Vol.:(0123456789) 1 3 Journal of Plant Growth Regulation https://doi.org/10.1007/s00344-019-09939-4 Performance of Bradyrhizobium and Bradyrhizobium–Azospirillum in Alleviating the Efects of Water-Restrictive Conditions During the Early Stages of Arachis hypogaea Growth Adriana B. Cesari 1  · Natalia S. Paulucci 1  · Miguel López‑Gómez 2  · Javier Hidalgo‑Castellanos 2  · Carmen Lluch Plá 2  · Marta S. Dardanelli 1 Received: 15 September 2018 / Accepted: 23 January 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The objective of the work is to evaluate whether Bradyrhizobium sp. SEMIA6144 and Azospirillum brasilense Az39 can be used for inoculation to mitigate the negative efect of water restriction on growth of Arachis hypogaea. In this study, nitrogenase activity was determined by measuring the H 2 evolution in an open-fow system, and N and C concentration in plants were determined by Elemental Analyzer. Lipid peroxidation and polyamines (PA) levels were analyzed by HPLC. The results showed that the restrictive water condition (RWC) caused an 80% inhibition of the N fxation rate. Although both single and double inoculation favored peanut growth under RWC, the inoculation with SEMIA6144 was better. Peanut plants have higher numbers of nodules in the roots when inoculated with SEMIA6144 in the absence of Az39, although it was observed that the inoculation with Az39 favored root development thus allowing the appearance of more infection sites in peanut roots. In double inoculation, the demand for N in the peanut was met with greater efectiveness. PAs found in leaves were putrescine, spermidine, and spermine. The results show that SEMIA6144 inoculation reversed the negative efects of RWC on growth and nodulation peanut parameters. Simultaneous application of SEMIA6144 and Az39 improved early nodulation, efciency in N fxation and total N, thus increasing the tolerance of A. hypogaea to RWC. Our fndings provide new insights in the context of mixed inoculation and improvement of peanut production in a limited water environment. Keywords Arachis hypogaea · Legume root nodule · PGPR double inoculation · Restrictive water condition · Stress mitigation Introduction Peanut (Arachis hypogaea L.) is one of the crops in the Arachis genus that is of major economic importance and is cultivated in approximately 23 million hectares distributed worldwide (Celikkol et al. 2010). Peanut is a legume crop native from South America. The fve main peanut producers are China, India, Nigeria, USA, and Argentina with 40%, 14%, 7%, 6%, and 3% of the world’s production, respectively (MinAgri 2018). In Argentina, 378,008 ha were planted with peanuts during 2016–2017 and concentrates 85% of its pro- duction in Córdoba province (Paulucci et al. 2015; Barberis and Bongiovanni 2015; INTA 2017). It is an important oil- seed crop and a rich source of essential phytonutrients such as niacin, folate, fber, vitamin E, and antioxidant polyphe- nols (Kris-Etherton et al. 2008). In semiarid regions of the world where 70% of peanuts are grown, drought is a signifcant limitation for the produc- tion of this legume (Celikkol et al. 2010). In Argentina, the southwest territory of Córdoba province sufered the efects of the lack of rainfall in the 2017–2018 agricultural seasons. This reduction of the rains represented important losses in the yield of the peanut crop (INTA 2018). One strategy to improve plant growth under adverse conditions is inocula- tion with plant growth-promoting rhizobacteria (PGPR) * Adriana B. Cesari acesari@exa.unrc.edu.ar * Marta S. Dardanelli mdardanelli@exa.unrc.edu.ar 1 Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Córdoba, Argentina 2 Departamento de Fisiología Vegetal, Universidad de Granada, Campus de Fuentenueva, Granada, Spain