Effect of Plant Beneficial Rhizobacteria on Growth and Yield of Wheat (Triticum aestivum L.) Grown in a Sandy Clay Loam Soil under Pot Experiment

Abstract

Excessive and injudicious application of agrochemicals to optimize crop production has shown detrimental effects on microbial composition and function, soil-plant ecosystems, and human health via food chain. The microbiological strategies (phosphorus solubilization and ammonium production etc.), reduce the chemical dependency and mitigate environmental and human health risks. This study aimed to isolate and characterize plant beneficial bacteria from maize rhizospheres and asses their impact on wheat performance in pot trials. Cultures were characterized by morphological and biochemical assays. From these, two optimal cultures designated BSK1 and PS1, were selected for further investigation into their plant-growth promoting traits. The bacterial strains have ability to produce indole-3-acetic acid (IAA), siderophore, hydrogen cyanogenic and ammonium compounds along with phosphorus solubilization. Meanwhile, BSK1 demonstrated superior production levels of Indole-3-acetic acid (IAA), (203.61±2.08 μg ml-1), phosphate solubilization (15 mm) and siderophores (17 mm). Furthermore, both cultures exhibited positive qualitative traits for hydrogen cyanogenic and ammonium compounds. Later identified by 16S rRNA gene sequencing as B. subtilis (BSK1) and P. fluorescens (PS1). Respectively. Subsequently, in a two-year trial, the co-inoculation of the wheat plants by B. subtilis with P. fluorescens maximally enhanced the whole plant biomass, total chlorophyll content (7.9 mg/g), grain yields (33.5 g/plant), and protein content (96.2 mg/g) at harvest. A heavy bacterial colonization onto the root rhizosphere was revealed under scanning electron microscopy (SEM) image which was significantly dense for mixed cultures of B. subtilis with P. fluorescens. The results suggest that B. subtilis and P. fluorescens expressing multiple plant growth-promoting activity can be used to produce composite bioinoculants for enhancing wheat production while reducing the use of fertilizers.