Physiological and biochemical responses of three ecotypes of carob (Ceratonia Siliqua L.) against drought stress in Algeria

Abstract

The greatest failure rate of reforestation programs in Algeria is related to the water deficit especially at young plant stage. Hence, the objective of this paper is to study the responses to drought stress generated by three different water regimes 100% (control), 60% (moderate stress) and 40% (severe stress) of field capacity (FC) on 3 young populations of Ceratonia siliqua L. in Algeria with different eco-geographical origins (Zeralda, Tissemsilt and Ain Sefra). The germination seeds of these populations were conducted in February 2013. The results exhibit a significant decrease in stomata conductance (cs) and in relative water content (RWC) with the increase in the intensity of drought stress. Negative and significant correlations were recorded between the RWC and the intensity of drought stress in the studied plants compared to the control plants. A considerable increase of proline and soluble sugar was positively correlated with drought stress severity for the three ecotypes of Ceratonia siliqua L. Significant differences in the chlorophyll and carotenoid content were detected among the three ecotypes in three water regimes. According to the canonical discriminant analysis of our data, the three ecotypes were separated by the physiological and biochemical parameters studied. It is clear that the ability of drought tolerance in the three studied contrasting ecotypes is different. We suggest the following order with respect to the ability of drought tolerance: Ain Sefra - Tissmesilt - Zeralda.