CHARACTERIZATION OF WATER DEFICIT TOLERANCE OF PONCIRUS TRIFOLIATA GENOTYPES RELATED TO DIVERSITY

Rootstock provides better adaptation to biotic and abiotic constraints. Poncirus and its hybrids are widely used since they are tolerant to Citrus tristeza virus. However, when grafted, most of them are considered to be sensitive to salinity and water deficit. Diversity does exist within the Poncirus trifoliate species, but little is known regarding the behaviour variability of genotypes to abiotic constraints. The citrus diversity of 72 P. trifoliate genotypes was investigated using SSR markers. Two major genetic groups were clearly identified. Five genotypes, belonging to each genetic group, were then selected to investigate their properties of tolerance to water deficit. Water deficit was applied by withdrawing irrigation for 4 weeks. Physiological parameters such as leaf stomatal conductance and gravitational water quantity were estimated. Among genotypes, we observed that some genotypes such as ‘Rubidoux’ were clearly more tolerant to water deficit than others such as ‘Pomeroy’. Interestingly, the genotypes that were sensitive belonged to one genetic group and the less tolerant ones belonged to the other group. Therefore, our results suggest that among the Poncirus genus, it is possible to select genotypes as parent in breeding programs, which are better tolerant to water deficit.