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. 2022 May 22;10(5):1066.
doi: 10.3390/microorganisms10051066.

Effects of Humic Substances on the Growth of Pseudomonas plecoglossicida 2,4-D and Wheat Plants Inoculated with This Strain

Arina Feoktistova  1 , Margarita Bakaeva  1 , Maxim Timergalin  1 , Darya Chetverikova  1 , Aliya Kendjieva  1 , Timur Rameev  1 , Gaisar Hkudaygulov  1 , Aleksey Nazarov  2 , Guzel Kudoyarova  1 , Sergey Chetverikov  1
Affiliations

Effects of Humic Substances on the Growth of Pseudomonas plecoglossicida 2,4-D and Wheat Plants Inoculated with This Strain

Arina Feoktistova et al. Microorganisms. .

Abstract

Both rhizosphere bacteria and humic substances (HSs) can promote plant growth when applied individually and even greater effects of their combination have been demonstrated. We aimed to elucidate the relative importance of the stimulating effects of HSs on bacterial growth and the effects of the combination of bacteria and HSs on plants themselves. The effects of humic (HA) and fulvic acids (FA) (components of humic substances) on the growth of Pseudomonas plecoglossicida 2,4-D in vitro were studied. We also studied the effects of this bacterial strain and HSs applied individually or in combination on the growth of wheat plants. Although the 2,4-D strain showed low ability to use HSs as the sole source of nutrition, the bacterial growth rate was increased by FA and HA, when other nutrients were available. HSs increased root colonization with bacteria, the effect being greater in the case of HA. The effects on roots and shoots increased when bacteria were associated with HSs. FA+ 2,4-D was more effective in stimulating shoot growth, while HA + 2,4-D was in the case of root growth. The latter effect is likely to be beneficial under edaphic stresses.

Keywords: Pseudomonas plecoglossicida 2,4-D; humic and fulvic acids; humic substances; rhizosphere bacteria; wheat plants.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Total length of all seminal roots (a), number of lateral roots (b), and root mass (c) of wheat plants 7 days after treatment with Pseudomonas plecoglossicida 2,4-D (bac), humic (HA), and fulvic (FA) acids, and their combinations (bac + HA and bac + FA). Means statistically significant difference from each other are indicated by different letters, p ≤ 0.05, n = 15 (ANOVA followed by Duncan’s test).
Figure 2
Figure 2
Images of wheat plants 7 days after treatment with Pseudomonas plecoglossicida 2,4-D (bac), humic (HA), and fulvic (FA) acids, and their combinations (bac + HA and bac + FA).
Figure 3
Figure 3
Total length of all leaves (a) and shoot mass (b) of wheat plants 7 days after treatment with Pseudomonas plecoglossicida 2,4-D (bac), humic (HA), and fulvic (FA) acids, and their combinations (bac + HA and bac + FA). Means statistically significant difference from each other are indicated by different letters, p ≤ 0.05, n = 15 (ANOVA followed by Duncan’s test).
Figure 4
Figure 4
Auxin content in wheat seedling 3 days after treatment with Pseudomonas plecoglossicida 2,4-D (bac), humic (HA), and fulvic (FA) acids, and their combinations (bac + HA and bac + FA). Means statistically significant difference from each other are indicated by different letters, p ≤ 0.05, n = 9 (ANOVA followed by Duncan’s test).
See this image and copyright information in PMC

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