Effect of rhizobial inoculation on nodulation and plant growth of faba bean in Tunisian farmer’s field test

Abstract

Osmotic constraints, nutrient deficiencies, especially phosphorus, and the lack of efficient strains of rhizobia in Mediterranean soils are major factors limiting symbiotic nitrogen fixation and yield in faba bean (Vicia faba L.var. minor). In order to improve faba bean plant growth and nitrogen uptake in a multi-local field test, experiments were carried out in 2012/2013 in twelve farmer’s fields in different environments with the commercial cultivar Bachar of faba bean and was inoculated with a local rhizobial strain Mat.11. Nodulation, plant growth, efficiency in use of the rhizobial symbiosis, nitrogen accumulation and the effect of soil phosphorus (P) availability on plant growth analysis were measured in inoculated and non inoculated treatments. The results indicate a large spatial variation in nodulation and plant growth with the rhizobial strain inoculated under field conditions. Moreover, we noticed a correlation (r² = 0.45) between the rhizosphere P availability and efficiency in use of the rhizobial strain. In many sites, the inoculation with Mat.11 increased significantly not only nodule number and biomass but also the total plant nitrogen uptake comparing to without inoculation treatment. It is concluded that faba bean inoculation improve significantly nodulation and plant growth. Further investigations should address the variation SNF among local genotypes and the symbiosis mechanisms to stabilize the legume production in soils with low fertilizer input.

Keywords: correlation, nitrogen, nodulation, phosphorus, Tunisia.