Field Crops Research 136 (2012) 97–106 Contents lists available at SciVerse ScienceDirect Field Crops Research jou rn al h om epage: www.elsevier.com/locate/fcr Seeds enriched with phosphorus and molybdenum as a strategy for improving grain yield of common bean crop Rafael Sanches Pacheco a , Luciana Fernandes Brito a , Rosangela Straliotto b , Daniel Vidal Pérez c , Adelson Paulo Araújo a,∗ a Universidade Federal Rural do Rio de Janeiro, Departamento de Solos, BR 465 km 7, CEP 23890-000, Seropédica – RJ, Brazil b Embrapa Agrobiologia, BR 465 km 7, CEP 23890-000, Seropédica – RJ, Brazil c Embrapa Solos, Rua Jardim Botânico 1024, CEP 22460-000, Rio de Janeiro – RJ, Brazil a r t i c l e i n f o Article history: Received 8 March 2012 Received in revised form 24 July 2012 Accepted 26 July 2012 Keywords: Rhizobium Phaseolus vulgaris N2 fixation Nodulation Seed a b s t r a c t Sowing seeds with high concentrations of P or Mo can improve growth and nodulation of common bean (Phaseolus vulgaris) plants. However, the performance of the bean crop originating from seeds enriched with P and Mo has not yet been assessed under field conditions. This study aimed to evaluate the effect of sowing seeds enriched with P and Mo, harvested from plants that received foliar sprayings of P or Mo or both, on growth and yield of common bean crop. Seeds with contrasting concentrations of P and Mo were sown in three field experiments in Brazil (in 2006 and 2008 in Rio de Janeiro State, and in 2009 in Goiás State) with different N sources (control without N, seed with rhizobia inoculation, rhizobia inoculation plus 40 kg N ha -1 side-dressed, mineral N with 60 kg N ha -1 ). In 2006, seeds enriched with P and Mo increased nodule mass at 32 days after emergence (DAE), shoot N and biomass at 48 DAE, and grain yield and N content, for most combinations of the three cultivars and N sources evaluated. In 2008, the highest shoot growth at 57 DAE and grain yield were obtained with low-P high-Mo seeds, which was partially due to the higher Mo concentration of these seeds. In 2009, seeds enriched with P and Mo increased nodule mass at 34 DAE and grain yield but only for plants receiving inoculation plus side-dressed N. The results demonstrate the benefits of seeds with high concentrations of P and Mo for improving bean yield, although such yield increases were more effective for plants inoculated with rhizobia than amended with N. Sowing enriched seeds, associated with rhizobia inoculation and side-dressed N, provided grain yields much higher than the average common bean yields in Brazil. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Common bean (Phaseolus vulgaris) is the most important food legume worldwide, providing the chief source of dietary protein for more than 300 million people (CIAT, 2001). In spite of some gains in yield over the last decades, bean productivity is still very low in many regions of Latin America. In Brazil, common bean has historically been cultivated on small subsistence farms, but pro- found changes have occurred during last years. Cultivated areas lower than 10 ha, between 10 and 50 ha or higher than 50 ha have produced, respectively, 26.3, 22.5 and 51.2% of the Brazilian bean yield in 2006, with respective average productivity of 635, 1.089 and 1.064 kg ha -1 , showing the increasing participation of large producing areas (IBGE, 2009). However, areas planted to bean of less than 10 ha were present in more than 700.000 rural properties (IBGE, 2009), stressing the social relevance of the crop in Brazil. ∗ Corresponding author. Tel.: +55 21 3787 3772; fax: +55 21 3787 3772. E-mail address: aparaujo@ufrrj.br (A.P. Araújo). The extremely diverse cultivation methods and levels of technol- ogy and inputs employed in the common bean crop require distinct research approaches for improving bean yield and sustainability. Although common bean can acquire considerable amounts of N through the biological fixation in the field (Rennie and Kemp, 1984; Duque et al., 1985; Hardarson et al., 1993), commercial bean crops are often fertilized with N owing to poor nodulation and lack of responses to inoculation under field conditions (Graham et al., 2003). Such N amendments can in turn inhibit nodulation and N 2 fixation due to the high ability of common bean to uptake N from the soil and the high sensitivity of bean symbiosis to soil nitrate (George and Singleton, 1992; Leidi and Rodríguez-Navarro, 2000; Kimura et al., 2004). However, some evidence indicates that low levels of N fertilizer applied to the bean crop, particularly when associated with the inoculation with selected rhizobial strains, can stimulate plant growth, N 2 fixation and grain yield (Rennie and Kemp, 1984; Henson and Bliss, 1991; Hungria et al., 2003). More- over, the response to rhizobia inoculation is associated with the cropping history of the land area, since previous bean crops can reduce the efficiency of inoculation (Vargas et al., 2000). 0378-4290/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fcr.2012.07.017