5.2.49
BIOLOGICAL CONTROL OF SEED AND SEEDLING ROT COMPLEX OF SOYBEAN

AN MUKHOPADHYAY1 and R PANT2

1Assam Agricultural University, Jorhat-785013, Assam , India; 2GB Pant University of Agriculture and Technology, Pantnagar-263145, UP, India

Background and objectives
Seed and seedlings rot complex of soybean are major problems in successful establishment of soybean crop in many parts of India. Several pathogens belonging to the genera of Pythium, Phytophthora, Rhizoctonia, Scierotium and Fusarium are responsible for the seed and seedlings rots. Management of the problem is difficult because of involvement of a large number of pathogens belonging to different groups.

Results and conclusion
The present investigation was undertaken to explore the possibility of management of the problem by biological seed treatment with Gliocladium virens and Trichoderma harzianum. Soybean seeds were treated with powdered preparation [1] of the above two antagonists. Such treatment resulted in excellent control of the seed and seedling rot over control. The mechanism of action was determined by light microscopy of the seed and seedlings [2] at different stages after biological seed treatment. The antagonists colonised the seed coat, radicle and plumule within 48 h of planting and protected the seed and seedlings from infection by the pathogens. The protection continued for the entire crop season. Biological seed treatment of soybean by G. virens and T. harzianum has tremendous potential for management of seed and seedling rot of soybean under large scale commercial cultivation.

References
1. Mukhopadhyay AN, 1994. Indian Phytopathology 47, 119-126.
2. Mukhopadhyay AN, 1995. In Proceedings of Fifth International Trichoderma/Gliociadium Workshop, held at USDA, Beltsville, USA, April 18-20 1995.