Morpho-Cultural Development of Sclerotium rolfsii, the Causative Agent of Collar Rot in Chickpea (Cicer arietinum L.) Using Grain and Host Stem Extract-Based Culture Media

Abstract

Sclerotium rolfsii Sacc., the causal agent of collar rot in chickpea (Cicer arietinum L.), is a serious soil-borne pathogen that also causes significant yield losses in several crops. This study evaluated the effect of different host grain and host stem extract-based culture media on the mycelial growth and sclerotial formation of S. rolfsii under in vitro conditions. Pure culture was inoculated on Potato Dextrose Agar (PDA), Grain Dextrose Agar (10g grain powder, 2g dextrose, and 2g agar in 100 ml), and Host Extract Dextrose Agar (10g stem part, 2g dextrose, and 2g agar in 100 ml). Significant variation in mycelial growth was observed among various grain and host extract media. The highest radial growth (90.00 mm) was observed on PDA, followed by Rice Dextrose Agar (89.25 mm) and Pearl millet Dextrose Agar (88.75 mm), while the lowest growth (59.75 mm) occurred on Chickpea Dextrose Agar. Sclerotial production was highest on Rice Dextrose Agar (288 sclerotia) and Pearl millet Dextrose Agar (282 sclerotia), whereas Chickpea Dextrose Agar supported the lowest number (174 sclerotia). In the case of plant extract dextrose agar media, including Pea Dextrose Agar, Lentil Dextrose Agar, Linseed Dextrose Agar, Mustard Dextrose Agar, and Wheat Dextrose Agar, significant growth was supported, which was comparable to that of Potato Dextrose Agar. Through examining mycelial development and sclerotial formation, media based on Corn, Pea, Rice, Sorghum, and Pearl millet grains could be suitable for the mass multiplication of this pathogen. This study also revealed that host stem extract media significantly affects the pathogen's development, and the rapid development might be due to the presence of more supportive nutrients in the host. Overall, the results showed that various grain and host extract-based media could effectively support the rapid mass multiplication of the pathogenic agent.