Effects of different inoculum on the growth and nitrogen fixing ability of cowpea.

Haider J.; Islam T.; Mohiuddin M.; Yamada Y.

Effects of different inoculum on the growth and nitrogen fixing ability of cowpea.

1989

Haider J. | Islam T. | Mohiuddin M. | Yamada Y.

Three rhizobia strains from groundnut (GN), chickpea (CP) and soybean (SB) were maintained in peat media. Eight treatments constituted of 2 cowpea varieties and 3 rhizobial strains (GN, CP and SB) with a control (non-inoculated). Control plants were supplied with 18 ppm N-containing nutrient solution, whereas inoculated plants were supplied with nutrient solution (without N) every day. Nodulation study conducted at 30 days after emergence (DAE) identified that up to 10.0 and 4.8 times increased nodulation against the control (-IN) occurred by var. SSD625 and IT82E60 respectively. Nodulation by CP and SB treatments did not differ significantly from the control. Nodule dry weight showed increasing tendency by all inoculum and both varieties. GN inoculation had significantly highest nodule dry weight (464 and 456% increase by SSD625 and IT82E60 respectively) as compared to the control. Nitrogenase activity of nodule bacteria measured by Gas Chromatograph showed that the highest activity was performed by GN inoculum in both varieties. The activity increment rate was highest at 30 DAE for GN inoculum. By GN and CP inoculum treatment the nitrogenase activity decreased after 60 DAE, but SB inoculation showed and increasing tendency at this stage.

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