Assessment of Drought Stress Tolerance of Mangifera indica L. Autotetraploids

Mango can be grown in subtropical and semi-arid regions, where using commercial cultivars and rootstocks with improved resistance to drought is crucial. Induction of polyploidy has been widely applied in breeding programs for increasing crop drought resistance. In this study, drought resistance of several mango cultivars and their respective autotetraploids was evaluated. Leaf morphology and physiology were monitored in two-year-old plants during a period of water withholding and subsequent rewatering. Even though all tetraploid cultivars presented morphological differences in leaf traits, the effect of ploidy in delaying leaf water loss and its detrimental effects of photosynthesis was only observed in 'Gomera-1'. As a result of this, this cultivar sustained maximum levels of quantum efficiency and gas exchange for a longer period than the rest of cultivars. Therefore, the isohydric strategy of this tetraploid was not associated with earlier stomatal closure. Proline did not increase in the isohydric cultivar probably due to the maintenance of high leaf relative water content. In contrast, in some anisohydric mangos, proline increased when leaf water content decreased below 80%. Some diploids exhibited higher levels of proline than tetraploids, but recovery of plant functionality after rewatering did not differ from the rest of cultivars. We conclude that drought resistance in mango can be improved by using polyploids with water-saving physiological traits.