Effect of B, CO and MO on nodulation, growth and yield of cowpea (Vigna unguiculata)

A series of experiments was conducted to study the effect of different concentrations of micro-nutrients (i.e. "B", "CO" and "MO") on nodulation, growth and yield of two cowpea varieties, MI 35 and Bombay. In all experiments, "B" was applied as H₃BO₄, "CO" as CO(NO₃)₂ and "MO" as NH₄, MO₇O₂₄.4H₂O. Nodule number and nodule fresh weight were recorded as nodule parameters while shoot and root dry weights were recorded as growth parameters at two different stages of 30 and 50 (at physiological maturity) days after planting. Seed yield was recorded at harvest.

There was no consistent trend observed in the effect of micro-nutrients (i.e. "MO", "CO" and "B") on nodule and growth parameters of cowpea varieties, MI 35 and Bombay. Growth and nodule parameters of MI 35 cowpea showed no response to different concentrations of "MO", "CO" and "B" except at 2ppm concentration, which significantly increased the dry matter (DM) production at physiological maturity. But, variety Bombay reported different response. Application of "CO" increased nodulation and plant DM production in Bombay and the best response was observed at 6 ppm concentration. "B" application bad no beneficial effect on DM production of Bombay cowpea except at very low concentration (i.e. 2ppm), but the effect of "B" on nodulation of Bombay was beneficial upto 4ppm and it was negative with further increase of "B" concentration.