Mechanisms of plant growth stimulation by humic substances: The role of organo-iron complexes

2004 ◽  
Vol 50 (7) ◽  
pp. 1089-1095 ◽  
Author(s):  
Y. Chen ◽  
C.E. Clapp ◽  
H. Magen
1985 ◽  
Vol 31 (11) ◽  
pp. 1026-1030 ◽  
Author(s):  
Jacek Plazinski ◽  
Barry G. Rolfe

The effect of inoculation of white clover plants with mixed cultures of Rhizobium trifolii strain ANU870 and Azospirillum brasilense strain SP245 was examined. Ratios of Rhizobium–Azospirillum (R:A) of 1:200 to 1:2500 caused an inhibition of nodulation. However, these nonnodulated plants did not show nitrogen-deficiency symptoms when grown on nitrogenfree medium. When these plants were assayed for acetylene reduction activity a low level of ethylene production was detected. A significant increase in plant dry weights was also observed. Isolation of viable bacterial cells from surface-sterilized root segments of plants inoculated with an R:A ratio of 1:200 revealed that 80% of the bacterial population was made up of the Azospirillum strain. Under laboratory conditions transfer of the Rhizobium Sym(biosis) plasmid pBRIAN to strain SP245 was observed ex planta. However, the Sym plasmid was unstable in Azospirillum. A high frequency of Tn5 transfer from pBRIAN to strain SP245 occurred when strains ANU870 and SP245 were mixed in the rhizosphere and (or) in the root tissue. Tn5 transposed preferentially into the smallest indigenous plasmid of strain SP245 and was easily lost when this strain (SP245::Tn5) was not maintained on selective medium. This mutated Azospirillum strain caused plant growth stimulation when inoculated onto white clover plants.


2022 ◽  
Author(s):  
Vitaliy V. Chelnokov ◽  
Elena Zabolotnaya ◽  
Aleksey V. Matasov ◽  
Anna S. Makarova ◽  
Andrey N. Glushko

This research proposed the use of one of the most effective complexons – oxyethylidenediphosphonic acid, namely its derivative compound – phenyldiacetic acid,for the active sorption matrices of humus of mineral origin. The application of active components that stimulate plant growth and photosynthesis processes in hybrid preparations during reclamation were also proposed. Keywords: recultivation of landfill, plant growth stimulation, phytoremediation


1973 ◽  
Vol 52 (2) ◽  
pp. 162-165 ◽  
Author(s):  
D. J. Wort ◽  
J. G. Severson ◽  
David R. Peirson

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 219
Author(s):  
Gustavo Santoyo ◽  
Paulina Guzmán-Guzmán ◽  
Fannie Isela Parra-Cota ◽  
Sergio de los Santos-Villalobos ◽  
Ma. del Carmen Orozco-Mosqueda ◽  
...  

Plant-associated microorganisms play an important role in agricultural production. Although various studies have shown that single microorganisms can exert beneficial effects on plants, it is increasingly evident that when a microbial consortium—two or more interacting microorganisms—is involved, additive or synergistic results can be expected. This occurs, in part, due to the fact that multiple species can perform a variety of tasks in an ecosystem like the rhizosphere. Therefore, the beneficial mechanisms of plant growth stimulation (i.e., enhanced nutrient availability, phytohormone modulation, biocontrol, biotic and abiotic stress tolerance) exerted by different microbial players within the rhizosphere, such as plant-growth-promoting bacteria (PGPB) and fungi (such as Trichoderma and Mycorrhizae), are reviewed. In addition, their interaction and beneficial activity are highlighted when they act as part of a consortium, mainly as mixtures of different species of PGPB, PGPB–Mycorrhizae, and PGPB–Trichoderma, under normal and diverse stress conditions. Finally, we propose the expansion of the use of different microbial consortia, as well as an increase in research on different mixtures of microorganisms that facilitate the best and most consistent results in the field.


2021 ◽  
Vol 12 ◽  
Author(s):  
Maura Santos Reis de Andrade da Silva ◽  
Bianca de Melo Silveira dos Santos ◽  
Camilla Santos Reis de Andrade da Silva ◽  
Carolina Santos Reis de Andrade da Silva ◽  
Luiz Fernando de Sousa Antunes ◽  
...  

Plant growth-promoting bacteria (PGPB) and humic substances (HSs) are promising options for reducing the use of pesticides and mineral fertilizers. Although many studies have shown the effects of PGPB and HSs separately, little information is available on plant responses to the combined application of these biostimulants despite the great potential for the simultaneous action of these biological inputs. Thus, the objective of this review is to present an overview of scientific studies that addressed the application of PGPB and HSs to different crops. First, we discuss the effect of these biostimulants on biological nitrogen fixation, the various effects of the inoculation of beneficial bacteria combined with the application of HSs on promoting the growth of nonleguminous plants and how this combination can increase bacterial colonization of plant hosts. We also address the effect of PGPB and HSs on plant responses to abiotic stresses, in addition to discussing the role of HSs in protecting plants against pathogens. There is a lack of studies that address the role of PGPB + HSs in biocontrol. Understanding the factors involved in the promotion of plant growth through the application of PGPB and HSs can assist in the development of efficient biostimulants for agricultural management. This approach has the potential to accelerate the transition from conventional cultivation to sustainable agrosystems.


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