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Tolerant citrus rootstocks are defined as Cl? excluders. However, little is known about the salt tolerance of cultivars used as scions, particularly the tolerance of monoembryonic citrus genotypes. To enhance the genetic resources for generating improved hybrid rootstocks, the evaluation of large samples of citrus species, including both monoembryonic and polyembryonic genotypes, is necessary. In this study, 12 citrus genotypes representing the major Citrus species and all the three genera of the Rutaceae family were subjected to moderate salt stress (75 mM) for 12 weeks to characterise their physiological response to salt stress. Various symptoms and physiological parameters were evaluated to characterise their salt sensitivity. These included plant growth (stem diameter), leaf chlorophyll content, leaf flavonoid content, maximum quantum yield of PSII [(Fm ? F0) / Fm)], net photosynthesis, stomatal conductance and leaf Na+ and Cl? contents. The results clearly demonstrated that the most salt sensitive genotypes accumulated high concentrations of Na+ and Cl? and maintained a fair growth and photosynthetic rate. By contrast, salt-tolerant genotypes accumulated less Na+ and Cl? and decreased their growth and gas exchange. Poncire commun citron and Marumi kumquat were the most sensitive species, while mandarins, pummelo and Australian sour orange were the most tolerant species. Among the genotypes, Engedi pummelo presented a specific trait for salt tolerance that has not been previously reported. Taken together, the results suggest that low leaf chloride content can be used as an indicator of salt stress tolerance in citrus genotypes. Exploitation of this indicator will enable the improved evaluation of citrus genetic resources and should lead to the identification of new sources of tolerance for rootstock breeding. (Résumé d'auteur

Growth and development of cereal crops are linked to weather, day length and growing degree-days (GDDs) which make them responsive to the specific environments in specific seasons. Global temperature is rising due to human activities such as burning of fossil fuels and clearance of woodlands for building construction. The rise in temperature disrupts crop growth and development. Disturbance mainly causes a shift in phenological development of crops and affects their economic yield. Scientists and farmers adapt to these phenological shifts, in part, by changing sowing time and cultivar shifts which may increase or decrease crop growth duration. Nonetheless, climate warming is a global phenomenon and cannot be avoided. In this scenario, food security can be ensured by improving cereal production through agronomic management, breeding of climate-adapted genotypes and increasing genetic biodiversity. In this review, climate warming, its impact and consequences are discussed with reference to their influences on phenological shifts. Furthermore, how different cereal crops adapt to climate warming by regulating their phenological development is elaborated. Based on the above mentioned discussion, different management strategies to cope with climate warming are suggested.

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