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Brazilian Journal of Microbiology (2011) 42: 508-513 ISSN 1517-8382

INOCULATION OF TOMATO SEEDLINGS WITH TRICHODERMA HARZIANUM AND ARBUSCULAR MYCORRHIZAL FUNGI AND THEIR EFFECT ON GROWTH AND CONTROL OF WILT IN TOMATO SEEDLINGS Margaret W. Mwangi1*; Ethel O. Monda1; Sheila A. Okoth2; Joyce M. Jefwa3
1

Department of Plant and Microbial Sciences, School of Pure and Applied Sciences, KenyattaUniversity, Box 43844–00100 Kenya; 3CIAT-Nairobi TSBF. Off UN Avenue Gigiri P.O.Box 823- 001621 Nairobi. Kenya.
Submitted: November 10, 2009; Returned to authors for corrections: December 14, 2009; Approved: November 04, 2010.

Nairobi, Kenya; 2Department of Botany, School of Biological Sciences, University of Nairobi, Box 30197-001000 Nairobi.

ABSTRACT A green house study was conducted toinvestigate the ability of an isolate of Trichoderma harzianum (P52) and arbuscular mycorrhizal fungi (AMF) in enhancing growth and control of a wilt pathogen caused by Fusarium oxysporum f. sp. lycopersici in tomato seedlings. The plants were grown in plastic pots filled with sterilized soils. There were four treatments applied as follows; P52, AMF, AMF + P52 and a control. A completely randomizeddesign was used and growth measurements and disease assessment taken after 3, 6 and 9 weeks. Treatments that significantly (P < 0.05) enhanced heights and root dry weights were P52, AMF and a treatment with a combination of both P52 and AMF when compared the control. The treatment with both P52 and AMF significantly (P < 0.05) enhanced all growth parameters (heights; shoot and root dry weight)investigated compared to the control. Disease severity was generally lower in tomato plants grown with isolate P52 and AMF fungi either individually or when combined together, though the effect was not statistically significant (P 0.05). A treatment combination of P52 + AMF had less trend of severity as compared to each individual fungus. T. harzianum and AMF can be used to enhance growth in tomatoseedlings. Key words: Arbuscular mycorrhizal Fungi (AMF), Trichoderma harzianum (P52), Disease severity INTRODUCTION Tomatoes are one of the most widely cultivated vegetable crops in Africa. Its fruit is rich in vitamins and is therefore used in salads, cooked as a vegetable or made into tomato paste and tomato sauce. Tomato yields in smallholder cropping systems are generally far below thepotential of the crop, due to low quality seeds, poor crop husbandry and pests and diseases (23). In Kenya there was a decrease in total area planted with tomatoes and production of tomatoes between the years 20052006 (15). Total area in hectares reduced from 20,743 to 19,541, production from 337,447 to 334,478 metric tonnes and

*Corresponding Author. Mailing address: Department of Plant andMicrobial Sciences, School of Pure and Applied Sciences, Kenyatta University, P.O. Box 43844–00100, Nairobi, Kenya.; E-mail: wanjirumargie@yahoo.com

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Mwangi, M.W. et al.

T. harzianum and arbuscular mycorrhizal fungi

value from 5.6 billion shillings to 4.9 billion shillings. The major constraints that caused this decline were high prices of inputs, poor crop management practices,transportation, marketing, diseases and pests. Tomato plants are affected by several diseases, including Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (sacc.) Snyder and Hansen. This is a destructive disease of tomato worldwide (14). Methods used to control vascular wilt are either not very efficient or are difficult to apply. The best way to control the disease is by selecting resistantvarieties of tomatoes. Although commercial varieties of tomato resistant to F. oxysporum f. sp.lycopersici races 1 and 2 are available, additional pathogenic strains and race 3 of the pathogen has been reported in several countries (2). For this reason, alternative methods of controlling the disease have to be explored inclusive of biological control methods. Adding biocontrol agents directly to...