Alleviation of chromium toxicity in maize by Fe fortification and chromium tolerant ACC deaminase producing plant growth promoting rhizobacteria.

Chromium (Cr) is becoming a potential pollutant with the passage of time. Higher intake of Cr does not only affect the productivity of crops, but also the quality of food produced in Cr polluted soils. In the past, foliar application of Fe is widely studied regarding their potential to alleviate Cr toxicity. However, limited information is documented regarding the combined use of PGPR and foliar Fe. Therefore, the current study was conducted to screen Cr tolerant PGPR and examine effect of foliar Fe with and without Cr tolerant PGPR under Cr toxicity (50 and 100 mg kg-1) in maize (Zea mays) production. Out of 15, two Cr tolerant PGPR were screened, identified (Agrobacterium fabrum and Leclercia adecarboxylata) and inoculated with 500 μM Fe. Results confirmed that Agrobacterium fabrum + 500 μM Fe performed significantly best in improving dry weight of roots and shoot, plant height, roots and shoot length and plant leaves in maize under Cr toxicity. A significant increase in chlorophyll a (51.5%), b (55.1%) and total (32.5%) validated the effectiveness of A. fabrum + 500 μM Fe to alleviate Cr toxicity. Improvement in intake of N (64.7%), P (70.0 and 183.3%), K (53.8% and 3.40-fold) in leaves and N (25.6 and 122.2%), P (25.6 and 122.2%), K (33.3% and 97.3%) in roots of maize at Cr50 and Cr100 confirmed that combined application of A. fabrum with 500 μM Fe is a more efficacious approach for alleviation of Cr toxicity and fortification of Fe comparative to sole foliar application of 500 μM Fe.