THE EFFECT OF HEAVY METALS ON NODULATION AND MICROBIAL ACTIVITY IN THE RHIZOSPHERE OF THE PEA

Heavy metals can either inhibit or stimulate microbiological processes in soil.
The subject of the study was the effect of different concentrations of Mo⁶⁺, Pb²⁺, Ni²⁺ and Cd²⁺ on nodulation and microbial activity in the rhizosphere of the pea.
Plants were grown in a greenhouse and treated with 10^-3, 10^-5 and 10^-7 mol kg^-1 soil of these metals fourteen days after emergence.
The first heck (K₁) treatment included soil without plants and heavy metals, whereas the second (K₂) consisted of pea rhizosphere soil that had not been treated with heavy metals.
Seven days later, microbiological analyses were done to determine the nodulation, the total number of bacteria, ammonifiers, azotobacter, as well as protease and dehydrogenase activity.

The total number of bacteria was larger in the trial variants treated with heavy metals than in K₁ but lower than in K₂. The various concentrations of heavy metals applied reduced dehydrogenase activity compared to K₂, but the activity was still high.

The number of ammonifiers decreased in all treatments with heavy metals compared to K₂ and increased with all concentrations of Ni²⁺ and Cd²⁺ compared to K₁.

The number of azotobacter in the rhizosphere was shown to have increased compared to K₁ and in variants with 10^-7 mol kg^-1 soil of Pb²⁺ compared to K₂. Application of heavy metals decreased root nodulation.

I Balkan Symposium On Vegetables and Potatoes

M. Jarak, M. Govedarica, . , M. Ubavic, N. Miloševic

Cd²⁺, Mo⁶⁺, Ni²⁺, Pb²⁺, micro-organisms

https://doi.org/10.17660/ActaHortic.1997.462.32