Biochar-Based Inoculum of Bradyrhizobium Improve Plant Growth and Yield of Lupin (Lupinus angustifolius L.) under Drought Stress
Dilfuza Egamberdieva, Moritz Reckling, Stephan Wirth
Leibniz-Centre for Agricultural Landscape Research (ZALF), Germany
The legume-Rhizobium symbiosis is known as the most efficient system for biological nitrogen fixation (BNF) through nodulation in legume roots. Drought stress is a major abiotic impact on the symbiotic performance of legumes, inhibiting plant growth, and decreasing yields. Biochar is a fine-grained substrate rich in organic carbon that is produced by pyrolysis or by heating biomass in a low oxygen environment and has been used worldwide as a soil amendment to increase soil fertility and plant growth. It is also considered as a suitable carrier material for bacterial inoculants. We have evaluated the potential of a biochar for suitability as a carrier for Bradyrhizobium sp. (Lupinus) under irrigation and drought conditions. The three types of char were used as carrier material for bacteria: (i) hydrochar (HTC) from maize silage (ii) pyrolysis biochar from maize (MBC), and (iii) pyrolysis biochar from wood (WBC). A field experiment was conducted at the experimental field station of Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany. In the pot experiment survival of Bradyrhizobium sp. (BR) populations were higher in HTC-char carrier material as compared to pyrolysis biochar from maize (MBC), and pyrolysis biochar from wood (WBC). The HTC based Bradyrhizobium sp. inoculant (HTC-BR) significantly enhanced plant growth, uptake of N and P, and nodulation of lupin under drought compared to inoculation with BR strain. The survival of BR was more competent at drought stress condition, when introduced as HTC-based inocula compared to a direct inoculation. The result of field experiment showed, that the HTC-BR inoculant was effective in lupin growth promotion, and pod formation of lupin under both irrigated and drought conditions in comparison to the un-inoculated control. From our study, we conclude in general that HTC as carrier substrate increased survival of Bradyrhizobium sp. inoculum, improving plant growth, nutrient uptake and symbiotic performance of lupin under drought stress. Our results imply that biochar based microbial inoculants are a promising practical approach to improve growth of legumes under hostile conditions.
Keywords: Extreme conditions, grain legumes, hydrochar, inoculation, water scarcity
Contact Address: Dilfuza Egamberdieva, Leibniz-Centre for Agricultural Landscape Research (ZALF), Inst. for Landscape Biogeochemistry, Eberswalder Str. 84, 15374 Müncheberg, Germany, e-mail: Dilfuza.egamberdievazalf.de