Plant-Growth-Promoting Fungicide-Tolerant Rhizobium Improves Growth and Symbiotic Characteristics of Lentil (Lens esculentus) in Fungicide-Applied Soil

The goal of this study was to identify lentil-specific rhizobial strains with the ability to tolerate fungicide and synthesize plant growth regulators even in soils contaminated with fungicides. A fungicide-tolerant and plant-growth-promoting rhizobial strain was used to assess its impact on lentil grown in fungicide-treated soils. The tebuconazole-tolerant Rhizobium sp. strain MRL3 produced plant-growth-promoting substances when grown in the presence and the absence of tebuconazole. Tebuconazole at the recommended and two and three times the recommended doses decreased consistently the dry biomass, symbiotic properties, nutrient uptake, and seed yields of lentil plants. In contrast, the fungicide-tolerant strain MRL3 significantly increased the measured parameters when lentil was grown in soils treated with varying concentrations of tebuconazole compared to uninoculated plants. As an example, strain MRL3 with 100 μg tebuconazole/kg soil significantly increased the root nitrogen, shoot nitrogen, root phosphorus, shoot phosphorus, and seed yield by 31, 10, 41, 21, and 117%, respectively, compared to the uninoculated plants grown in soil treated solely with 100 μg tebuconazole/kg soil. In conclusion, the Rhizobium strain MRL3 may be applied as biofertilizer to enhance the performance of lentil plants in fungicide-applied soils.