Isolation and evaluation of summer legumes Rhizobia as PGPR

Abstract

Rhizobia are bacteria well known for biological nitrogen fixation through symbioses. These bacteria may also perform as plant growth promoting rhizobacteria (PGPR). In this study the role of rhizobia as PGPR was studied. Rhizobia was isolated from the root nodules of various summer legumes including Glycine max (Soybaen), Vigna radiata (Mung bean), Vigna unguiculata (Cowpea), Susbenia grandiflora (Sesbania) and Cymposistetra gonoloba (Guar) grown at New Developmental Farm (NDF), the University of Agriculture Peshawar, Pakistan during summer 2011. Rhizobia were isolated from root nodules by using yeast minitol agar media, pure culture of each isolate was prepared and examined for various PGPR traits. Data revealed that 9, 83, 47 and 21% of tested strains were found to produce cyanide (HCN), siderophores, indole-acetic acid (IAA) and solubilized phosphorus respectively. Among the tested rhizoial isolates, rhizobia isolated from Vigna radiata showed highest PGPR activity fallowed by Glycine max while relatively lower PGPR activity was observed for rhizobial isolates of Cymposistetra gonoloba (Guar). All the tested isolates were gram negative. Soybaen and cowpea isolates were found to be fast growing while mung bean, susbenia and guar were slow growing in nature. This study indicates that rhizobial isolates of Vigna radiata and Glycine max have the capability to be used as PGPR.

Comparative potential of Rhizobium species for the growth promotion of sunflower (Helianthus annuus L.)

“…The tested isolates produced auxin as IAA equivalents with variable amount on respective media. Our results corroborated the results of Adnan et al (2016) who isolated rhizobia from nodules of five different summer legumes and found that 47% of isolated rhizobial species were capable of producing IAA.…”

“…Different Rhizobium sp isolated from different legumes are reported to make an association with nonlegumes and act as PGPR (Hussainet al, 2009;Mia and Shamsuddin, 2010;Qureshi et al, 2013;Naveed et al, 2015a;Adnan et al, 2016). Rhizobium species as PGPR possess various mechanisms which are responsible for stimulating plant growth such as production of phytohoromone, siderophores, cyanide, killing harmful pathogens by lytic enzymes, antibiotics, enhancing micro and macro-nutrients mobilization like phosphate solubalization, quorum-sensing signal interference, organic compounds, inducing systemic resistance, nitrogen fixation, biofilm formation, releasing ACC deaminase and symbiotic relation between plant and microbes (Alamiet al, 2000;Compant et al 2005;Bhattacharyya and Jha, 2012;Adnan et al, 2016;Jimenez-Gomez et al, 2016).…”

Relative potential of rhizobium species to enhance the growth and yield attributes of cotton (Gossypium hirsutum L.)

“…Rhizobial inoculum left potential impact on cotton plants and increased the biomass and yield parameters of cotton crop including number of bolls per plant, boll weight and seed cotton yield. It might be attributed to different rhizospheric-synergistic effects of rhizobia such as biocontrol against pathogens (Hossain and Mårtensson, 2008), cyanide production (Adnan et al, 2016), production of exopolysacharides, antioxidants, better colonization ability (Hussain et al, 2014), growth hormones (Qureshi et al, 2013) like IAA in the cotton rhizosphere which improved root morphology, root proliferation (Hussain et al, 2009) thus better root system for acquisition and uptake of mineral nutrients (N, P and K) as seen in case of rice seed and seedling inoculation with different Rhizobium spp (i.e. Bradyrhizobium sp IRBG271, R. leguminosarum bv.…”

“…Seed inoculation of cotton with rhizobial isolates put positive influence on physiology of cotton plants, thus, enhancing the photosynthetic activity and transpiration rate. This improvement by rhizobia may be due to the production of siderophoresenhancing iron (part of chlorophyll) supply, growth hormones (Adnan et al, 2016) and exopolysaccharide which facilitate water and mineral supply throughimproved root system (Egamberdieva and Kucharova, 2009;Hussain et al, 2014) ensuring better plant physiology for normal growth and development of cotton plants. These finding of our experiment according to an experiment in which inoculation of maize seeds with two PGPR strains (B.phytofirmans PsJN and Enterobactersp.…”