Influence of two Glomus species on root nodule number of cowpea (Vigna unguiculata (L) walp) varieties on Alectra vogelii inoculated soil

Abstract

Nitrogen fixation in legumes takes place in the root nodules. This research was conducted to evaluate the effect of Glomus spp. on root nodule number of four cowpea varieties grown on Alectra vogelii inoculated soil. The heat sterilized soil used for this experiment consisted of a mixture of top soil and sand in ratio 1:1 (v/v). Glomus deserticola and Glomus clarum were applied in five rates: the control without Alectra, control with Alectra, 10, 20 and 30 g/pot. A constant quantity of Alectra (3.3 g/pot) was maintained. Four cowpea seeds were planted per pot but later thinned to two seedlings per pot. Cowpea plants were sampled for root nodule number at 5, 7 and 9 WAP. The ANOVA of the three years data based on Glomus deserticola treatments showed that the control plus Alectra resulted in a significantly higher root nodule number (64.50) than the other treatments. Also, 30 g/pot Glomus clarum treatment resulted in significantly higher root nodule number (68.98). Both Glomus spp. treatments resulted in higher values in cowpea variety SAMPEA 7. From this study, Glomus clarum treatment at 30 g/pot, is recommended for increased nodulation of cowpea varieties on an Alectra vogelii infested soil.