Bacterial inoculations mitigate different forms of iron (Fe) stress and enhance nutrient uptake in rice seedlings (Oryza sativa L.)
Sapna Chandwani, Sonal Manik Chavan, Dhiraj Paul, Natarajan Amaresan
Abstract
Iron (Fe) is an essential micronutrient required by plants for various physiological processes. However, the accumulation of excessive Fe affects plant growth and agricultural productivity. In the present study, 250 iron tolerant bacteria (ITB) were isolated from 25 soil samples, screened for plant growth-promoting properties and identified based on 16S rRNA gene sequencing. A pot study experiment using rice plants amended with three forms of Fe (FeSO4, FeCl3 and [Fe(NH4)2(SO4)2]) revealed the enhancement of root and shoot length ranged from 42.67%–177.35% and 88.10%–119.19% in FeSO4 amended soil, 64.25%–161.54% and 81.07%–124.46% in FeCl3 soil and 66.65%–159.60% and 69.04%–119.70% in Fe(NH4)2(SO4)2 compared to control and non-inoculated plants. Further, the ITB inoculated seedling showed enhanced N uptake 0-4 fold and P content 1-2 fold compared to control. Similar enhancement of Fe mobilization was also observed for soils amended with FeSO4 (2-4 fold in the root and 2-3.5 in the shoot), FeCl3 (2.5-6 and 2-5 fold) and Fe(NH4)2(SO4)2 (2-5 and 0-2 fold). The estimation of and Fe2＋ and Fe3＋ revealed that Fe2+ uptake in the ITB inoculated roots and shoots of rice plant ranged to 4-7.85 ppm compared to control (0.55-18.36 ppm). Whereas the Fe3＋ uptake was ranged to 20.52-58.15 ppm in roots and 0.70-47.61 ppm in shoots compared to control (0.67-1.95 and 0.25-3.12 ppm). Enhanced chlorophyll contents (p ≤ 0.05) was also observed in the inoculated plants. The present study demonstrated that the inoculation of ITB improved the sequestration of Fe from the soils and mitigated the Fe stress in rice plants.