Nitrogen‐fixing bacteria with multiple plant growth‐promoting activities enhance growth of tomato and red pepper

Abstract

As a suitable alternative to chemical fertilizers, the application of plant growth-promoting rhizobacteria has been increasing in recent years due to their potential to be used as biofertilizers. In the present work, 13 nitrogen-fixing bacterial strains belonging to 11 different genera were tested for their PGP attributes. All of the strains were positive for 1-aminocyclopropane-1-carboxylate deaminase (ACCD), indole-3-acetic acid (IAA), salicylic acid, and ammonia production while negative for cellulase, pectinase, and hydrocyanic acid production. The strains Pseudomonas sp. RFNB3 and Serratia sp. RFNB14 were the most effective in solubilizing both tri-calcium phosphate and zinc oxide. In addition, all strains except Pseudomonas sp. RFNB3 were able to oxidize sulfur, and six strains were positive for siderophore synthesis. Each strain tested in this study possesses at least four PGP properties in addition to nitrogen fixation. Nine strains were selected based on their multiple PGP potential, particularly ACCD and IAA production, and evaluated for their effects on early growth of tomato and red pepper under gnotobiotic conditions. Bacterial inoculation considerably influenced root and shoot length, seedling vigor, and dry biomass of the two crop plants. Three strains that demonstrated substantial effects on plant performance were further selected for greenhouse trials with red pepper, and among them Pseudomonas sp. RFNB3 resulted in significantly higher plant height (26%) and dry biomass (28%) compared to control. The highest rate of nitrogen fixation, as determined by acetylene reduction assay, occurred in Novosphingobium sp. RFNB21 inoculated red pepper root (49.6 nM of ethylene/h/g of dry root) and rhizosphere soil (41.3 nM of ethylene/h/g of dry soil). Inoculation with nitrogen-fixing bacteria significantly increased chlorophyll content, and the uptake of different macro- and micro-nutrient contents enhancing also in red pepper shoots, in comparison with uninoculated controls. The population estimation studies showed that nitrogen-fixing as well as total heterotrophic bacteria were also noticeably increased in soil and plant samples. The findings of this study suggest that certain nitrogen-fixing strains possessing multiple PGP traits could be applied in the development of biofertilizers.

Rhizospheric changes of fungal and bacterial communities in relation to soil health of multi-generation apple orchards

“…in crop defense and plant competitiveness is well known. Their functionality varies from antibiotic activity in bio-control, up to plant growth promotion mediated by hormone-like compounds, and to other functionalities suitable to increase nutrient availability such as solubilization of phosphate, sulfur and zinc, siderophore synthesis and nitrogen fixation (Hahm et al, 2012;Islam et al, 2013;Raaijmakers et al, 2002;Weller, 2007;Hol et al, 2013). High matches of a group of Pseudomonas spp.…”

Assessment of plant growth promoting activities and abiotic stress tolerance of Azotobacter chroococcum strains for a potential use in sustainable agriculture

“…They can operate directly through the production of substances which promote growth and increase nutrient availability in soil and their uptake, or indirectly through the suppression of plant pathogens (Ribeiro and Cardoso, 2012). Nitrogen-fixing bacterial strains, including several belonging to the genus Azotobacter, have been used successfully in agriculture applications (Islam et al, 2013). These strains have been characterized well for their excellent nitrogen fixing properties as well as for their siderophores, indol-3-acetic acid and exopolysaccharides (EPS) production, which may benefit plant growth/nutrient availability and soil water retention properties (Gauri et al, 2012).…”

Kemampuan Mikrob Endofit dan Rizosfer Tanaman Karet dalam Mengendalikan Rigidoporus lignosus

“…Bakteri antagonis diidentifikasi menggunakan teknik polymerase chain reaction (PCR) dengan primer universal, yaitu forward primer 27F (5'-AGAGTTTGATCCTGGCTCAG-3') dan reverse primer 1429R (5'-GGTTACC TTGTTACGACTT-3') (Islam et al 2012 …”

“…Singh et al (2010) menyatakan bahwa aplikasi bakteri pelarut fosfat memiliki korelasi positif terhadap performa tanaman dengan meningkatkan pertumbuhan dan meningkatkan hasil panen tanaman kedelai sebesar 23.88%. Inokulasi bakteri fiksasi nitrogen pada tanaman tomat dan cabai merah diketahui mampu meningkatkan klorofil tanaman, hara makro dan mikro tanaman, vigor, dan biomassa tanaman (Islam et al 2012).…”