Ecophysiological responses of different ploidy levels (Tetraploid and Hexaploid), of Cenchrus ciliaris to water deficiency conditions.
Cenchrus ciliaris L. is a perennial grass species that is widely present in Tunisian arid ecosystems. The ability to adapt to water deficiency of two provenances of C. ciliaris with different ploidy levels hexaploid (6x) and tetraploid (4x) was studied. Soil Water Content (SWC), predawn leaf water potential (Ψp) and midday leaf water potential (Ψm), number of leaves (NL), and shoot phytomass production were measured. Experiments were carried out under semi-controlled conditions of Sfax region (South of Tunisia). The factors studied were: ploidy level and irrigation treatments. Three irrigation treatments were applied: control T200 (200 mm year-1), T100 (100 mm year-1) and T50 (50 mm year-1). In our experimental conditions, our results showed that Cenchrus ciliaris species exposed to different irrigation treatments exhibited a decrease in all measured parameters. Different strategies seem to be developed by both provenances under drought conditions. Therefore, as soil water content decreased, tetraploid (4x) plants showed more negative leaf water potential (Ψp and Ψm) compared to hexaploid (6x) ones. More leaf number as well as shoot phytomass production by 6x provenances, in water deficiency conditions, suggests the ability of these provenances to support low water supply.