Influence of the co-inoculation Azospirillum brasilense and Rhizobium meliloti plus 2,4-D on grain yield and N, P, K content of Triticum aestivum (cv. Baccros and Mahdavi).

Abstract

4 Abstract: Co-inoculation with symbiotic microorganisms to create a successful system of biological nitrogen fixation in a non-legumes crop can lead to many profits for plant. The aim of this work was to evaluate the single and co-inoculation effects of Azospirillum basilense (native or Sp7) and Rhizobium meliloti (native or DSMZ 30135) plus 2,4-D on grain yield and the total N, P and K content of the grain. The results indicated that co-inoculation of wheat seeds with A. brasilense and R. meliloti had positive and significant effects on the grain yield and N, P and K content of the wheat grains in compared to either single inoculation or control plants. In overall, the average grain yield was increased to 53.8% of co-inoculation plants with a mixture of A. brasilense and R. meliloti compared to the control plants. This was due to increasing number of grains (26%) and grain weight per plant (22%) in co-inoculated plants. The results showed that single inoculation with Azospirillum produced significantly higher grain yield by 29% and the grains contain more N (22.8%), P (59.5%) and K (34%) compared to the control plants. Simultaneously, co-inoculation increased the mentioned parameters by 53.8, 52, 114 and 82%, respectively compared to the control Therefore, the effect of either the single or dual inoculation of wheat with A. brasilense and R. meliloti could result higher grain yield with better quality. However the effect of single and/or co-inoculation on plant growth parameters varies depending on the strain of A. brasilense (Sp7 and native), wheat cultivars and selected of co-inoculants (type of mixed strains). The highest grain yield and also N, P and K in grain were observed in combination of the local strains (native A. brasilense and native R. meliloti) when concentration of 10 cfu ml and 10 cfu ml 71 3 1 were used respectively for the strains plus 2 ppm of 2,4-D.