Résumé
The purpose of this investigation was to assess the nodulation and the plant growth of white lupin (Lupinus albus L.) in Tunisian soils. For this, two L. albus varieties, Mekna (Tunisian) and Lumen (French), were cultivated in soils sampled from 56 locations without a history of lupin cultivation or rhizobial inoculation. All soils were analyzed for their physical and chemical proprieties. At harvest, nodulation and plant growth parameters were recorded for both varieties. The results showed that 75% of soils were alkaline and calcareous. Nodulation was often poor, suggesting the absence of host-specific rhizobia. It was absent in 41 soils, abundant in 2 (Sejnen and Mraissa), and scarce but efficient in the remaining 13 soils. Furthermore, white lupin varieties have different responses to native nodulating bacteria since the local variety, Mekna, developed significantly more root nodules and in more soils than the imported variety. Growth parameters and nitrogen accumulation were also measured as indicators of nitrogen fixation efficiency. Considerable variability was detected among soils. It was found that the imported variety, Lumen, showed high sensitivity to the soil active lime content compared to Mekna. Interestingly, high biomass production and nitrogen accumulation were recorded in soils originating from Madian, Tejerouin, Benouria, and Oued zinga, with a high active lime content ranging from 26% to 31%. This finding suggested that white lupin can be cultivated in Tunisian calcareous soils, especially the most promising local variety, Mekna. Isolation and the selection of efficient bacteria from alkaline calcareous soils are necessary to promote the development of this valuable legume in Tunisia.