Nitrogen fixing ability of 13 genotypes of Mucuna pruriens using

acetylene reduction assay

B Mamatha^l, T N Shivananda² and R Siddaramappa^l

¹University of Agricultural Sciences, Bangalore 560 065

²lndian Institute of Horticultural Research, Bangalore 560 089

ABSTRACT

Mucuna pruriens is a high value medicinal crop grown for its seed to extract L-dopa used against Parkinson disease. The roots bear nodules and fix atmospheric nitrogen enriching the soil fertility. Pot culture and field studies were conducted using 13 genotypes to evaluate nitrogen fixing ability and L-dopa content in seeds during 2002-03 at Indian Institute of Horticultural Research, Bangalore (13° 58¹ N 78° E ). The crop was grown on red clay loam soils having pH 5.50 and low in soil organic matter. Nitrogen fixing ability was assessed using acetylene reduction assay (ARA). Results suggested that IIHR-MP-02 fixed the highest (208.9 ARA) amounts of nitrogen and the least in IIHR-MP-17 (67.8 ARA). Flowering stage recorded higher values compared at harvest. Nodule number and nodule biomass was the highest in IIHR-MP-02. Further L-dopa content in seeds was the highest (6.61%) in IIHR-MP-02 and the least in IIHR-MP-17. These results suggest that there is a positive relationship between nitrogen fixation, nodule number, nodule biomass and even active principle (L-dopa) content in seeds.

Key words: L-dopa, Mucuna pruriens, N fixation