Effects of Biofertilizer Produced from Bradyrhizobium and Streptomyces griseoflavus on Plant Growth, Nodulation, Nitrogen Fixation, Nutrient Uptake, and Seed Yield of Mung Bean, Cowpea, and Soybean

Aung Zaw Htwe,Takeo Yamakawa,Kyi Moe,Seinn Moh Moh,Khin Myat Soe

doi:10.3390/agronomy9020077

Abstract

The use of biofertilizers is important for sustainable agriculture, and the use of nodule bacteria and endophytic actinomycetes is an attractive way to enhance plant growth and yield. This study tested the effects of a biofertilizer produced from Bradyrhizobium strains and Streptomyces griseoflavus on leguminous, cereal, and vegetable crops. Nitrogen fixation was measured using the acetylene reduction assay. Under N-limited or N-supplemented conditions, the biofertilizer significantly promoted the shoot and root growth of mung bean, cowpea, and soybean compared with the control. Therefore, the biofertilizer used in this study was effective in mung bean, cowpea, and soybean regardless of N application. In this study, significant increments in plant growth, nodulation, nitrogen fixation, nitrogen, phosphorus, and potassium (NPK) uptake, and seed yield were found in mung beans and soybeans. Therefore, Bradyrhizobium japonicum SAY3-7 plus Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus are effective bacteria that can be used together as biofertilizer for the production of economically important leguminous crops, especially soybean and mung bean. The biofertilizer produced from Bradyrhizobium and S. griseoflavus P4 will be useful for both soybean and mung bean production.

Highlights

Leguminous crops are important cash crops, and demand for them for domestic consumption and export is increasing in Myanmar
The plants to which biofertilizer was applied showed increased shoot growth in komatsuna, and root growth in wheat, maize, sweet pea, and common bean. These results demonstrate that the biofertilizer used in our study was effective in mung bean, cowpea, and soybean regardless of N application
We observed significant increases in plant growth, nodulation, and nitrogen fixation in mung bean and soybean

Summary

Introduction

Leguminous crops are important cash crops, and demand for them for domestic consumption and export is increasing in Myanmar. About one-third of human dietary protein is derived from grain legumes [2]. In addition to their being a rich source of protein, legumes are important because they have the unique ability to produce substantial amounts of organic nitrogen through symbiotic biological nitrogen fixation [3]. Legume–rhizobia symbiosis can provide an easy, inexpensive way to maintain soil fertility and improve crop production [4]. Leguminous plants can establish symbiosis with bacteria belonging to the genera Rhizobium, Bradyrhizobium, Sinorhizobium, Azorhizobium, Mesorhizobium, and Allorhizobium, collectively known as Agronomy 2019, 9, 77; doi:10.3390/agronomy9020077 www.mdpi.com/journal/agronomy

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Discussion

Conclusion