Abstract

Glycine max – Rhizobium interaction is a well known symbiotic association occurring in nature and responsible for biological nitrogen fixation. Thiram a well-known fungicide has been in practice as seed dressing in order to prevent fungal colonization. In the present study the effect of various thiram concentrations is investigated. Thiram concentration beyond 500 μg/ml was observed to be highly toxic with respect to plant growth factors and rhizobial infection to the G. max. The nodulation, nodule dry weight, nitrogenase activity were observed to be maximum at 100 μg/ml of thiram. The study is useful in determining the threshold concentration of fungicide for soybean seed dressing for effective nitrogen fixation and crop yield.

Key words: Ascorbic acid, chlorophyll content, Glycine max, nodulation, nodule dry weight, nitrogenase activity, protein content, thiram.