IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 4, Issue 1 (Jul. - Aug. 2013), PP 67-70 www.iosrjournals.org www.iosrjournals.org 67 | Page Influence of p H on Growth and Sclerotia Formation of Sclerotium rolfsii Causal Agent of Foot Rot Disease of Betel Vine. B. C. Sarker 1 , S. K. Adhikary 2 , S. Sultana 3 , A. Biswas 4 and S. F. D. Azad 5 1 Lecturer, Agrotechnology Discipline, Khulna University, Khulna, 2, Professor, Agrotechnology Discipline, Khulna University, Khulna, 3 Assistant Professor, Agrotechnology Discipline, Khulna University 4 Scientific Officer, Salinity Management and Research Center, SRDI, Batiaghata, Khulna 5 PhD Student, Agrotechnology Discipline, Khulna University, Khulna Agrotechnology Discipline, Khulna University, Khulna Abstract: An experiment was conducted to evaluate the effect of different pH levels (4.5, 4.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0) on radial growth, and formation of sclerotia, weight of sclerotia of Sclerotium rolfsii on PDA (Potato Dextrose Agar) medium and fresh weight and dry weight of S. rolfsii on PDB (Potato Dextrose Broth) medium. Radial growth, fresh weight and dry weight, at different pH levels differed significantly at 1% level of significance but number of sclerotia formation and their weight did not differ. Optimum pH for radial growth, fresh weight and dry weight were found 5.0 to 6.0, 4.5 to 6.5 and 4.5 to 6.5, respectively. Key word: pH, Sclerotium rolfsii, Betel Vine Corresponding author: Sabiha Sultana, Assistant professor, Agrotechnology discipline, Khulna University, Bangladesh-9208 I. Introduction Betel vine (Paper Betle L.) is an important perennial dioecious creeper belonging to the family Piperaceae and probably a native to Malaysia. It is locally known as “Pan”. Humid and moist shaded conditions are favorable for vine growth and also favor a variety of root and foliage diseases. The recurrent of the diseases leads to complete destruction and crop failure after a few years. Sclerotium rolfsii Sacc. (Teleomorph: Corticium rolfsii Curzi) is a serious soil borne pathogenic fungus and harmful to many crops which are economically valuable in most of the tropical and sub-tropical region of the world (Aycock, 1966). It also causes diseases of other crops. It has a wide host range (Talukder, 1974) and it has been referred as an almost omnipathogenic organism (Talukder, 1974) Sclerotium rolfsii is known to be a ubiquitous pathogen that causes mild to extreme crop losses depending on environmental condition including temperature, moisture and amount of crop debris available (Aycock, 1966). The sclerotia can germinate mycelogenically forming mycelia which again form sclerotia depending upon environmental and nutrition status of the substratum (Aycock, 1966). The disease caused by Sclerotium rolfsii commonly known as seedling blight, foot rot, collar rot and Southern blight of many crops (Talukder, 1974; Chowdhury, 1946; Ahmed, 1986). Sclerotium rolfsii initiate infection usually at the collar region of susceptible host (Punja and Grogan, 198). The mycelial growth and sclerotia production of this fungus is influenced by many factors including pH, temperature, individual nutrients and volatile compounds like ethanol and C/N ratio (Devi, et al., 1999; Prithiviraj, et al., 2000; Linderman, and Gilbert, 1973). II. Materials and Methods Stems of Chachi variety of betel vine showing typical symptoms of Sclerotium rolfsii was collected from Digholia Upazila of Khulna District. The fungus was isolated following standard procedures (Dhingra and Sinclair, 1985). Diseased stems were thoroughly washed under running tap water. The stems were cut into convenient size (about 1 cm) containing black lesion where healthy and diseased tissue remains together. The cut stem pieces were first thoroughly washed by sterilized distilled water and then transferred to 0.1% sodium hypochloride (NaOCl) solution and kept there for 5 minutes. Surface sterilized stem pieces were transferred on sterilized blotting paper to remove excess NaOCl solution. The cut pieces were then placed onto sterilized water agar in glass petriplates with the help of sterilized forceps and incubated in room temperature (30±2) 0 C until mycelial formation. All the works were done in a laminar air flow cabinet. Fungal isolates was identified based on the characteristics of hyphae and sclerotia (Lilly and Barnett, 1951) Pathogenicity test was done on excised stem of betel vine. Healthy stems of betel vine were cut into pieces (about 1 inch.) and surface sterilized with 70% ethanol for 10 seconds. Stem pieces were injured softly by flame sterilized pointed needles and then placed onto sterilized water agar. Advance hyphae were cut from 30