Effect of iron oxid nanoparticle on the growth and physiology of inoculated alfalfa (Medicago sativa L.) with Rhizobium meliloti

The aim of this study is to evaluate the interaction of bacterial inoculation and iron treatment (nano and Fe-chelate) on physiological traits of alfalfa.

  In this study, effects of inoculation with standard Rhizobium meliloti, effects of different levels of iron (Fe-chelate, 0, 5, 10, 20 and 25 μM Fe2O3 nanoparticles) and the interaction of bacterial inoculation and iron treatment were investigated on alfalfa in a factorial experiment in completely randomized design with three replications for 45 days. The measured traits were growth indexes, photosynthetic pigments, protein, proline, antioxidants activity, DPPH(diphenyl-picryl-hydrazyl)-radical scavenging activity percent and elements content.

Rhizobium incoculation alone showed beneficial effects on the alfalfa growth and was caused increasing in growth parameters, pigmants, protein content, potassium and phosphours uptake. However inoculation did not effect on the proline and antioxidant content. Iron treatment had a positive effect on the growth parameters, pigmants, protein content and elemant uptake. Highest values of growth parameters was observed 25μM Fe2O3 nanoparticles. The highest values of proline and antioxidants activity were measured in control (0μM nanoparticles). Since this concentration is considered a stress for alfalfa. Negative effects of  0μM nanoparticles decreased in inoculated alfalfa plants with R. meliloti. Indeed rhizobium causes increasing in inoculated plant resistant by reducing stressful conditions.

Rhizobium-alfalfa symbiosis plus iron nanofertilizer can cause increasing in plant resistance to stress, in addition to increase growth of plant. The highest amount of growth parameters, pigmants and protein content was measured in inoculated plant  with Rhizobium meliloti and 10μM nanoparticles.