Evaluation of fluorescent Pseudomonas spp. with single and multiple PGPR traits for plant growth promotion of sorghum in combination with AM fungi

Abstract

Traits involved in plant growth promotion by bacteria are ambiguously decided as phytohormones, siderophores, HCN, proteases, chitinases, cellulases, ammonia, exopolysaccharide production and phosphate solubilization or antagonistic activity. A total of 40 fluorescent Pseudomonas strains were isolated from diverse soils of various agro-ecosystems of India. Among these 7 strains viz, P1, P10, P13, P18, P21, P28 and P38 were selected depending on their character of possessing single or multiple PGPR traits. These isolates individually and in combination with AM fungi (Glomus fasciculatum and Glomus aggregatum) were used for treating sorghum seeds. 25 days after sowing, plants were analysed for different plant growth promoting parameters. It was observed that strains in presence of mycorrhizae performed well compared to the strains devoid of mycorrhizae. Pseudomonas sp. P1 possessing GA3, EPS production and 'P' solubilization performed well. Pseudomonas sp. P38 which was a volatile (HCN) producer but a good phosphate solubilizer did not perform well. Strain P28 with multiple PGPR traits did not show the expected out come. Results varied when mycorrhizae was used in combination. P10 and P13 which were good in IAA, GA3, EPS, siderophore and 'P' solubilization performed well with mycorrhizae, with an overall increase in plant biomass, leaf area, total chlorophyll and mycorrhizal infection compared to other combinations. Here, strain P1 in combination with mycorrhizae did not show significant increase in plant growth compared to P10 and P13. Hence, mere possession of multiple PGPR traits does not confer fluorescent Pseudomonas strains as PGPR. Further studies have to be carried out in order to evaluate the other traits which may be involved in plant growth promotion.

Forage sorghum quantity and quality as affected by biological phosphorous fertilization

“…The results indicated that the combined use of AM fungi and PB was a more effective treatment than the single use of either PB or AM fungus in affecting sorghum yield and quality. These results are similar to the results of Kumar et al (2012) who found that fluorescent Pseudomonas strains increased sorghum growth more efficiently in the presence of mycorrhizal fungi than in the absence of the fungi. Similar to our used bacterial features (Table 2), PGPR colonize plant roots and exert beneficial effects on plant growth and development by a wide variety of mechanisms.…”

“…Mycorrhization of wheat (Triticum aestivum L.) and maize (Zea mays L.) was not affected by different Azospirillum species or by a genetically modified derivative of Azospirillum brasilense overproducing indole-3-acetic acid, indicating the variations in AM fungi-PGPR interactions (Russo et al, 2005). Similar results were found by Kumar et al (2012). Crop quality including the rates of fibre, starch and proteins is an important aspect affecting the use and the efficiency of crop plants by the consumers.…”

“…The positive interactions between AM fungi and PGPR can increase root colonization and improve the growth of the host plant (Sabannavar & Lakshman, 2011). For example, Kumar et al (2012) investigated the single and the combined effects of PGPR strains with mycorrhizal fungi on the growth of sorghum under greenhouse conditions. They found that the PGPR strains with plant promoting activities including phosphate solubilization acted more efficiently in the presence of mycorrhizal fungi.…”

MULTI-TRAITS OF NON-PATHOGENIC FLUORESCENT <i>PSEUDOMONAS</i> AND EVALUATION OF THEIR POTENTIEL AS BIOCONTROL AGENTS

“…IAA, a member of phytohormone group, acts as important signal molecule in the regulation of plant growth (Kumar et al, 2012). In our study most of the Pseudomonas isolates were positive for IAA production (76%).…”

Effects of rhizobacteria on the respiration and growth of Cerasus sachalinensis Kom. seedlings

“…Bacillus and Pseudomonas were the main PGPR used in agricultural practice (Pandey et al, 2005;Niu et al, 2011). Pseudomonas could promote plant growth by facilitating phosphate solubilization or antagonistic activity or by producing phytohormones, siderophores and hydrogen cyanide (Kumar et al, 2012). Pseudomonas also could increase biomass (Gholami et al, 2009), enhance yield (Rosas et al, 2009) and relieve the damage of water stress (Sandhya et al, 2010) and drought stress (Kohler et al, 2009) to the plants.…”