*Present address: Soil Chemist, Department of Soils, Haryana Agricultural University, Hissar-125004
The study was conducted on the growth of Anabaena doliolum in solution culture under controlled conditions using various levels of copper and molybdenum and different sources of nitrogen. Interactions between copper and sources of nitrogen were found significant on the growth of A, doliolum cultivated in Fogg's medium. Increasing concentrations of copper (0.0025–0,01 ppm) stimulated growth when nitrogen was available as nitrate and molecular nitrogen but inhibited growth when ammonium was the nitrogen source.
