushroom (Dike et al., 2011). Pleurotus species are found to be one of the most efficient lignocelluloses solid state decomposing types of white rot fungi (Baysal et al., 2003). Thus, many agricultural and industrial wastes can be utilized as substrates for the production of Pleurotus species (Baysal et al., 2003). They require shorter growth time when compared to other edible mushrooms, they demand few environmental controls, their fruiting bodies are not very often attacked by diseases and pests and they can be cultivated in a simple and cheap way (Jwanny et al., 1995; Patrabansh and Madan, 1997). Sawdust and sugarcane bagasse were once reported as the best substrates for growing of Oyster Mushroom than other agro-based substrates (Ahmed, 1998).

1.2.1 Pleurotus ostreatus

  1. ostreatus is an excellent producer of the industrially important enzyme laccase and also used for the decolorization of anthraquinone dye (Ho u et al., 2004). Although, it contains lower concentration of major elements like phosphorus, potassium and calcium but trace mineral elements like magnesium, boron, cadmium, iron and manganese are at a higher concentration than that of Agaricus bisporus (Vetter, 1994). It has extensive use in biodegradation (Adamovic et al., 1998), immunomodulatory, anti-hypocholesterolemic, anti-mutagenic and anti-tumour activities (Wasser, 2002a; Hossain et al., 2003; Lakshmi et al., 2004; Maiti et al., 2011).

1.2.2 P. pulmonarius

It is commonly known as the Indian Oyster, Italian Oyster, Phoenix Mushroom, or the Lung Oyster, is a mushroom very similar to Pleurotus ostreatus, the pearl oyster, but with a few noticeable differences (Stamets, 2000). The caps of this mushroom are much paler and smaller than that of P. ostreatus. It also prefers warmer weather than ostreatus and will appear later in the summer. Otherwise, the taste and cultivation of the two species is generally described as largely the same (Stamets, 2000). It is widespread in temperate and subtropical forests throughout the world. In the eastern United States, this species is generally found on hardwoods, while in the west it is commonly found on conifers (Stamets, 2000).

A polysaccharide called β-D-Glucan from P. pulmonarius reduced sensitivity to pain in mice (Baggio et al., 2010), a basis for new analgesic medications (Baggio et al., 2011). While a glucan from it showed potent anti-inflammatory and analgesic properties, a methanol extract of it displayed anti-inflammatory and antitumor activity (Jose et al., 2002; Smiderle, 2008). The extracts of P. pulmonarius may slow the proliferation of cancer cells and be useful as an adjuvant to cancer therapies and can halt the progression of diabetes (Badole et al., 2008; Wasonga et al., 2008; Lavi et al., 2010). It may be effective in the treatment of hay fever, cause a significant reduction in sneezing and nasal rubbing by inhibiting the release of histamine, can be used in the treatment of colitis and also inhibit coloncancer formation associated with colitis in mice (Yatsuzuka et al., 2007; Lavi et al., 2010; Lavi et al., 2011). Extracts of P. pulmonarius have antimicrobial properties (Ramesh and Pattar, 2010).

1.2.3 P. tuber-regium

It is a popular edible mushroom and is considered a profound health promoting mushroom in traditional Chinese medicine (Isikhuemhen et al., 2000; Huang, 2002). It has nutritive values and some medicinal properties which include relief for stomach ailments, fever, asthma, smallpox, high blood pressure, and cancer (Wong et al., 2011). It is believed by many Nigerians to be capable of curing ailments such as headaches, stomach pain, small pox, fever and chest pain (Oso, 1977a; Isikhuemhen and Okhuoya, 1995; Okhuoya et al., 1996). It is used in the Asaba area of Nigeria in herbal preparation for pregnant women to aid the development of foetus.

In Ghana, the sclerotia are used mainly for fattening of malnourished babies and as one of the ingredients in the embalming of dead bodies (Okhuoya et al., 1998). The fruiting bodies of P. tuber-regium is highly nutritive and very rich in protein, while sclerotium is rich in fiber, especially non-starch polysaccharides (Kadiri and Fasidi, 1990), mainly composed of bioactive β-glucans responsible for pharmacological actions (Cheung and Lee, 2000; Tao et al., 2006). It has antihyperglycemic, antihyperlipidemic, and antioxidant properties (Huang et al., 2012). Analysis of its sclerotia has shown the presence of Calcium, Magnesium, Iron and Zinc (Okhuoya and Ajerio, 1988).

1.3        Substrates for mushroom cultivation

 Mushrooms are grown on great variety of substrates. Mushroom substrate may be defined as lignocellulotic material which supports the growth, development and fruiting of mushroom and their choice depends on availability and cost (Chang and Miles, 1988a).  

 A lot of studies were reported on the various substrates for mushroom production namely straws of rice (Oryza sativa), wheat (Triticum vulgare), ragi (Elucine coracana), bazra (Pennisetum typhoides), sorghum (Sorghum vulgare), maize (Zea mays), wood of poplar (Populus robusta), oak (Quercus luecothricopora), horse chest nut (Aesculus indica), Acasia species, chopped banana pseudostem, cotton stalk, pea shells and poplar sawdust (Saidu et al., 2011). Most of the commercial producers of mushroom in Malaysia are currently using sawdust and rice husk (Saidu et al., 2011).

Substrates may also be obtained from various plant remnants without enrichments by expensive additives. Composted or uncomposted wheat and paddy straw, banana leaves, sugarcane bagasses and leaves, wheat bran, rice husk, sawdust etc can be used as substrate for growing mushroom (Gupta, 1986).

1.4       Choice of Oyster mushrooms

Oyster mushroom is the second most cultivated edible mushroom worldwide after Agaricus bisporus(Sánchez, 2010). Members of the mushroom genus Pleurotus form a heterogeneous group of edible species of high commercial importance (Georgios et al., 2004). It has economic and ecological values with medicinal properties (Gregori et al., 2007; Sánchez, 2010; Khan and Tania, 2012). It has abilities to grow over a wide range of temperatures utilizing various lignocelluloses (Sánchez, 2010).

Oyster mushroom cultivation also help in managing organic wastes whose disposal is very complicating and time consuming (Das and Mukherjee, 2007). It converts a high percentage of the substrate to fruiting bodies thus increasing profitability (Sanchez, 2010). Particularly, P. ostreatus requires a shorter growth time in comparison to other edible mushrooms, demands few environmental controls, their fruiting bodies are not often attacked by diseases and pests, and they can be cultivated in a simple and cheap way (Sánchez, 2010).

1.5       Choice of the selected tropical trees

 The selected tropical trees are mango (Mangifera indica), cassia (Senna siamea) and neem (Azadirachta indica) trees. They are readily available in the tropics and consequently, our environment. They have lignin and cellulose which support growth of mushrooms and are easily converted to sawdust during milling for mushroom cultivation. They can be easily colonized and degraded by edible mushrooms (Sánchez, 2010). They have medicinal and seasoning or flavouring properties (Lose et al., 2000; Kiepe, 2001; Subapriya and Nagini, 2005).

1.6       Statement of problem

Malnutrition cases occur in the most people of developing countries due to poverty level and their inaffordability in sourcing for animal proteins. Also, there is an increased demand for animal protein in these countries as a result of population explosion and proper diet.

1.6.1 Justification

Animal protein is beyond the reach of most people in developing countries because most of them live below poverty level (World Bank, 1992). Therefore, there is the need to find out an alternative source of protein due to malnutrition as a result of population explosion predicated upon by an increasing protein gap. More so, FAO recommended edible mushrooms as food that can contribute to protein nutrition of developing countries which depend largely on cereals (Islam et. al., 2009). Pleurotus species are one of the choice edible mushrooms that can be cultivated in the tropics (Quimio et al., 1990). They possess extensive enzyme systems that are able to degrade varieties of lignocellulotic materials (Baysal et al., 2003), thereby utilizing them for growth.

 

 

1.6.2Aim

 

 

COMPARATIVE STUDY OF THE GROWTH AND YIELD OF THREE CULTIVATED Pleurotus SPECIES ON SELECTED TROPICAL TREES SAWDUSTS

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