Molybdate in Rhizobial Seed-Coat Formulations Improves the Production and Nodulation of Alfalfa

Abstract

Rhizobia-legume symbiosis is the most well researched biological nitrogen fixation system. Coating legume seeds with rhizobia is now a recognized practical measure for improving the production of legume corp. However, the efficacy of some commercial rhizobia inoculants cannot be guaranteed in China due to the low rate of live rhizobia in these products. A greenhouse experiment was conducted to assess the effects of different rhizobial inoculant formulations on alfalfa productivity and nitrogen fixation. Two rhizobia strains, (ACCC17631 and ACCC17676), that are effective partners with alfalfa variety Zhongmu No. 1 were assessed with different concentrations of ammonium molybdate in seed-coat formulations with two different coating adhesives. Our study showed that the growth, nodulation, and nitrogen fixation ability of the plants inoculated with the ACCC17631 rhizobial strain were greatest when the ammonium molybdate application was0.2% of the formulation. An ammonium molybdate concentration of 0.1% was most beneficial to the growth of the plants inoculated with the ACCC17676 rhizobial strain. The sodium carboxymethyl cellulose and sodium alginate, used as coating adhesives, did not have a significant effect on alfalfa biomass and nitrogen fixation. However, the addition of skimmed milk to the adhesive improved nitrogenase activity. These results demonstrate that a new rhizobial seed-coat formulation benefitted alfalfa nodulation and yield.

Seed Coating: A Tool for Delivering Beneficial Microbes to Agricultural Crops

“…Recently, biochar and chitosan have been also considered as fillers/carriers for microbial seed coating (Głodowska et al, 2016; Głodowska et al, 2017; Ruiz-de-la-Cruz et al, 2017). Binders, natural or synthetic polymers such as methyl cellulose (Hartley et al, 2004; Haikal, 2008; Swaminathan et al, 2016; Amutha, 2017; Lopisso et al, 2017), carboxymethyl cellulose (Sharma et al, 2003; Roesti et al, 2006; Nawar, 2007; Zhou et al, 2017), gum arabic (Kyei-Boahen et al, 2001; Ehteshamul-Haque et al, 2007; Dawar et al, 2008; Singh et al, 2014), or polysaccharide Pelgel (Jensen et al, 2000; Li et al, 2002; Ugoji et al, 2006) are generally added during or toward the end of the coating process in order to bind the exogenous materials and reduce the amount of dust in the final product (Pedrini et al, 2017). Some adhesives (e.g., gum arabic and xanthan gum) can also be used to extend the survival of PBM applied to seeds (Jambhulkar et al, 2016).…”

“…oryzae in rice (Palupi et al, 2017) and enhanced canola height and biomass under greenhouse and field conditions (Lally et al, 2017). As the most frequently used rhizobial genus, Rhizobium has also been successfully coated singly and in consortia with other PBM, which resulted in positive effects on plant growth and yield (Fatima et al, 2006; Dawar et al, 2008; Dal Cortivo et al, 2017; Zhou et al, 2017; Padhi and Pattanayak, 2018). In some cases, the application of a certain ingredient for seed coating can limit the positive role of Rhizobium in plants.…”

Development of formulations for the application of biofertilizers based on autochthonous microorganisms for high addedvalue crops = Desarrollo de formulaciones para la aplicación de biofertilizantes basados en microorganismos autóctonos para productos agroalimentarios con alto valor añadido

“…These autochthonous symbionts show superior characteristics of competitiveness in nodule infection and occupancy due to their better adaptation to the local agro-climatic conditions (Meghvansi et al, 2010) and to their positive interaction with the resident microbial populations . Thus, rhizobial strains isolated under local field conditions usually result in successful inoculants, as already reported for various crops , including P. vulgaris (Mulas et al, , 2015Yanni et al, 2016;Zhou et al, 2017).…”

Formulation of a Highly Effective Inoculant for Common Bean Based on an Autochthonous Elite Strain of Rhizobium leguminosarum bv. phaseoli, and Genomic-Based Insights Into Its Agronomic Performance

“…These autochthonous symbionts show superior characteristics of competitiveness in nodule infection and occupancy due to their better adaptation to the local agro-climatic conditions (Meghvansi et al, 2010) and to their positive interaction with the resident microbial populations (Tena et al, 2016). Thus, rhizobial strains isolated under local field conditions usually result in successful inoculants, as already reported for various crops (Dall'Agnol et al, 2013), including P. vulgaris (Mulas et al, 2011(Mulas et al, , 2015Yanni et al, 2016;Zhou et al, 2017).…”