Response of Soybean to Hydrochar-Based Rhizobium Inoculation in Loamy Sandy Soil.

Dilfuza Egamberdieva,Stephan Wirth,Hua Ma,Moritz Reckling,Sonoko Dorothea Bellingrath-Kimura,Jakhongir Alimov

doi:10.3390/microorganisms8111674

Abstract

Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both greenhouse and field conditions. There were positive and significant effects of hydrochar-based inoculation on the root and shoot growth of soybean as compared to uninoculated plants grown under irrigated and drought conditions. The drought stress significantly inhibited the symbiotic performance of rhizobia with soybean. Soybean inoculated with hydrochar-based B. japonicum produced twofold more nodules under drought stress conditions as compared to plants inoculated with a commercial preparation/inoculant carrier B. japonicum (HISTICK). The N concentration of inoculated plants with hydrochar-based B. japonicum was by 31% higher than that of un-inoculated plants grown in pots and by 22% for HISTICK. Furthermore, the soybean treated with hydrochar-based B. japonicum showed higher grain yield of 29% under irrigated conditions and 40% higher under rainfed condition compared to un-inoculated plants. In conclusion, the obtained results proved the potential of hydrochar-based B. japonicum inoculant for soybean in terms of increased symbiotic performance and agronomic traits, especially under rainfed conditions.

Highlights

Soybean is an important legume and source of food, oil, and as a forage crop, is widely grown in China and other countries of the world [1,2]
Soybean establishes a symbiotic association with Bradyrhizobium japonicum, where bacteria use nutrients and carbohydrates provided by the plant and fix atmospheric nitrogen and make it bioavailable to the plant [5]
The aim of this study was to; (i) evaluate hydrochar produced from maize silage for its suitability as a carrier of Bradyrhizobium japonicum, and (ii) test the effectiveness of hydrochar-based B. japonicum inoculants forming root nodules with soybean, and (iii) survey improved growth, nutrient uptake and yield under both greenhouse and field conditions

Summary

Introduction

Soybean is an important legume and source of food, oil, and as a forage crop, is widely grown in China and other countries of the world [1,2]. Legumes, associated with rhizobia, can fix nitrogen, increase the availability of nitrogen in several agroecosystems. Half of all N (4–5 million t) supplied in agricultural systems was fixed by legumes, and it can be increased by improving the soybean-Rhizobium symbioses [3,4]. Soybean establishes a symbiotic association with Bradyrhizobium japonicum, where bacteria use nutrients and carbohydrates provided by the plant and fix atmospheric nitrogen and make it bioavailable to the plant [5]. Soybean may fix up to 50% N via its symbiosis with Bradyrhizobum japonicum present in the soil or applied as inoculants [6,7,8]

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Methods

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Discussion

Conclusion