Impact of Species-Specific Plant Growth-Promoting Rhizobacteria (PGPR) on Maize (Zea mays) Phenotypic and Biochemical Diversity

Abstract

Maize (Zea mays) is a vital cereal crop used as a staple diet in many countries. In contemporary farming practises, inoculation with plant-growth-promoting rhizobacteria (PGPR) can be promoted as a sustainable alternative to chemical fertilizers and pesticides in cereal crops including maize. For experimental verification of the above-mentioned hypothesis, four PGPR inoculants Pseudomonas fluorescens, P. putida, Azospirillum lipoferum and Bacillus subtilis were applied to three maize genotypes (AXE*, PMH1 and PMH10) and their effects were studied by measurement of various morphological and biochemical paramters. Substantial increase in the amount of chlorophyll a (45%), chlorophyll b (100%), total chlorophyll (95%), nitrate reductase (22%), superoxide dismutase (52%), protein content (16%), methionine content (31.8%), grain protein content (69%) were recorded over the control (non-treated or mock) plants. Morphological parameters also exhibited an increase in leaf number (53%), fresh weight (41%) and dry weight (62%) in test plants. Comparable outcome was observed for whole cob weight showing an increase of 42%, cob weight (60%), hundred-grain weight (25.9%), maize grain yield m-2 (18%) and yield ha-1 (18%) over the control. This study highlights the efficacy of the aforementioned four PGPR species as the most effective for maize crops. Bacillus subtilis and Azospirillum lipoferum may be considered species-specific PGPRs due to their superior performance compared to other strains. The considerable growth-promoting advantages observed in maize plants treated with bacterial inoculation indicated that PGPRs have the potential to be employed as sustainable solutions in maize production.