Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol 2, No.3, 2012 59 Growth Influence of Some Additives on the Mycelial Growth and Fruit Body Development of Pleurotus Ostreatus (Jacq. Et. Fr.) Kummer Markson, Aniedi-Abasi A.*, Madunagu, B. E., Akpan, U. D., Eshiet, E. I. Department of Botany, University of Calabar, P. M. B. 1115. Calabar, Nigeria E-mail of corresponding Author: marksoncal@yahoo.com Abstract Studies were conducted to establish the response of a wood – rotting fungus, Pleurotus ostreatus to different growth substrates (sawdust (SD), dry banana leaves (BL) and a combination of both) and additives [groundnut cake (GC) and palm kernel cake (PKC)]. Spawning (Mycelia running rate) and fruit body development (area of pileus, length of stipe and fresh weight) were assessed. Initiation of mycelial growth took place in both treated and untreated substrate samples within 7 days post inoculation (dpi). Spawn run was delayed in SD substrates treated to PKC beyond 2% and in BL substrates treated with 4% PKC and above. In BL+SD, spawn run was delayed at all levels of PKC treatments. Spawn run in the BL, BL+SD and SD controls were completed in 21, 28 and 35 days respectively, following inoculation. Primordia production occurred in all the samples within 7 days of transfer of bags to the cropping room. Treatment of substrates with additives (GC and PKC) negatively affected the performance of the substrates. Addition of 4% of the additives on BL and BL+SD substrates produced mushrooms with smaller pileus size with the smallest (13.08cm 2 ) observed on 4% PKC-treated BL substrates. Similar trends were observed in length of stipe, fresh weight and biological efficiency of the mushroom. All substrates evaluated supported production of fruit bodies for 70 days making a total of 14 flushes from the inception of cropping. Key words: Additives, Mycelial growth, fruit body production, Pleurotus ostreatus. 1. INTRODUCTION Agro-industry and the wood industry generate enormous amount of wastes yearly which are either burnt or dumped in places that constitute hazard to humans and the environment. The wise use and recycling of waste will not only minimize health hazards in the environment but can serve to generate wealth. Chang and Miles (1989) believe that using only 25% of the yearly volume of burnt cereal straws in the world for mushroom production could result in a mushroom yield of 317 million metric tons (317 billion kg) of fresh mushrooms per year. It is also the belief of Poppe (2004) that about 360 billion kg of fresh mushrooms would have been produced from the estimated 600 billion kg of dry wastes generated from agriculture (500 billion kg) and forestry (100 billion kg) within a year. Such level of mushroom production will directly translate to 60kg of mushroom per head per year which will automatically provide the 4% protein content of mushroom to them. Pleurotus ostreatus is a species of the mushrooms belonging to the group commonly called oyster mushrooms. Like many of the members of the Pleurotaceae, P. ostreatus is a primary decomposer of hardwood trees and are distributed worldwide (Kong, 2004). Of the over 70 species of Pleurotus, P. ostreatus is the most important and most commercially viable because of the compatibility of its growth requirements with the prevailing environmental factors of most regions of the world. However, different Pleurotus species require varying environmental conditions for optimal growth. For P. ostreatus, the optimum temperature range for spawn run is put at between 25-35 0 C, primordia formation occurs at temperature between 10 and 15 0 C while production of fruit bodies is accomplished between 10 to17 0 C. Kong (2004) reported that P. ostreatus requires a sharp drop in temperature usually referred to as ‘cold shock’ for primordia formation to be initiated. Co 2 requirement is put at < 1,000 and the suitable methods of cultivation ranges from shelf cultivation through cultivation in boxes, in bottles and in bags (Kong, 2004). Substrate is a major component of mushroom cultivation as it forms the nutritional source and the substratum on which the mushroom is anchored. Among the commercially viable mushrooms known, only