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Pearl millet (Pennisetum glaucum (L.) R. Br.) is the most important summer cereal crop in the arid regions of Tunisia. A total of 283 accessions from 18 landraces were collected during the growing season of 1997 and evaluated in vivo at IRA, Benguerdane (during growing season 1998). Landrace (populations) grown by the farmers were shown to be mixtures of several types. Considerable variation was observed for all characters studied according to the descriptors developed by IBPGR and ICRISAT (1993). Time to flower varied from 30 to 66 days after sowing. Plant height ranged from 59 to 314 cm with a mean of 197.86 ± 0.43. Number of tillers varied between 0 and 19 per plant. Considerable variation in spike shapes was observed. Frequency distribution analysis of different spike shapes shows predominance of lanceolate (23.7%) followed by oblanceolate (23.5%) over cylindrical (18.3%), conical (15.7%), candle (8.7%), spindle (6.6%), club (3.1%) and globose (0.3%) types. The landraces collected mostly produced large, grey-coloured, obovate seeds, with partly corneous endosperm. Analysis of variance (ANOVA) was performed to evaluate variation amongst the different landraces. The differences are highly significant at (a = 0.05) for all characters studied. Duncan analysis and hierarchical clustering were carried out to (1) estimate resemblance between provenances; and (2) group landraces into homogeneous classes (clusters). The resulting dendrogram shows three principal clusters regrouping landraces according to their geographical origins or farming conditions. Pearl millet germplasm from Tunisia's arid region presents a wide range of genetic variability. It can be used as a starting basis for breeding programmes to select high yielding varieties tolerating adverse arid conditions.

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The process of soil salinization and the preponderance of saline water sources all over the world represent one of the most harmful abiotic stress to plant growth. This pointed to the importance of obtaining plants which are tolerant or resistant to salt, considering that projection of climate change for the coming years indicate an increase in temperature and rain scarcity. In the current study, the effect of NaCl was investigated on germinating seeds of Lathyrus sativus L., Vicia sativa L., Vigna radiata L. R.Wilczek and Vigna unguiculata L. Walp., by combining physiological, biochemical, biostatistical and ultrastructural analyses. Our results revealed that germination was not influenced by high NaCl concentrations, while seedling growth was affected even at low NaCl concentrations, probably due to an alteration in water uptake and in organic matter biosynthesis. Nevertheless, the synthesis of antioxidant enzymes, phenolic acids and flavonoids was registered in all species, which tended to cope with the increasing salt stress, allowing a response mechanism such as cytoplasm detoxification and cellular turgor maintenance. Besides, the ultrastructural analysis evidenced plasmolyzed cells close to cells with a normal ultrastructure with no appreciable differences among the species. This research deeply investigates the mechanism of salt‐stress response focusing on species never tested before for their possible tolerance to salinity.

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