LOTUS SPP. NEW TECHNOLOGICAL AIMS IN MARGINAL SOILS

RUIZ, OSCAR A

OEIRAS

Conferencia; SEMINARIO INSTITUCIONAL; 2017

INSTITUTO NACIONAL DE INVESTIGACION AGRARIAS Y VETERINARIA

Inthe last decades there has been an increasing concern with heavy metals andmetalloids contamination, not only because of their toxicity to animals, plantsand microorganisms, but also because they become irreversibly immobilised insoil components. Arsenic is a ubiquitous trace metalloid and isfound in virtually all environmental media and its presence at elevated andtoxic concentrations in soils is due to both anthropogenic and natural inputs. Incontaminated soils, the number, biochemical activity and diversity ofmicroorganisms are reduced. Also, biodiversity of plants decreases drasticallyin the polluted soils. Leguminous and their associated rhizobial bacteria areimportant components of the biogeochemical cycles in agricultural and naturalecosystems and could aid the rehabilitation of disturbed areas. The knowledgethat some leguminous plants, mainly Lotusspp., are growing well in this type of soils, had attracted our attention forstudying these symbioses which are well adapted to harsh conditions. For this work we study rhizobial population isolatedfrom native leguminous plants of Lotusuliginosus Sch. growing in soils particularly affected by arsenic due therelease of liquid effluents from fertilizer and chemical industries. Theobjective of this research was to study rhizobial population in reference togenetic diversity, efficiency to fix nitrogen and levels of tolerance to As. Itwas also evaluated the effect of arsenic in the symbiosis. Thepresent work highlights the capacity of Lotusuliginosus to grow in contaminated soil strongly contaminated with arsenic.This specific legume is able to establish an efficient symbiosis with highlymetal-tolerant Bradyrhizobium strainswhich can promote vegetation cover, stabilizing metal-enriched soils, andtherefore it could be an attractive tool for phytostabilization.