Effect of volcanic rock dust and Fe-EDTA on the root nodule bacteria and the growth and yield of broad bean plants

The experiment was conducted during the 2018 season at the research station of the College of Agriculture and Forestry (University of Mosul, Iraq) to investigate the effect of volcanic rock dust (VRD) (0, 125, 250 g m-2) and the fertilizer chelated Iron Fe-EDTA (0, 100, 200 mg L-1) on the bacteria Rhizobium fabae, and the growth and yield of two broad bean (Vicia faba L.) varieties, Histal and Aquadulce. A randomized complete block design was used with three replicates and least significant difference (LSD) to compare means at a significance level of 0.05. Results showed that VRD 250 g m-2 obtained the highest significant mean for the following traits: leaf area index (LAI), number of branches per plant, leaf contents of chlorophyll and total iron, number of effective bacteria nodules per plant, 100-seed weight, plant yield, and percentage of protein in the seeds. On the other hand, 200 mg L-1 Fe-EDTA obtained the highest significant mean of all the traits for both varieties, except for LAI and number of branches per plant. The application of Fe-EDTA per plant had no significant effect on the leaf content of chlorophyll for both varieties and the percentage of protein in the seeds for variety Aquadulce. The interaction of VRD 250 g m-2 with 200 mg L-1 Fe-EDTA achieved the highest significant average for all the traits, except for plant height.