Native arbuscular mycorrhizal fungi improve growth, biomass yield, and phosphorus nutrition of sorghum in saline and sodic soils of the semi-arid region

Exploiting symbiotic plant-microbe interactions with arbuscular mycorrhizal fungi (AMF) adapted to hostile soil can be a promising approach for enhancing crop productivity and tolerance to salinity and sodicity-related stresses in salt-affected agroecosystems. This study was conducted to characterize the native mycorrhizal ecotype and its responsiveness to sorghum in saline and sodic soils under controlled conditions. The AMF spore density in sodic soil under the rice-wheat cropping system was greater than in the sorghum-based systems. The spore density was greater under sodic compared to saline soils. The sequence of the amplified fungal ribosomal DNA of the 18 S region of the isolated culture from the rice-wheat system under sodic soil conditions showed the Funneliformis mosseae and Funneliformis geosporum as the dominant AMF species. The colonization and arbuscular abundance of Funneliformis sps. inoculated sorghum was greater for sodic and normal soil, respectively. Plant height and fresh and dry biomass of AMF inoculated plants were greater in normal soil followed by sodic and saline soils. Sodic soil showed a greater increase in root-to-shoot ratio compared to saline soils. The P content, P uptake, and K+/ Na+ were greater in AMF inoculated soils. The increase in Olsen's-P in AMF inoculated soils was in the order of normal > sodic > saline soils. Sodic soils showed a maximum 15-35 fold increase in the EE-GRSP and DE GRSP because of AMF inoculation (P <= 0.05). Dehydrogenase and alkaline phosphatase enzymes were greater in AMF inoculated (P < 0.05). The soil electrical conductivity, glomalin, and arbuscular abundance alone explained about 76 % variability in the plant response to AMF inoculation in these soils. This study concludes that the use of native AMF with the important cropping system can be an agronomically sound option to cope with abiotic stress in salt-affected soils.

Automated summary

This study aimed to investigate the use of plant-microbe interactions with arbuscular mycorrhizal fungi (AMF) to enhance crop productivity and tolerance to salt-affected soils. The results showed that the spore density of AMF was higher in sodic soil under the rice-wheat cropping system compared to sorghum-based systems. Additionally, the colonization and abundance of AMF were greater in sodic and normal soils, respectively. The study also found that AMF inoculation increased plant height, biomass, P content, P uptake, K+/Na+, EE-GRSP, DE GRSP, dehydrogenase, and alkaline phosphatase activity in the soil.