Population dynamics and identification of efficient strains of Azospirillum in maize ecosystems of Bihar (India)

Abstract

Information on inoculum load and diversity of native microbial community is an important prerequisite for crop management of microbial origin. Azospirillum has a proven role in benefiting the maize (Zea mays) crop in terms of nutrient (nitrogen) supply as well as plant growth enhancement. Bihar state has highest average national maize productivity although fertilizer consumption is minimum, indicating richness of Azospirillum both in terms of population and diversity in soils. An experiment was planned to generate basic information on Azospirillum population variation in maize soils under different agricultural practices and soil types of Bihar, to identify suitable agricultural practices supporting the target microorganism and efficient Azospirillum strain(s). No tillage, growing traditional maize cultivar, land use history (diara soil having history of maize cultivation), soil organic carbon (>1%) and intercrop with oat supported prevalence of Azospirillum in maize rhizosphere. Native Azospirillum population varied from 1 million to 1 billion/g soil under diverse agricultural practices and soil types. Such richness, however, does not necessarily mean that artificial inoculation of Azospirillum is not required in Bihar soils as 92% of Azospirillum isolates (50 isolates) were poor in nitrogen-fixing ability and 88% were poor on IAA production. Efficient strains of Azospirillum based on growth (three), acetylene reduction assay (three), IAA production (three), broad range of pH (two) and temperature tolerance were identified. The findings suggested that maize crop in Bihar should be inoculated in universal mode rather than site-specific mode.

Cumulative Impact of Herbicides and Tillage in Conservation Agriculture on Soil Microbiome, Fungal Diversity and Crop Productivity

“…The observations in this experiment on rhizosphere microbial and rhizoplane fungal population clearly indicated that the counts increased significantly with the crop advancement ascribed to the progressive mineralization of the litter fall from the crops, root exudates and added crop residues and enhanced availability of organic substrates for provision of food and increase in the population of microbes. Our results concur with that of Verma et al [60] and Bashan et al [61] who observed an increased trend in the preponderance of Azot and Azosp strains with an increase in organic carbon level from 0.2-1.0%.…”

The effect of beneficial microorganism as biofertilizer application in hydroponic-grown tomato

“…The benefits of plants inoculated with Azospirillum was not only associated to its capacity to fix atmospheric N2, but also to its ability to synthesize phytohormones, indole-3-acetic acid (Fukami et al, 2018). In the soil, the distinct impact on preponderance of Azospirillum in maize rhizosphere varied, contributing to distinct physio-chemical factors and history of land use patterns (Verma et al, 2011). The application of biofertilizer proliferated the population of PSB compared to the treatment without biofertilizer.…”

Endophytic Azospirillum for enhancement of growth and yield of wheat

“…The ability to form plant hormones has been postulated as a major property of PGPR in general and specifically, by the species of Azospirillum (Tsavkelova et al 2006). Verma et al (2011) showed that 88% of the evaluated Azospirillum strains (50 isolates) from maize soils were poor in IAA production indicating a substantial variability among Azospirillum strains for IAA production. The variation in the ability of plant growth promoting bacteria to produce IAA had also been observed earlier (Zahir et al 2000;Majeed et al 2015).…”