56
A. Dahiya et al.
disease severity caused by Verticillium dahliae by more than 30%. In hydroponics,
P. indica increased fresh fruit biomass of tomato, the numbers of fruits, and the dry
matter content. Uninoculated Pisum sativum plants treated with the soluble phosphate (positive control) produced the highest quantity of biomass (total weight, root
weight, and shoot weight) in comparison to uninoculated control plants grown in sand
containing insoluble phosphate (Oteino et al. 2013). Thus, inoculation with bacterial strain L132 showed the highest whole plant dry weight, enhanced plant growth,
increased root, and shoot dry weight as compared to uninoculated treatments. This
suggested that these strains solubilize the insoluble phosphate compound by release
of gluconic acid present in the sand medium resulting in plant growth promotion as
compared to E. coli JM109 strain (negative control).
Increased plant growth and phosphate uptake have been reported in many crop
species as a result of the inoculation of PSB Pseudomonas sp. particularly in rice
(Gusain et al. 2015), soybean (Fankem et al. 2015), and wheat (Babana and Antoun
2006). Demissie et al. (2013) stated that the inoculation of fababean (Vicia faba
L.) with phosphate solubilizing Pseudomonas and Rhizobium isolates resulted in
enhanced plant growth under soluble phosphate limiting conditions as compared
to uninoculated plants. Inoculation with PSB to the plants produced gluconic acid
in the rhizosphere, resulted in the release of soluble phosphate, which was subsequently assimilated by the plant. However, these endophytic bacteria are also known
to express other plant growth promotion traits such as IAA production and ACC
deaminase activity, which may also have contributed to the enhanced growth of the
inoculated plants (Otieno et al. 2015).
Inoculation of the phosphate solubilizing endophytic isolate CKAM showed a
remarkable increase in seed germination, shoot length and root length, shoot dry
weight, and root dry weight of tomato under net house condition (Mehta et al. 2014).
When the endophytic isolate CKAM was inoculated/co-inoculated with E. adhaerens
(native rhizobia) to V. radiata, it significantly increased root length, shoot length, a
number of lateral roots and plant dry weight of mungbean plants in a small field trial
(Pandya et al. 2015). Endophytic bacterial strains isolated from the medicinal plant
Lonicera japonica showed growth-promoting activities in wheat (Zhao et al. 2015).
The inoculation of phosphate solubilizing endophytic fungi C. geniculata significantly promoted the growth of pigeon pea without expressing any pathogenic
symptoms (Priyadharsini and Muthukumar 2017). Similarly, co-inoculation of endophytic diazotrophs and actinobacteria, i.e., Bacillus, Enterobacter, Microbispora, and
Streptomyces significantly increased the growth parameters of sugarcane plants as
compared to individual inoculation and uninoculated plants (Kruasuwan and Thamchaipenet 2016). Nitrogen-fixing endophytic bacteria P. stutzeri A15 from the rhizosphere of rice stimulated its growth (Pham et al. 2017). The endophytic bacterial
strains isolated from rice seeds, i.e., Micrococcus yunnanensis RWL-2, Micrococcus
luteus RWL-3, Enterobacter soli strain RWL-4, Leclercia adecarboxylata RWL5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7 produced a
significant amount of IAA and such bacterial inoculation increased shoot and root
length, fresh and dry biomass, and chlorophyll content of rice plants significantly
(Shahzad et al. 2017). Inoculation of P. stutzeri strain E25 and Stenotrophomonas
A. Dahiya et al.
disease severity caused by Verticillium dahliae by more than 30%. In hydroponics,
P. indica increased fresh fruit biomass of tomato, the numbers of fruits, and the dry
matter content. Uninoculated Pisum sativum plants treated with the soluble phosphate (positive control) produced the highest quantity of biomass (total weight, root
weight, and shoot weight) in comparison to uninoculated control plants grown in sand
containing insoluble phosphate (Oteino et al. 2013). Thus, inoculation with bacterial strain L132 showed the highest whole plant dry weight, enhanced plant growth,
increased root, and shoot dry weight as compared to uninoculated treatments. This
suggested that these strains solubilize the insoluble phosphate compound by release
of gluconic acid present in the sand medium resulting in plant growth promotion as
compared to E. coli JM109 strain (negative control).
Increased plant growth and phosphate uptake have been reported in many crop
species as a result of the inoculation of PSB Pseudomonas sp. particularly in rice
(Gusain et al. 2015), soybean (Fankem et al. 2015), and wheat (Babana and Antoun
2006). Demissie et al. (2013) stated that the inoculation of fababean (Vicia faba
L.) with phosphate solubilizing Pseudomonas and Rhizobium isolates resulted in
enhanced plant growth under soluble phosphate limiting conditions as compared
to uninoculated plants. Inoculation with PSB to the plants produced gluconic acid
in the rhizosphere, resulted in the release of soluble phosphate, which was subsequently assimilated by the plant. However, these endophytic bacteria are also known
to express other plant growth promotion traits such as IAA production and ACC
deaminase activity, which may also have contributed to the enhanced growth of the
inoculated plants (Otieno et al. 2015).
Inoculation of the phosphate solubilizing endophytic isolate CKAM showed a
remarkable increase in seed germination, shoot length and root length, shoot dry
weight, and root dry weight of tomato under net house condition (Mehta et al. 2014).
When the endophytic isolate CKAM was inoculated/co-inoculated with E. adhaerens
(native rhizobia) to V. radiata, it significantly increased root length, shoot length, a
number of lateral roots and plant dry weight of mungbean plants in a small field trial
(Pandya et al. 2015). Endophytic bacterial strains isolated from the medicinal plant
Lonicera japonica showed growth-promoting activities in wheat (Zhao et al. 2015).
The inoculation of phosphate solubilizing endophytic fungi C. geniculata significantly promoted the growth of pigeon pea without expressing any pathogenic
symptoms (Priyadharsini and Muthukumar 2017). Similarly, co-inoculation of endophytic diazotrophs and actinobacteria, i.e., Bacillus, Enterobacter, Microbispora, and
Streptomyces significantly increased the growth parameters of sugarcane plants as
compared to individual inoculation and uninoculated plants (Kruasuwan and Thamchaipenet 2016). Nitrogen-fixing endophytic bacteria P. stutzeri A15 from the rhizosphere of rice stimulated its growth (Pham et al. 2017). The endophytic bacterial
strains isolated from rice seeds, i.e., Micrococcus yunnanensis RWL-2, Micrococcus
luteus RWL-3, Enterobacter soli strain RWL-4, Leclercia adecarboxylata RWL5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7 produced a
significant amount of IAA and such bacterial inoculation increased shoot and root
length, fresh and dry biomass, and chlorophyll content of rice plants significantly
(Shahzad et al. 2017). Inoculation of P. stutzeri strain E25 and Stenotrophomonas