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Soil Microbiologists have been concentrating on manipulation of rhizosphere microbes in cereals, but many researchers have reported that rhizobia can act as plant growth promoting rhizobacteria (PGPR). Rhizobium species impacted the crop ontogeny by root / endophytic colonization, producing phytohormones, efficient nutrient use and nutrient solubilization / mineralization. Field studies were performed at Soil Bacteriology Section and Soil Chemistry Section, Faisalabad to assess the comparative potential of Rhizobium species for promoting the growth, yield of wheat and rice. Auxin biosynthesis potential of isolates of Rhizobium species (mung (Vigna radiata), berseem (Trifolium alexandrinum), chickpea (Cicer arietinum), lentil (Lens culinaris) and peanut (Arachis hypogaea)) was determined and isolates of each species having higher values were used for field experiments. Assay for root / shoot elongation, root colonization in plates were carried out under controlled conditions. The rhizosphere soil of wheat and rice were assayed for the Indole Acedic Acid (IAA) content 15 and 30 days after germination / transplanting, respectively. Results revealed that significant increase was observed in the yield parameters of wheat and rice. Highest wheat grains were produced i.e., 4917 kg ha-1 with Rhizobium sp of mungbean (Mb3) followed by 4823 with Rhizobium sp of berseem (Br3) than control i.e., 4500 kg ha-1. Similarly, the maximum paddy yield i.e., 4667 kg ha-1 with Rhizobium sp of mungbean (Mb3) followed by 4625 Rhizobium sp of berseem (Br3) inoculation was obtained as compared to control i.e., 4208 kg ha-1. Other physical parameters of wheat and rice also showed positive response to inoculation and have elevated levels of IAA in the rhizosphere of inoculated treatments. Results clearly demonstrated that Rhizobium species increased the yield of rice and wheat.

Iron (Fe), being an essential micronutrient, is necessary for human health and to maintain the integrity and development of the plant. In Fe-limiting conditions, plants and plant growth-promoting rhizobacterial (PGPR) have a siderophore production mechanism. Inoculation with seed soaking of such siderophore-producing bacteria can be a cost-effective biofortification technique. The current study includes the collection of rhizobacterial isolates from wheat, maize, sorghum, millet, and maize rhizosphere soil of Rawalpindi and Sargodha divisions. The screening of bacterial isolates for siderophore production through CAS-shuttle assay (quantitative) and CAS-agar (qualitative) was done. Isolates were further characterized for Fe and phosphorus solubilization, indole acidic acid (IAA) equivalents, and organic acid production. The growth chamber and field study was planned to evaluate the effectiveness of these isolates on the growth and yield parameters of wheat. Total bacterial isolates were 50, out of which 15 isolates were found significantly positive for the production of siderophore and solubilizing of nutrients. The (SPS10) produced a comparatively high percentage of 46.2 % siderophore units, as shown by results between positive isolates. Out of 15 positive, 7 isolates significantly improved root/shoot growth over control in the growth chamber study. Inoculation with siderophore-producing bacteria showed a significant increase in plant height, grain yield, spike length, grain weight, no. of tillers plant -1 , and wheat quality in a field trial. The results from the current study proposed that in the plant, rhizobacteria can also play a beneficial role in nutrient translocation to plants efficiently and nutrients uptake from the soil insoluble form.

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