Investigations regarding the influence of bacteria from rhizosphere zone of the plants on their growth and development and on some phytoparasite nematodes
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TODIRAŞ, Vasile, ONOFRAŞ, Leonid, MELNIC, Maria, ERHAN, Dumitru, RUSU, Ştefan, LUNGU, Angela. Investigations regarding the influence of bacteria from rhizosphere zone of the plants on their growth and development and on some phytoparasite nematodes. In: Sustainable use, protection of animal world and forest management in the context of climate change, 12-13 octombrie 2016, Chișinău. Chișinău: Institutul de Zoologie, 2016, Ediția 9, pp. 178-179. ISBN 978-9975-3022-7-2. DOI: https://doi.org/10.53937/9789975302272.88
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Sustainable use, protection of animal world and forest management in the context of climate change
Ediția 9, 2016
Conferința "Sustainable use, protection of animal world and forest management in the context of climate change"
Chișinău, Moldova, 12-13 octombrie 2016

Investigations regarding the influence of bacteria from rhizosphere zone of the plants on their growth and development and on some phytoparasite nematodes

DOI: https://doi.org/10.53937/9789975302272.88

Pag. 178-179

Todiraş Vasile1, Onofraş Leonid1, Melnic Maria2, Erhan Dumitru2, Rusu Ştefan2, Lungu Angela1
 
1 Institutul de Microbiologie şi Biotehnologie al AŞM,
2 Institutul de Zoologie al AŞM
 
Disponibil în IBN: 14 noiembrie 2018



Teza

The famous Russian scientist D. Docuceaev considered soil as a living organism of nature. He arrived at this formulation because the soil is overpopulated by different microorganisms, nematodes, viruses and other living organisms. Their spread into the soil is not uniform nor quantitatively (number), or qualitatively (at species level). Most of them, especially bacteria, micromycetes, actinomycetes are concentrated in the area of plant rhizosphere / rhizoplane. Here they find the necessary conditions to survive through the use of substances eliminated by plants in soil, which contribute in one way or another to the processes of seed germination, plant growth and development. Some of them have the capacity to produce biologically active substances, others - to lay phosphorus from organic and mineral compounds of the soil. Among the rhizosphere microorganisms there also are bacteria with the capacity to accumulate atmospheric nitrogen and to protect the plants from pests and various phytopathogen agents. Because of these capabilities the microorganisms can serve as an alternative in partialsolving the additional plant nutrition and respectively – increasing oftheir productivity. Because of mentioned characteristics bacteria from plantrhizosphere and rhizoplane became objects of investigation in order to use them for the benefit of plants. The studiesperformed within our team were focused on the study of the bacterial microflora of corn plantrhizosphere and rhizoplane. To this end rhizosphere soil samples have been collected from different districts of the republic, which served as sources for further isolation of microorganisms needed to complement the laboratory collection of microorganisms and their use in research process. During the investigations there were selected and highlighted new strains of bacteria potentially stimulating and protective for the plant. Thus, it has been determined that some metabolic products of the bacteria have the property to stimulate the process of germination and productivity in corn. The germination capacity of seeds under the influence of some bacteria of the genus Pseudomonas(P3Rf, P5Rf, P8Rf)andRhizobium RD2increased by 5.0 - 13.3% comparing to controland the productivity of the dry mass under the influence of a considerable number of bacteria grew on average by 9.1% - 20.9%. The highest degree of stimulation occurred in strains of Pseudomonas sp. PP2, P24Rp, PC5, Rh. japonicum RD2, the metabolites of which are thinneddilluted in proportion of 1/500-1/1000. The strains assessed as having a high degree of activity were then used as objects for laboratory investigation and vegetative experiences (innonsterile soil pots). After the analysis of data obtained it was determined that investigatedbacteria in soil conditions contributed to the increase of the gross mass of plants with 6.8%20.8%, and of the dry - with 14.6%- 21.8%. The best results were obtained when using strains Ps. sp. PC5, Rh. japonicum RD2 și P24Rpwith respectively 21.8%, 19.0% and 17.4% compared to the control. The remaining strains have increased the amount of dry matter from 14.6% to 15.9%. It has been found that some bacteria also positively influences the increase in root length, thus increasing relative to the control with 6.2%- 14.5%,being more pronounced in strains Rh. japonicum RD2– with 14,0% andPs. sp. P16Rpwith 14.5%. The other strains influence on the length of roots but with much weaker outcome measurements –of 6.2% - 9.6%. Some bacteria: Ps. sp. PP2, P16RP, Rh. japonicum RD2influencepositively upon the high of plant growth. The plants grewwith 7.0% -11.5% more high comparing to the control. In parallel with the above mentioned, investigations have been conducted on the influence of some bacteria in the rhizosphere of the corn plants(Rh. japonicum RD2, Pseudomonas sp. PC5, P3Rf) on the development of nematodes Ditylenchus destructor and D. dipsaci. The antagonist impact in vitro was studied using Rh. japonicum, Ps. sp. P3RF and PC5 and parasitic nematode species. Testing was carried out in laboratory conditions with a temperature of 25-270C at various time intervals - 1, 2, 4, 8, 21, 24, 48, 72 hours and 7....14 days. As control served nematodes maintained in distilled water. At the end of experience the effectiveness was verified. The results showed an increased efficiency of Rhizobium bacteria and of strain P3RF that had lethal action on nematodes Ditylenchus in proportion of 70%-75% at an interval of 24 hours, 95% - in 48 hours and 90%-97.5% in 72 hours. After a longer contact (7-14 days) was observed a destructive action on internal organs of parasitic nematodes - median intestine, gonad that lost their contours, were completely deformed, transforming into a homogeneous mass. An increased efficacy was shown by the strain Ps. sp. PC5, which caused 90% mortality in the parasitic nematode for 24 hours and 95-100% in 48-72 hours. Unlike Rhizobium japonicum bacteria PC5 at longer period of contact with nematodes (7-12 days) caused total destruction not only of internal organs but also of cuticle. Using the microscopictechnique we found the remnants of destroyednematodes. The conclusion made following a review of data obtained is that the investigated soil samples contained multiple strains of bacteria stimulating the processes of growth and development, as well as antagonistic action on parasitic nematodes of agricultural plants.