Use ofFrankiaand Actinorhizal Plants for Degraded Lands Reclamation

Abstract

Degraded lands are defined by soils that have lost primary productivity due to abiotic or biotic stresses. Among the abiotic stresses, drought, salinity, and heavy metals are the main threats in tropical areas. These stresses affect plant growth and reduce their productivity. Nitrogen-fixing plants such as actinorhizal species that are able to grow in poor and disturbed soils are widely planted for the reclamation of such degraded lands. It has been reported that association of soil microbes especially the nitrogen-fixing bacteriaFrankiawith these actinorhizal plants can mitigate the adverse effects of abiotic and biotic stresses. Inoculation of actinorhizal plants withFrankiasignificantly improves plant growth, biomass, shoot and root N content, and survival rate after transplanting in fields. However, the success of establishment of actinorhizal plantation in degraded sites depends upon the choice of effective strains ofFrankia. Studies related to the beneficial role ofFrankiaon the establishment of actinorhizal plants in degraded soils are scarce. In this review, we describe some examples of the use ofFrankiainoculation to improve actinorhizal plant performances in harsh conditions for reclamation of degraded lands.