Assessment of intervarietal differences in drought tolerance in chickpea using both nodule and plant traits as indicators

5 lines of Tunisian varieties of chickpea (Cicer arietinum L.) inoculated with Mesorhizobium ciceri UPMCa7 were monitored during the vegetative stage on sterilized sandy soil. 2 levels of soil moisture were compared (100 and 33% of field capacity). The work was aimed at assessing the relative tolerance of these lines to drought and then, to research relationships between the level of sensitivity of plant growth and N content to drought and nodule, leaf and root traits. Drought limited plant growth of Amdoun and Neyer and decreased N content of Chetoui, Amdoun and Neyer. The latter N shortage was associated with increase in nodule mortality and restriction of nodule growth. In view of their minimal decrease in plant biomass and N content, Beja and Kesseb were the most tolerant varieties. Inter-varietal differences for water stress effects on nodule, root and leaf traits were limited to (i) change in root to shoot ratio (ii) loss of chlorophylls and (iii) nodule mortality. Each of these traits was considered as an indicator of stress tolerance. These indicators predict that the most tolerant variety was Beja based on higher increase in root to shoot ratio and Beja and Kesseb based on lower nodule mortality. When choice of the varieties should depend on the likelihood of water stress during the culture, Amdoun which presented the higher biomass per plant and the higher nitrogen content in control condition and ranked similarly to all other varieties in stress condition might represent a reasonable trade-off between high growth and stress tolerance when the probability of water stress to occur during the culture period is low.