Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

Abstract

The goal of this study was first to assess the dynamics of the bacterial community during a growing season in three Indian rain-fed wheat fields which differ mainly through their fertilizer management and yield and then to study the effects of PGPR/AMF bio-inoculations on the bacterial community structure and wheat growth. The bacterial community structure of the rhizosphere soil (RS) and the rhizoplane/endorhizosphere (RE) was determined by PCR-denaturing gradient gel electrophoresis. Seed treatments consisted of consortia of two PGPR strains alone or combined with AMF or AMF alone. The PGPR strains were Pseudomonas spp. which included some or all of the following plant growth promoting properties: phosphate solubilisation and production of indole-3-acetic acid, siderophores, 1-aminocyclopropane-1-carboxylate deaminase and diacetyl-phloroglucinol. The mycorrhizal inoculum was an indigenous AMF consortium isolated from the field with the lowest level of fertilization and yield. Variation partitioning analysis of the DGGE data indicated a predominant effect of the wheat growth stage (30.4% of the variance, PZ0.001) over the type of field (9.0%, PZ0.027) on the bacterial community structure in the RE. The impact of plant age in the RS was less than in the RE and the bacterial community structure of the field with the highest input of fertilization was very different from the low input fields. The bio-inoculants induced a significant modification in the bacterial community structure. In the RS, the bacterial consortia explained 28.3% (PZ0.001) and the presence of AMF 10.6% (PZ0.02) of the variance and the same trend was observed in the RE. Plant yield or grain quality was either increased or remained unaffected. For example, protein content was significantly higher in the treated plants' grain compared to the control plants; maximum values were obtained when the PGPR were co-inoculated with the AMF. The percentage of root colonization by AMF was significantly higher in the treatments containing a mycorrhizal inoculum than in the untreated control and remained unaffected by the PGPR treatments. In conclusion, the wheat rhizobacterial community structure is highly dynamic and influenced by different factors such as the plant's age, the fertilizer input and the type of bio-inoculant. In addition, there is a distance-related effect of the root on the bacterial community. Finally, a combined bio-inoculation of diacetyl-phloroglucinol producing PGPR strains and AMF can synergistically improve the nutritional quality of the grain without negatively affecting mycorrhizal growth.

The Role of Soil Beneficial Bacteria in Wheat Production: A Review

“…Similarly, increased nutrient concentrations in wheat due to inoculation were reported in Refs. [5,118,[162][163][164][165]. It is pointed out by Mäder et al that microbial inoculants have been shown to be a valid option for sustainable high quality wheat production in low-input areas, promising to improve the nutritional status and health of the rural population [163].…”

“…Wheat rhizobacterial community structure is highly dynamic and influenced by different factors such as wheat cultivar line ages, plant's age, growth stage, distance from the soil to the root, root exudation pattern, multiple soil properties and agronomic practises [162,188,189].…”

“…and an indigenous AMF to study their effect on the bacterial community structure and wheat growth [162].…”

Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice

“…Pseudomonas strains LHRE62 and HHRE81 were recovered from wheat rhizosphere of rice-wheat cropping system, under ISCB project [7][8][9]. They were tentatively identifi ed to respectively P. jessenii and P. synxantha (>99% SSUrDNA homology) [8].…”

The Evaluation of Organic and Chemical Fertilizers on Growth Characteristics and Essential Oil of Sage (Salvia Officinalis L.) Under Water Stress

“…Vermicompost rich source of macronutrients, micronutrients, vitamins, enzymes and hormones of plant growth promoters. Therefore, the use of vermicompost in sustainable agriculture, in addition to increasing population and activity of beneficial soil microorganisms, causes the rapid growth of medicinal plants [1].The uses of bacteria (Azotobacter, Azospirillum and Pseudomonas) as a biofertilizer have causes increasing the efficiency of nitrogen and phosphorus fertilizers and improving the growth of several crops [2]. Drought stress is one of the most important environmental stresses that affect the growth and yield of plants [3].…”