Journal of Food, Agriculture & Environment, Vol.8 (1), January 2010 135 Evaluation of grafting techniques and a new rootstock for resistance of pepper (Capsicum annuum L.) towards Phytophthora nicotianae Mahmoud M’Hamdi 1, 2 , Naima Boughalleb 3 , Nada Ouhaibi 3 , Neji Tarchoun 3 , Mounira Souli 3 and Lassaad Belbahri 4 * 1 Department of Horticultural Sciences, Higher Institute of Agronomy of Chott Mariem, 4042, Sousse, Tunisia. 2 Unité des Cultures Maraîchères et Florales, Institut National Agronomique de Tunisie, 1002, Avenue Charles Nicolle, Tunis, Tunisie. 3 Department of Biological Sciences and Plant Protection, Higher Institute of Agronomy of Chott Mariem, 4042, Sousse, Tunisia. 4 Agronomy Department, Research Institute Earth Nature and Landscape, School of Engineering of Lullier, 150 Route de Presinge, 1254 Jussy, Switzerland. *e-mail:lassaad.belbahri@hesge.ch Received 6 October 2009, accepted 2 January 2010. Abstract Pepper wilting and root rot disease have been observed in Tunisia for many years. This disease causes severe losses for pepper production both in fields and greenhouses in the main crop cultivated areas of pepper production. The causative agent of the syndrome belongs to the genus Phytophthora and has been identified as Phytophthora nicotianae. Being a soil-borne pathogen, effective disease control methods are limited apart from soil disinfestations by fumigation with methyl bromide and disinfection of internal space of greenhouses with a formaldehyde solution. With the general banning of methylbromide from Europe and countries exporting legumes to the European market, alternative measures for disease management are urgently required. In this study the efficacy of grafting commercial pepper cultivars (Starter and Torero) onto a new rootstock (Brutus) was examined in growth chamber and greenhouse experiments. Hole insertion grafting is shown in this study to be the grafting technique of choice for pepper and validates the general trend that grafting could be used as an alternative control method of soil-borne pathogens such as Phytophthora nicotianae. Key words: Grafting, rootstock, disease resistance, Capsicum annuum L., Phytophthora nicotianae. www.world-food.net Journal of Food, Agriculture & Environment Vol.8 (1) : 135-139. 2009 WFL Publisher Science and Technology Meri-Rastilantie 3 B, FI-00980 Helsinki, Finland e-mail: info@world-food.net Introduction Pepper (Capsicum annuum L.) is an important vegetable crop in Tunisia and many other countries. It is grown across all the country and mainly in the plains of the centre and the east costal areas 1 . The extension of pepper culture is limited by technical, climatic and phytosanitary concerns 2-6 . Many diseases affecting present day pepper culture are due to intensification of culture practices without the basic perception of intricate balance between host, pathogen and environment. Increasing agricultural imports of new and highly productive varieties benefits pepper culture in Tunisia, but shipments transported two harmful foreign diseases, Verticillium wilt and Phytophthora blight, resulting in severe losses both in fields and greenhouses pepper production areas. Phytophthora nicotianae Breda de Haan has also been confirmed as the agent responsible for pepper blight in Tunisia 7, 8 . Similarly to what happens with most of the diseases of Phytophthora etiology, the control of pepper blight is generally inefficient, especially the chemical control. The use of resistant or tolerant varieties is an inexpensive and easy means of controlling plant diseases in crops where such varieties are available. However, developing resistant varieties is still a complicated task and evidence is constantly accumulating of pathogen adaptation to resistant varieties 9-12 . Emerging new production technologies such as grafting are promising. This technology is intended to reduce soil-borne pathogens incidence, boost plant growth and development and increase tolerance to diverse biotic stresses 13,14 . This work was intended to broaden the choice of available rootstocks by testing the new pepper rootstock ‘Brutus’ and to evaluate disease resistance of grafted varieties Starter and Torero towards three isolates of Phytophthora nicotianae (Ph1, Ph2 and Ph3). Materials and Methods Plant material and growth conditions: Two pepper cultivars Starter and Torero and the rootstock ‘Brutus’ have been used during this study conducted at the Higher Institute of Agronomy of Chott Mariem, Tunisia, during 2007-2008. Embedded seeds (120) of the different cultivars and the rootstock were pre- germinated in between two sheets of distilled water moistened filter paper in a Petri dish at 28°C for four days. Rootstock seeds were pre-germinated 7 days before the pepper cultivar seeds. Rootstock advanced seeds were then transferred to 10 cm diameter pots, while cultivars advanced seeds were transferred to seedling trays filled with peat (pH 5.8-6.8). Plants were grown under a greenhouse tunnel with daily irrigation. Grafting techniques: Three grafting techniques were used in this study. Approach, cleft and hole insertion grafting were performed one month after sowing pepper cultivars (5 to 6 true