Date Published: July 01, 2018
Author(s): Amaral Machaculeha Chibeba, Stephen Kyei-Boahen, Maria de Fátima Guimarães, Marco Antonio Nogueira, Mariangela Hungria.
•Soybean N demand can be fulfilled by biological nitrogen fixation (BNF).•Bradyrhizobium strains from Brazil and USA were tested in Brazil and Mozambique.•Inoculation resulted in grain yield gains of 4–5% in Brazil and 20–29% in Mozambique.•Transference of BNF technologies is feasible, speeding up the production system.•Exotic soybean Bradyrhizobium strains can highly benefit soybean in Mozambique.
Soybean [Glycine max (L.) Merrill] has potential to play a major role in responding to global food insecurity that results from mounting demographic pressures. The world population is projected to grow beyond 10 billion by 2100 (Gerland et al., 2014), and much of the increase will occur in Africa (Cleland, 2013), where hunger is already a threat. With high concentration of seed protein (40%), that provides all essential amino acids in sufficient amounts for human health, and high seed oil content (20%), soybean has many uses, encompassing human food, animal feed and biofuels. Moreover, soybean offers a number of advantages in sustainable cropping systems, including the ability to symbiotically fix atmospheric nitrogen (N2), which obviates the reliance on N-fertilizers.
Brazilian soils are originally devoid of rhizobia capable of nodulating soybean, but strain selection programs started early with soybean expansion in the 1960s (Hungria et al., 2006a, Hungria and Mendes, 2015). Elite inoculant strains from Australia and the USA were field tested in Brazil to verify their adaptability to the local agro-climatic conditions, N2-fixation effectiveness and ability to compete for nodule occupancy (Hungria and Mendes, 2015). Following years of extensive trials and research improvements, four strains, B. elkanii SEMIA 587 and SEMIA 5019, B. japonicum SEMIA 5079 and B. diazoefficiens SEMIA 5080 are currently employed in commercial inoculants for the crop in Brazil, in single or double-strain combinations (Hungria et al., 2005, Hungria et al., 2013, Campo et al., 2009). The double-strain inoculant SEMIA 5079 + 5080 represents over 80% of the commercial inoculants sold in the country and is the farmers’ choice in the Cerrados region (Hungria et al., 2006a, Hungria and Mendes, 2015), an edaphic type of savannah. Yield enhancements of 4–12% attributable to the inoculant combination SEMIA 5079 + 5080 have been reported in bradyrhizobia populated soils (Vargas and Hungria, 2000, Campo et al., 2009).