The use of rhizobium and mycorrhizae in soil containing rhizobiophage to improve growth and nodulation of cowpea

Abstract

ABSTRACT: The interaction between leguminous plants and rhizosphere microorganisms is essential because it can either enhance or inhibit the beneficial effects of individual species. Phages are one of the biotic factors with a negative impact on the beneficial bacteria in soil rhizosphere. In the current study, phage showed lytic activity against Bradyrhizobium sp. Vigna (tal16) with an icosahedral head at a 43.44 nm diameter and a long non–contractile tail, measuring 99.85 nm. This phage belongs to the Siphoviridae family, found in the Met El–Ez area of Dakalia Governorate in Egypt. The results revealed that the presence of phage in soil affected nodulation and growth parameters. Mycorrhizal inoculation aggravated the negative effects of this phage. Cowpea grown in soil containing phage VB_BrV_SD4 showed a reduction in the nodule number, nitrogenase activity, and total N of 40–50 %; however, mycorrhizal inoculation augmented this negative effect with a reduction percentage to 20–28 %. Mycorrhizal inoculation also improved total chlorophyll, carotenoids, legume amount, and the seed protein content.

Keywords

• symbiosis
• interaction
• bacteriophage
• agricultural microorganisms
• nitrogen fixation