Development of liquid rhizobial inoculants and pre-inoculation of alfalfa seeds

Abstract

Application of liquid microbial inoculants on legume seeds is a sustainable agricultural practice that can improve plant nutrient uptake and increase crop productivity. Inoculants should provide long-term survival of rhizobia in the final product and after application, to legume seeds. Ten different medium formulations of microbial inoculants were examined (yeast mannitol broth with the addition of agar, sodium-alginate, calcium chloride, glycerol or ferric chloride and combinations thereof) for the survival of the efficient nitrogen-fixing rhizobium, Sinorhizobium (Ensifer) meliloti L3Si strain. The most suitable liquid inoculant for survival of L3Si during a storage time of 150 days was the medium formulation containing glycerol in combination with agar or sodium-alginate. Alfalfa seeds were pre-inoculated with four formulations (yeast mannitol broth (YMB), YMB with agar (1 g L-1), YMB with 1 or 5 g L-1 sodium-alginate) for up to three months. Seeds pre-inoculated and stored for one month produced successful alfalfa plants. The nitrogen content in alfalfa obtained from pre-inoculated seeds one month before sowing was adequate and ranged from 3.72-4.19%. Using S. meliloti-based liquid inoculants for alfalfa and application of the pre-inoculation technique can increase the quality of alfalfa crops and reduce cultivation cost.

Microbial inoculants: reviewing the past, discussing the present and previewing an outstanding future for the use of beneficial bacteria in agriculture

“…Alfalfa ( Medicago sativa L.) is present in pastures in temperate and subtropical, and arid and semi-arid areas. Buntić et al (2019) developed a liquid-formulated inoculant containing Sinorhizobium (= Ensifer ) meliloti strain L3Si allowing better shelf life, pre-inoculation and performance in alfalfa, as there were no liquid inoculants available with this strain. Shoot N content of plants originated from seeds pre-inoculated 1 month before sowing ranged from 3.72 to 4.19%, whereas the control with N-fertilizer had 4.03%; the highest SDW value was of 27.12 mg/plant in the inoculated plants, higher than the control with N-fertilizer (20.20 mg/plant), indicating a high effectiveness of the liquid formulation (Buntić et al 2019).…”

Roles of culture media and oxygen transfer in the scale-up from shake flasks to pneumatic bioreactor of the plant growth-promoting bacterium Rhizobium phaseoli

“…The accepted criterion is that the cell viability of the product must be in the order of 10 7 -10 9 CFU mL −1 to be recognized as a commercial product (Brahmaprakash and Sahu, 2012;Deaker et al, 2016;de Souza and Ferreira, 2017). Likewise, there are a few studies on the production of liquid rhizobacterial inoculants (Okon and Itzigsohn, 1995;Trujillo-Roldán et al, 2013;Buntić et al, 2019) and scaling-up and application on an industrial scale (Okon and Itzigsohn, 1995;Trujillo-Roldán et al, 2013;Jagjot et al, 2018;Lobo et al, 2019) due to the industrial secrecy of most companies. Moreover, few studies are based on the definition of the critical process parameters in the production of cell biomass of rhizobacterial inoculants (e.g., oxygen, pH, and temperature).…”

The effect of bacterial isolates from rhizosphere soils on wheat and barley seed germination

“…Soil microorganisms are important for agriculture as they promote the circulation of plant nutrients on the one side and reduce the need for chemical fertilizers on the other side Effect of rhizosphere bacteria on seed germination, Buntic et al ZEMLJISTE I BILJKA,VOL 68,No 2,[1][2][3][4][5][6][7][8][9][10][11] Original paper doi: 10.5937/ZemBilj1902001B 2 (Ҫakmakҫi et al 2007;Yadav et al, 2010). A large number of bacteria including species of Pseudomonas, Azospirillum, Azotobacter, Klebsiella, Enterobacter, Alcaligenes, Arthrobacter, Burkholderia, Bacillus, Rhizobium (Bradyrhizobium, Sinorhizobium) and Serratia have been reported as PGPR to improve plant growth (Yadav et al, 2010;Buntić et al, 2019, Stajkovic et al, 2011, Kumawat et al, 2019. They can improve the quality of plant growth directly and/or indirectly.…”